I haven’t had time to delve into this, but there seems to be a general interest in emissivity through several lines of investigation on the talkshop recently. Physics makes definitions of things in ideal conditions. Emissivity is defined as the radiation a body will emit at a specific temperature. This quantity is crucial to our understanding of the way Earth balances its energy budget of incoming solar energy with emission from various parts of the system. However, emissivity at different wavelengths forms a curve, it isn’t the same at all wavelengths for a specific material. Moreover, in a non-vacuum, radiation isn’t the only means by which energy can leave a body. Conduction, latent heat of vaporisation (evaporation) and convection also play a role, and dominate over radiation in the Earth’s troposphere.
The most important material to consider so far as Earthj’s energy balance is concerned is seawater, since it covers 70% of the planet.
Contributor ‘Max’ turned up some interesting plots for the emissivity of seawater (and land) the other day, which seem to contradict each other. Here are two of them:
MODIS satellite image showing emissivity of around 0.7 at 0.83um for the ocean
ICESS seawater emissivity curve showing 0.983 emissivity at 8.3um
Why the difference?
Wayne Jackson recently posted an alternative energy budget which finds that the ‘effective’ or ‘operational’ emissivity of the surface is around 0.67.
This seems to show that we need to subtract the energy involved in the latent heat and conduction from the figure given by the (in)famous Trenberth and Keihl energy budget diagram for the long wave radiation going up from the surface. But it is claimed that their figure of 356W/m^2 is measured by radiometers. Many people dispute the accuracy and calibration of these devices, but assuming it is a true average of measurements, how can we reconcile the difference?
Could it be that the long wave radiation being exchanged in the air is simply a transient expression of the energy being moved by convection and latent heat? This would make the long wave energy flux within the troposphere more a ‘symptom’ of its energy content than a cause of its temperature or the lapse rate, since it is constantly cancelling out at each altitude level, apart from the relatively small component of the upward radiation which escapes to space through the ‘atmospheric window’.
Several people commenting on their own and each others investigations in this area have been spread across several threads recently. I’m posting this one to get them all together in one place to discuss these issues. I suggest we make a conscious effort not to get sidetracked by anyone, mentioning no names Tim Folkerts, who tries to obfuscate the issue with energy budget calculations which assume a perfect emissivity of 1 or an arbitrary figure such as 0.9 for any part of the system.
Have at it! 🙂
Tallbloke's Talkshop 
“This is not possible. Both surfaces at the same temperature (and of course assuming they have the same emissivity) will emit the same value of radiation.” ~scienceofdoom
Hmmm, so if I’m understanding you correctly, you’re saying emissions determine temperature?
Max,
Temperature determines emission of thermal radiation.
This is one component of energy out.
Sum of energy out – energy in = Change in internal energy.
If this is positive, temperature increases (or phase change like ice melts).
If this is negative, temperature decreases (or phase change like ice freezes).
You can see a few very simple worked examples of heat transfer calculations in Heat Transfer Basics – Part Zero.
TKF, last time I looked the energy was not that different.
This is an area tending to be outside of human senses, therefore does not exist except it does.
At ground level falling ice is not particularly common, happens everywhere though. Some interesting papers, looks like Google have well screwed me, have to do your own search. (about tracking, will do anything to try and get this but I block them, don’t like it, academic search is plain useless)
My point as much as anything is multiple phase transitions occur. Whole thing is so complex nothing is going to be decided.
David Socrates says: January 7, 2013 at 10:51 am
“Well suricat/Ray, I don’t. Perhaps you would care to enlighten me, and possibly the rest of us, on what you think those implications are? 🙂 ”
Sorry for the delay, but I think I may have a mild version of this ‘Noro-virus’ thingy. This thread’s moved on some though. 🙂
I think tchannon gave the closest hint! How can you base an energy transport rating on ‘precipitation’??? Basically, you can’t! At least, not if you ignore the evaporation of the precipitation before it strikes ‘ground zero’.
Whatever figure you come up with, calculated by surface ‘rainfall amount’, the energy transport is appreciably higher. Heck, some clouds dump rain that never gets to reach the ground (there’s a Meteorological name for this type of rain, but I can’t think of it just now 🙂 ).
If you think about it, ‘precipitation’ is the reason why ‘RH’ (Relative Humidity) is higher at low altitudes than higher up. It gets ‘rained into’! It’s also an energy source for atmospheric ‘turbulence’ that converts PE to KE Stephen. 🙂
When you add on the ‘energy transport’ ‘throughout’ the depth of the atmospheric ‘exchanger/heat pump’, you’ll find that more ‘transport’ is taking place via the atmospheric hydrological cycle than that shown by ‘ground precipitation’ alone.
Best regards, Ray.
Yes, I’ve read most of the posts on your site, lots of informative stuff over there, I’ve also been reading books on [insert subject here] for the last… 25 years or so.
I simply asked because on the one hand you correctly stated that temperature determines emissions, while you have also essentially stated that a surface at a given temperature must emit a given level of radiation.
If the ground is at 289 K it possess a certain average amount of kinetic energy.
If the ground has convection and evaporation taking place, those processes reduce the kinetic energy of the ground, and transfer that kinetic energy to the atmosphere, raising the temperature there.
If the atmosphere is at a non-zero temperature lower than that of the ground, then it possesses a certain average amount of kinetic energy as well, and that reduces the overall transfer from the ground upwards to the atmosphere.
Sometimes particles with a certain amount of kinetic energy emit photons which carry a bit of that kinetic energy away, as expected because photons have momentum.
A surface at 289 K can transfer up to a given amount of kinetic energy to another body.
You didn’t seem to have a problem with this part of my earlier post:
“As soon as the thermal emissivity is known air may be allowed into the vacuum chamber so that convection also contributes to the heat loss of the rod. Convection may be described by Newton’s law of cooling, stating that the net loss of heat per unit surface is proportional to the difference between the temperature of the surface of the cooling body T₁ and the temperature of the surrounding convective medium T₂ : “ ~From: http://www.nat.vu.nl/environmentalphysics/REAL%20Experiments/Heat%20radiation/Radiation.html
…
You also didn’t say anything about this part: “Under steady state conditions, the net radiation emitted per unit surface by the enclosed body is proportional to the emissivity e, the Stefan – Boltzmann constant s and depends on the temperature of the body T₁ and the enclosure T₂ respectively”, though the bolded part IS rather important here.
You accused me of “inventing a magic world” where radiation and convection and evaporation all contribute to the net transfer of heat from the surface to the atmosphere.
Why is that? Is it because I suggested a surface at 289 K won’t transfer more energy as heat than it could radiate if it was a black body? Is that really such a controversial suggestion?
That was supposed to start out with a quote from scienceofdoom, I changed a part of it and forgot to put the quote back in: “You can see a few very simple worked examples of heat transfer calculations in Heat Transfer Basics – Part Zero.” ~scienceofdoom
tchannon says :”TKF, last time I looked the energy was not that different.”
Are you referring to latent heat of vaporization (2260 J/g) vs fusion (334 J/g)? That is a factor of 7 different.
Max,
There’s a formula for each type of heat transfer.
Regardless of the theorizing you can come up with in your head, the formula describes the real thermodynamics.
If you wrote down your words as a formula it would be easier to compare with what is in textbooks.
Intuition is a much worse guide than a textbook and, if it conflicts, work on the basis that your intuition is wrong.
Thermal emission of radiation from a surface in W/m2 = emissivity x 5.67×10-8 x T4, where T is in Kelvin.
[mod: from followup: ..last comment I tried to do superscripts but the tags didn’t work. In case it’s not clear – W/m^2, 5.67×10^-8 and T^4]
I misremembered, sorry
http://www.engineeringtoolbox.com/melting-boiling-temperatures-d_390.html
Total Power=Radiated Power+Convected Power=εσA(T₁⁴−T₂⁴)+hA(T₁−T₂)
Same equation as the image link in this quote:
“The total power of the heat removed from a hot object at T₁, enclosed by a black body under normal atmospheric conditions is given by the sum of the total amounts of heat removed per unit time through both radiation and convection as given in eq. (2.7) and (2.9):
Note that the heat loss due to radiation is driven by the temperature difference between the hot object and the black body and the heat loss due to convection is driven by the temperature difference between the hot object and the air.”
If we assume the heat loss from surface radiation is driven by the difference between the surface temperature and the cosmic microwave background then yes it would make sense to assume the power is 396 W/m^2.
The moon lacks an atmosphere worth considering here (technically it’s not non-existent, but it sure ain’t much) and it makes sense to assume it radiates at full power for a given temperature and emissivity into the vacuum(ish) space around it.
The earth is not radiating into a vacuum directly from the surface, the surface radiates into an atmosphere which is much closer to the surface temperature than the CMBR is.
If a surface in a vacuum at 289 K radiates 396 W/m^2 while a surface at 289 K with an atmosphere loses 97 W/m^2 from convection/evaporation AND 396 W/m^2 from radiation… couldn’t you warm a surface up in a vacuum, then place it in an atmosphere and get back the radiated power plus the energy lost through convection/evaporation?
Even if the efficiency wasn’t perfect on the convective/evaporative heat collection, you’d still be able to use 396 W/m^2 to heat a surface to 289 K in a vacuum then expose it to moisture/air and get back 396 W/m^2+97 W/m^2 potentially!
Yeah, it’s not super easy to get a vacuum, but how hard would it be to slide a metal plate out into the sun on a spaceship, then pull it back inside the ship and collect what it radiates+evaporates+convects?
We’ve clearly been going about things all wrong with our silly solar panel and radiothermal power generation systems, all we need is a meter of metal coated in carbon nanotubes (one of the blackest substances known) an airlock and way to slide it back and forth!
“Hang on, gotta go wind up my spaceship again!”
Max, careful, that equation looks proper but yet seems incomplete. It needs one more term for the mass evaporated per second from the surface also. On Earth, at the 80 W/m2 that TFK stated, it would be about 0.0354 g/s of H2O averaged Earth-wide. All of these three modes of energy transfer, radiation, conduction and evaporation of surface cooling are all, at the deepest level in physics, are either electron-photon or electron-electron interactions so you need to ask yourself this: If a given amount of energy is present in the top few molecules of a surface, can they all three fully express themselves simultaneously as if the other two did not exist or will these three modes share in the loose of that energy per second. Can these vibrating phonons do triple-time or have we just created energy transfer from nothing for the other two modes. I say share and I wish Richard was still alive so we could ask an authority on qed and we wouldn’t have to argue so much over this topic. What would that mean if the surfaces in question were wet and evaporating? The emissivity would go down accordingly.
Ask yourself: How is the emissivity of water determined, with RH of 0% or RH of 100% so no loss by evaporation could also occur simultaneously and sapping some of the thermal energy present in the surface molecules as the test is being performed.
Those seem to be the questions we should ask ourselves. Maybe someone can find a reference to that very topic but it’s a bit deep for the web.
Again, maybe that too is a bit too complex a thought to raise here but I just had to get it out into other minds to ponder on a bit.
Well, I wasn’t trying to work out the equation with evaporation included, just radiation+convection.
I would also like to see what Feynman would have to say on the matter, and you’re spot on about the electron-electron or electron-photon interactions.
If the surface is radiating 396 W/m^2, where does the energy for convection/evaporation come from?
S.o.D says:
Intuition is a much worse guide than a textbook and, if it conflicts, work on the basis that your intuition is wrong
I can almost hear the learned geology prof leaning back in his chair, steepling his fingers together and saying that to the discoverer of plate tectonics circa 1958… 🙂
But I think all we’re really disputing here is whether it is more useful to consider the net LW flux or the upward and downward components of it.
The net flux warms the air as it cools the ocean. The important difference between the two processes is that in the lower troposphere the upward component warms the air by transferring energy to GHG’s, whereas the downward component predominantly cools the ocean by driving evaporation, since it is all absorbed within a few micrometers of the surface, and concentrates its energy there.
That is where the radiative model fails; by thinking water behaves the same as air. It doesn’t.
Wait, how does DWIR drive evaporation?
suricat says:
“Whatever figure you come up with, calculated by surface ‘rainfall amount’, the energy transport is appreciably higher. Heck, some clouds dump rain that never gets to reach the ground (there’s a Meteorological name for this type of rain, but I can’t think of it just now ).”
That’s a good point and illustrates how ‘dodgy’ some of the KT2009 figures are.
Once airborne the energy stored in evaporated water can be transported horizontally as well as vertically.
Hydropower stations intercept some of this energy.
Has the total world hydropower potential been factored in?
Equator to pole energy transfer equalises surface temperatures beyond what a crude radiative model would indicate.
Rain which doesn’t reach the ground is called virga.
suricat says:
>> Whatever figure you come up with, calculated by surface ‘rainfall amount’, the energy transport is appreciably higher. Heck, some clouds dump rain that never gets to reach the ground (there’s a Meteorological name for this type of rain, but I can’t think of it just now ).”
Bryan says:
>That’s a good point and illustrates how ‘dodgy’ some of the KT2009 figures are.
No, that is not particularly a good point. Yes, such things definitely exist. But that only transports energy WITHIN the atmosphere. Since “within the atmosphere” is not to the ground nor to space, there is no place for it in the KT diagram.
Similarly, the KT diagram summarizes global averages, so transport from equator to poles is also not included. Yes, climate models include such things; no, this very basic summary does not.
tjfolkerts
The IPCC Greenhouse Theory tries to explain why the near Earth surface temperature is not 255K.
The KT 2009 diagram is part of the explanation.
It accounts for the 40inches of rainfall.
Suricat points out that there is a secondary evaporation/condensation cycle taking place.
This must effect the temperature of the atmosphere making it warmer than it would otherwise be.
This in turn has an effect on the radiative values and other processes such as convection.
Perhaps this is why sceptics have little regard for diagrams like KT 2009 .
Bryan claims:
“Suricat points out that there is a secondary evaporation/condensation cycle taking place.
This must effect the temperature of the atmosphere making it warmer than it would otherwise be.”
Why must it make the atmosphere warmer???
This cycle merely moves energy around WITHIN the atmosphere. You can’t “rob Peter to pay Paul” and expect to come out ahead.
Yes, evaporation — and convection and conduction and radiation — all move energy around WITHIN the atmosphere. Yes, all of these affect the others. All of these would impact the lapse rate WITHIN the atmosphere. None of these are shown WITHIN the atmosphere on the KT diagram — they are beyond the scope of that simple summary. The KT diagram summarize the energy flows BETWEEN the regions, not WITHIN the regions.
Wayne,
Looking forward to your response to my comment of January 7, 2013 at 8:07 pm and at at 9:37 pm.
Everyone Else,
So far the “glaring flaws” in KT1997 have not been explained.
1. Max has some issues but they turn out to be with heat transfer basics.
2. Wayne has some issues but has not clarified what they are. They appear to be with the DLR value, measured with a pyrgeometer. This same principle is used to measure the OLR by satellite. And to measure the solar radiation at TOA and the surface. Which readings can be trusted has not been explained.
Clarification is pending, I hope.
3. Tallbloke is unsure, despite ‘glaring flaws’ being his earlier words.
4. Bryan has now come to the party with:
Bryan explains he is unhappy with KT2009 because the values are wrong, but he neglects to tell us what the correct values are.
Perhaps everyone on this blog is now content that the values provided, along with their respective uncertainty, in KT1997 (and perhaps the TFK2009 update) are good approximations to the global annual average?
[Reply] You are editorialising innacurately. Stick to discussing the science, including the incorrect ‘window’ figure.
Sorry guys, but I take exception to all this blather about Trenberth’s figures not being correct. The conversation now seems to be wandering all over the place and the arguments are getting qualitative and confused. Let’s keep the focus on exactly where the Trenberth figures are wrong, and why, and by how much.
As I have been saying repeatedly on this blog trail and on the Tim Folkerts one, having read the K&T 2009 paper recently I was impressed that Trenberth et. al. appear to have done the best job possible with the limited data then available.
It seems that the in-flow and outflow radiant power density figures, from and to space, were based on reasonably strong empirical evidence. But the surface-atmosphere energy flows were more speculative, relying more on theory than observation. Since then, new experimental evidence suggests that the ‘atmospheric window’ value should be raised from Trenberth’s 40Wm-2 to around 63Wm-2. This adjustment is now reportedly supported by Trenberth et. al.
If this correction is made, it necessitates a compensating reduction in the surface-to-atmosphere upwelling radiation from 356Wm-2 to 330Wm-2, which surprise, surprise, almost exactly balances Trenberth’s “back” radiation figure of 333Wm-2 from atmosphere-to-surface.
Of course we all understand that these figures are subject to significant uncertainties either way and that it would be rash to assume that up and down radiation exactly balance. But heck, even if they don’t exactly balance, it is surely looking more and more likely that there will be very little remaining residual radiation, either up or down.
Within this discussion, we here probably have several different agendas:
TB wants the residual to be
downwardsupwardswarm his oceanto cool his ocean by enhanced evaporation.[Mod note] See further comments below.
Tim and SoD want the residual to be upwards so they can avoid having to respond to endless “Kirchoff’s Law” radiative balancing assertions. 🙂
And I really want the residual to be zero because…er… it’s an effing residual.
I am tired of hearing about a very small (and possibly non-existent) effect when there is a huge unacknowledged elephant in the room: the COLOSSAL FUND of Kinetic Energy in the atmosphere, maintained at its FIXED level by a continual FIXED rate of inflow of 175Wm-2 of Kinetic Energy, derived from radiation arriving from the Sun.
And yes, because the earth’s surface is at a temperature of around 288K at the surface and contains GHG molecules, there is consequently a lot of radiation everywhere in the bulk of the atmosphere, just as is always associated with bodies that are at a temperature above absolute zero. But we shouldn’t be beguiled into thinking that radiation is some kind of magic dust that is by its very existence able to affect the KE balance of the atmosphere. In the bulk of the atmosphere, for every emission of a photon (and consequent loss of a unit of KE), there is an almost immediate absorption of that photon (and consequent re-gain of that same unit of KE). So in the aggregate, the swirling fog of photons does what photons always do…it swirls around in all and every direction doing…absolutely nothing.
However that’s in the bulk of the atmosphere. At the interfaces with space, photons do have vital roles to play:
(1) The transport of energy through the vacuum over large distances (Sun-to-earth; atmosphere-to-space).
(2) The transformation of energy (radiant-to-KE on input; KE-to-radiant on output) via GHG molecules.
But what photons cannot do, once they are swirling around inside the atmosphere, is influence the quantity of KE contained in it…because they are just swirling around…in and out of existence, much too busy conserving their own FIXED FUND of radiative energy.
This then moves the focus of the debate towards what I think is the key remaining open question:
What establishes the balance between the incoming fixed flow of energy and the consequent fixed level at which the FIXED FUND OF KE in the atmosphere is steadfastly maintained?
As with all such stable balancing acts in physics, it requires an inherent non-linearity, some form of resistance to input flow that gets less resistant as the input flow gets faster, and gets more resistant as the flow gets slower, thus maintaining the stable FIXED FUND of Kinetic Energy in the face of small perturbations. In other words, the classic stabilising negative feedback loop.
Well I think there are two candidates for this stabilisation process:
CANDIDATE A: THROUGHPUT THROTTLING: The retention of KE in the atmosphere is controlled by the very slow mechanical method of transporting KE. It involves the physical transport of air travelling several kilometres up the atmospheric column. On average, it takes a long time for a parcel of KE-energised air near the bottom of the atmosphere to travel up to a high enough point where its KE can be transformed to radiation by GHGs and lost to space. During that journey, the KE contained in that parcel of air is a contributor to the atmospheric KE FUND. So slower convection means a LARGER FUND OF KE. And faster convection means a SMALLER FUND OF KE. The convection adjusts itself by simple physics to the fixed incoming rate of energy flow. This is a classic negative feedback loop mechanism, keeping the FUND OF KE in the atmosphere at a fixed level and therefore at a fixed temperature.
CANDIDATE B: OUTPUT THROTTLING: The rate is controlled by the GHGs at the ToA that convert KE to radiation that is lost to space. Their ability to do so is related to the temperature of the air in the upper atmosphere. This is because (for any given fixed concentration of atmospheric GHGs), as we climb higher and higher, even though the GHG molecules are more and more likely to emit photons, the air up there gets cooler and cooler. So the radiation that the photons emit is of a lower and lower intensity. The balance between these two effects means that the rate at which KE can be converted to radiant energy that escapes to space is proportional to the temperature of the atmosphere. If the atmosphere gets a bit warmer up there, it is easier for the GHGs to emit more radiation, thus reducing the FUND OF KE more rapidly and therefore reducing the temperature back down. And vice-versa. This is a classic negative feedback loop mechanism, keeping the FUND OF KE in the atmosphere at a fixed level and therefore at a fixed temperature.
The similarity between A and B is that they both involve negative feedback mechanisms that tend to return the system to a balance point (a fixed level of KE FUND) in the face of small perturbations: the classic test of a stable physical system.
The difference between A and B is that A is highly insensitive to changes in the concentration of GHGs in the atmosphere; whereas B is highly sensitive to such changes.
As I have said to Tim on the other thread, qualitative arm waving will not help anyone to decide between A and B. What is needed now is a crisp, clear, focussed and meaningful quantitative discussion, probably at the level of statistical thermodynamics, to help resolve this issue one way or the other.
Is that debate now happening? The heck it is.
By coincidence, in today’s Times Tom Whipple, Science Correspondent, reports on the UK Met Office prediction that there will be no further warming of the planet’s surface over the next five years. He says: “the downgrading of its predictions for the effects of climate change mean that by 2017 it is projected that there will have been no global increase in temperature for almost 20 years”.
He then goes on to quote Professor Julia Slingo, “the Met Office Chief Scientist” as saying: “When you look at global warming, you should never look at anything less than a decade at a time. One of the key determinants is what the oceans are doing; there are natural decadal variations in slow currents. These forecasts are as much about changes in that as [in] global warming.”
I never thought I would ever agree with anything a spokesman for the Met Office ever said. But for once I think this lady has got it asolutely right.
Ah…except that I would use 160 years as my smoothing interval, the full length of the global instrumental temperature record.
Doing just that, and using HadCRUT3 (the Met Office’s own data) shows that the earth’s mean surface temperature has risen at a long term rate of just 0.4degC per century, with a shorter term superimposed ~67 year up-and-down oscillation, almost certainly due to ocean heating/cooling, of plus or minus 0.25degC, as depicted in the following two charts:
http://www.thetruthaboutclimatechange.org/tempsworld.html [HadCRUT3]
http://www.thetruthaboutclimatechange.org/amo.html [HadCRUT3 detrended]
During its 30 year sharp upturn phase from 1975 to 2005, the natural ~67 year ocean-heat-related oscillation served climate alarmism well. Superimposed on the long term trend, it looked like an alarming change in just a third of a century – especially exciting for those not schooled in either statistics or physics who concentrated their eyes on the extreme peaks and troughs in the raw year-on-year data (see the grey underlying plots).
So the arrival of the crest of that natural ocean-related temperature ocillation has now induced increasing panic, particularly among those whose careers are wedded to the ‘dangerous global warming’ mantra. Hence the increasing rate of climate-babble from learned Professors and their numerous and vocal fellow travellers.
David says:
“TB wants the residual to be downwards to warm his ocean.”
What?! I’ve been saying for four years or more that downwelling LWIR cannot warm the ocean. Since it is all absorbed within the top few microns of the surface water, all it can do is help promote evaporation, which COOLS the ocean.
Furthermore, I pointed out above in response to your previous comment that the new ‘window’ figure more or less exactly matches the upwelling net flux from the ocean surface. I doubt that is a coincidence, and probably relates to the intimate link between ocean surface temperature, atmospheric pressure, and cloud albedo.
Why not both A and B ?
The proportion of each depending on the type of forcing element ?
A relates to the vigour of convection and the speed of the water cycle.
B relates to the improved radiative capability of an expanded and so less dense atmosphere.
However, the more effective B is the less has to be done by A in order for balance to be maintained and vice versa.
But in the end it all comes to zero whichever response is the more efficient in any given situation.
For example.
i) When the oceans release more energy to the air during an El Nino then initially convection (A) would increase because there would be more evaporation and water vapour is lighter than air but the extra vigour in the convective process raises atmospheric height which speeds up B as well because water vapour is a GHG that can radiate upward.
ii) When the sun alters ozone quantities in the stratosphere then initially outward radiation from that ozone increases and less energy reaches the surface ecause ozone responds to solar energy rather than IR from the surface. So in that case B increases first but because less reaches the ground A would actually slow down.
iii) With non condensing CO2 in the troposphere it would be more of a mix of the two processes because such CO2 can both radiate out and influence the speed of the water cycle and hence convection.
So the system can switch as necesary between A and B depending on which negative feedback is the more efficient.
That is actually implicit in my concept of a diabatic loop (candidate B ) and an adiabatic loop (candidate A)
And I agree with this:
“But what photons cannot do, once they are swirling around inside the atmosphere, is influence the quantity of KE contained in it…because they are just swirling around…in and out of existence, much too busy conserving their own FIXED FUND of radiative energy.”
With the minor proviso that the fixed fund is actually KE plus PE and expansion or contraction of an atmosphere can arrange thermal stability by switching between the two as necessary with candidates A and B then following on in the most efficient combination.
“David says:
“TB wants the residual to be downwards to warm his ocean.””
Yes, TB, I spotted that mistake too.
Funny how much scope there is for slips like that even amongst those of us who agree on the basics 🙂
Roger: Apologies. My mistake. Careless writing! Please do feel free to replace “warm his ocean” by “cool his ocean by enhanced evaporation”. Those comments about our different perspectives was only intended to be light hearted. My main point is that we should not get hung up on a comparatively residual figure.
Re. the new ‘atmospheric window’ value of 63Wm-2 being comparable to the upwelling net flux from the oceans, I agree this is unlikely to be a coincidence. For all I know it may be the discovery of that empirically determined figure for upwelling net flux from the oceans that had a major part in suggesting the proposed change to Trenberth’s original 40Wm-2 value.
[snip]
So my summary of “3. Tallbloke is unsure, despite ‘glaring flaws’ being his earlier words.” seems to be spot on. ‘Stick to discussing the science’ is what I am doing.
[snip]
[Reply] Nothing in that diatribe about the 20W/m^2 glaring flaw in the ‘window’ figure though. Nor the glaring 40W/m^2 error in cloud absorption as EMPIRICALLY determined by the USAF.
We’re having an interesting discussion here, and I won’t allow you to derail it with inaccurate summaries of peoples positions. Just state your own, and leave others to state theirs.
Stephen,
Why not both A and B ?
As I wrote my piece I thought that there was no logical reason why both mechanisms shouldn’t be in operation. Then I thought that would just be a great get-out clause because it would let people off the hook from bothering to examine each mechanism in turn, quantifying the effect in detail.
The important thing is that those who believe that Candidate A works should attempt to persuade others by reasoned scientific argument. Likewise those who believe Candidate B works should do the same. Rather than us all just having endless back and forth “arguments by assertion”.
In any case, even if both mechanisms do turn out to operate, we need to know whether and why they exactly complement one another, as you suggest they do. I think it is likely that this will only be achievable if we can place better quantitive limits on the strength of each effect. So we need to do that detailed quantitative work anyway in both cases.
And finally…in logic, there are of course four outcomes to such a discussion, not three, the fourth being that neither mechanism is correct. 🙂
Hmmm, scienceofdoom, you say I have issues with “heat transfer basics” because I don’t think it is plausible for molecules at a given temperature to have enough kinetic energy available for full power black body radiation and convection and evaporation?
If the surface is losing 396 W/m^2+80 W/m^2+17 W/m^2 averaged over a given period of time then there is no possible way the average temperature over that period of time is 289 K.
I’d love for you to find me some sort of source which says that bodies emit full power radiation as black bodies while also undergoing convective and evaporative energy transfers.
_________
David, this comment is spot on: https://tallbloke.wordpress.com/2012/12/14/emissivity-puzzle-energy-exchange-in-non-vacuums/#comment-40312, I’ve never liked the idea that a system which exhibits stability over gigayears is packed with high gain positive feedbacks.
David wrote “Doing just that, and using HadCRUT3 (the Met Office’s own data) shows that the earth’s mean surface temperature has risen at a long term rate of just 0.4degC per century, with a shorter term superimposed ~67 year up-and-down oscillation, almost certainly due to ocean heating/cooling, of plus or minus 0.25degC”
Absolutely right. Even if you assume an underlying logarithmic increase in warming directly caused due by CO2 increases, any short term increases are still dominated by the ~65 year oscillation evident in the data. Such a fit is described here. Extrapolating forward with ever increasing CO2 levels till 2100 (B1 scenario) we can make the following predictions:
2000 – 2030 : essentially no change in temperatures
2030 – 2060 : a further ~ 0.5 deg. rise similar to 1950 – 2000
2060 – 2100 : no further increase.
Nicolas Scaffetti explains the 60 year oscillation as a tidal effect in the orbit of Jupiter on the Sun . I am not convinced and agree with you that it is more likely to be the AMD and PDO oscillations in the Oceans.
Either we can look forward to a great deal of squirming and large amounts of egg being wiped of faces of leading politicians, their “scientific advisors”, and anti-growth carbon extremists. That is if we still have any economic activity left functioning by 2030 !
I would not be so quick to dismiss influences like Scaffetti proposes.
The solar system consists of Sol, Jupiter, and some debris. There are periods when the barycenter is a point above the surface of our star, and that is due mostly to the effects of Jupiter, so there is VERY significant torquing and mixing taking place due to those tidal effects.
I do not see how that could take place and have no noticeable effect on the behavior of the sun.
Though I have to point out that a 60 year period is due to Jupiter AND Saturn, Jupiter alone orbits several times in that period, but the orbital resonance with Saturn is roughly 60 years as I recall.
David Socrates said:
“In any case, even if both mechanisms (candidate A and candidate B) do turn out to operate, we need to know whether and why they exactly complement one another, as you suggest they do. I think it is likely that this will only be achievable if we can place better quantitive limits on the strength of each effect. So we need to do that detailed quantitative work anyway in both cases”
It will be an awfully long time before that data is available.
In the meantime we can just look at real world trends and timings which to me show that both processes are everywhere, all the time and firmly negative to any forcing element.
As to why they exactly complement one another we need only look at the settled science relating to gas clouds in space, sun formation and planetary gas giants.
That science says that the only relevant factors for the internal temperture of a gas cloud with or without a lump of rock inside are the mass of the gas, the strength of the gravitational field and the amount of energy available.
Given that, mere changes in radiative characteristics must always be countered by changes in energy throughput.
Stephen,
Just a couple of points from your response to my piece:
“But what photons cannot do, once they are swirling around inside the atmosphere, is influence the quantity of KE contained in it…because they are just swirling around…in and out of existence, much too busy conserving their own FIXED FUND of radiative energy.”
I just want to make it clear that when I was referring to the FIXED FUND of radiative energy I meant the fixed FUND of energy held collectively by all the swirling photons. I was seeking to distinguish this from the FIXED FUND of KE held collectively by all the molecules. I agree it’s a narrow distinction since the KE FUND exactly determines the corresponding radiative energy FUND! But I do very much see them being two separate FUNDs of energy – one possessed by molecules and the other by photons.
With the minor proviso that the fixed fund is actually KE plus PE …
No, I think you have missed an important point here. I know you are keen to remind people that PE is a much overlooked but intrisic and significant part of the energy balance in the atmosphere, and I applaud that completely. But in our model PE also possesses its own FIXED FUND.
We are talking (of course) about a steady-state model atmosphere which does not vary in its characteristics. In the aggregate therefore, whenever we take a ‘snapshot’ of the whole of the model atmosphere, we will find it has separate FIXED FUNDS of KE, RE (radiant energy held by photons), PE, and LE (Latent Energy). Of course in regions of the real atmosphere, at different times of day or night, different seasons, etc., all these funds aren’t fixed at all. But on average they must be our model – otherwise there is no way forward to examine the Candidate A and B mechanisms in detail.
Talking about these separate FIXED FUNDS of energy is just an accounting exercise, if you like. To get anywhere quantitatively, we must be sure to keep our separate ledgers in order. To press the accounting analogy a little further, we must also not make the equivalent of the gross accounting error of confusing ‘cash flows’ with ‘cash balances’. Many a business has gone under by confusing the two. Using the word FUND was just my way of reminding people that the quantity of energy in the atmosphere is a very different beast from the quantity of energy flowing through it per second, even though both (in our model) are FIXED!
Interestingly, although we can relatively easily determine the FIXED FUND of KE in the atmosphere (just by measuring its temperature profile, and knowing the atmospheric mass, the earth’s geometry, and the gravitational constant), I am not so sure if there are such firm figures for RE, PE and LE.
But I suspect Tim Folkerts and/or SoD will oblige!
David.
Point taken and agreed.
For the purpose of illustration a steady state model is just fine.
No harm in separating the molecular KE from photonic KE either if you feel it helps the narrative.
Stephen, That’s good that we are in agreement – except (and, oh! how I do hate to niggle)… “photonic KE” is a horrible term for radiation, because radiation is the antithesis of kinetic energy. A photon containing a given quantum of energy is anihilated when it is absorbed by a molecule, which thereby increases its fund of KE accordingly. Likewise when a molecule spontaneously creates (emits) a photon containing a specific quantum of energy, it reduces its fund of KE accordingly.
Whats wrong with Radiant Energy? And I do rather like the snappy abbreviations: KE, RE, PE, and LE!
Photons carry momentum, which is important to remember in cases like scienceofdoom telling me I don’t understand heat transfer because I object to the idea that you could get “extra” energy out of a surface by adding radiative to non-radiative losses.
Potential energy is completely relative, the potential energy difference between a parcel at 11 km and a parcel at 11.00001 km is tiny, while the potential difference between the 11 km parcel and one at 0.00001 km is huge.
tjfolkerts says about the secondary evaporation/condensation cycle;
“Why must it make the atmosphere warmer???
This cycle merely moves energy around WITHIN the atmosphere. You can’t “rob Peter to pay Paul” and expect to come out ahead. ”
There is a time factor implicit in the cycle that makes all the difference.
The water drops forming (probably at night) are intercepted by the rising sun and evaporated for the second (or more) time.
A net cooling effect.
Later as night falls the latent heat is gradually released as vapour turns to water drops forming clouds keeping the atmosphere warmer than it would otherwise be.
A net heating effect approximately 12 hours later .
Whether the secondary cycle happens or not will change all other parameters such as radiative and convective transfer.
The 40 inches of rainfall equates to the primary cycle value of 80W/m2 but the secondary cycle if included will change that value.
Bryan said:
“There is a time factor implicit in the cycle that makes all the difference.”
The whole issue is about the time factor but one wouldn’t think so from all the convolutions that people go through.
The temperature that a surface beneath an atmosphere can reach at given level of energy input is directly related to the length of time that that energy is retained between arrival and departure.
There is more than one timescale involved because radiative and non radiative processes operate at different speeds.
Hence the need for a radiative diabatic loop and a non radiative adiabatic loop.
All that is required to negate any effect from GHGs is for another part of the system to change in the opposite direction to whatever the net effect of those GHGs actually is.
And that is exactly what happens for any internal system change that is not accompanied by an increase in mass, gravity or top of atmosphere insolation.
SoD says
“Bryan has now come to the party with:
Suricat points out that there is a secondary evaporation/condensation cycle taking place.
This must effect the temperature of the atmosphere making it warmer than it would otherwise be.
This in turn has an effect on the radiative values and other processes such as convection.
“Perhaps this is why sceptics have little regard for diagrams like KT 2009 ”
“Bryan explains he is unhappy with KT2009 because the values are wrong, but he neglects to tell us what the correct values are.”
SoD previously failed to answer my question about the atmospheric window;
Is it 40W/m2 or the 63W/m2 proposed revised value or somewhere in between.
Why not measure it with a pyrgeometers with its plus or minus 12W/m2 uncertainty?
The claimed accuracy of most KT 2009 numbers is unwarranted
Who knows what the correct values are?
I think with the cloud variability that you have essentially a chaotic system that is beyond all but the roughest of estimates and even that is probably claiming too much.
I agree With David wholeheartedly. There is far too much of a shotgun approach to this topic. If I had my way we would take David’s points on one at a time, ‘A’ then later ‘B’, and dissect each one. Others here might later add a ‘C’ and ‘D’ but it would be great if we could stay more focused.
He mentions a 160 year span and I might instead say more like a 1000 years for if we can’t precisely understand just why our climate system is so damn stable we have a hard time looking deeper into the smaller variances and terms. It’s usually best to handle the largest variable first and the smaller later after the large ones are well understood. I have suggested that same approach over the last few years on wuwt but to no avail. Maybe we could do better here.
TB, how about a thread one at a time?
As for SoD, I’m not going to respond, he’s made it more that clear why he comes here and it is not to think and learn and that is why I am here, new and better science, I’ve heard everything he has to say at least a hundred times over. You don’t’ have to belittle each and every person here, Max knows the Stefan-Boltzmann relation and each type of heat transfer has an equation. Every single person here knows the atmosphere is not in TE but most is in LTE, it seems it is you that does not know that they all know.
I hate to argue, I consider everyone’s words and try to read between the lines and make them make sense and be correct if possible no matter how strange or terrible they were worded, many of us do not have silver tongues, so SoD, I would appreciate the same right back from you if TB decides to bear your presence.
Tim writes: “one at a time”, that would be a yarn.
Bit like herding cats, sense x and off they go. I am sure we could try. Chat about this via email seems sensible. I’ll use the given address.
tchannon says, January 9, 2013 at 9:48 pm: Tim writes: “one at a time”, that would be a yarn. Bit like herding cats, sense x and off they go. I am sure we could try. Chat about this via email seems sensible. I’ll use the given address.
Actually, it was Wayne, not Tim Folkerts, that said that in his fullsome and much appreciated response to my comments earlier.
I have often felt that it would be better to interact by email with just a few ‘select’ people. But the problem is it is then not an open forum and can easily get much too introspective. We need the interaction with people who don’t agree with us!
Perhaps the answer is to have a forum where everyone can read what’s going on but there are much stronger rules about how to moderate people such as Max who, whilst I am sure well meaning, really don’t know what they are talking about much of the time and won’t listen to good advice.
It seems like SoD and Tim Folkerts have been driven away by such behaviour, JUST when we need their input (and knowledge) to create a constructive bridge between those who are inclined towards skepticism and those who are inclined towards warmism.
For example, some time back on the other thread, Tim Folkerts and I were doing just fine, fighting our corners on whether the temperature of the earth is determined by ‘Throughput Throttling’ or ‘Output Throttling’. But aimless talk, there as here, appears to have driven our friendly and polite opponents away and terminated an important debate.
Sad days…
[Reply] There’s some back history. I agree with Wayne’s assessment of why S.o.D was here. It wasn’t for constructive/collaborative debate with a view to real progress.
You may well be right. SoD is strange.
But Tim Folkerts isn’t – at least not in his courteous behaviour on the other blog trail. It’s sad to see him disappear. We do need to engage with technically able warmists if we are to make progress. I learned a lot myself from my interations with him.
David, please don’t get me wrong, I have absolutely no problems with TimF, don’t always agree but that’s new a different thoughts. Tim led me to toss that 2/3 I was searching for in that former thread and to instead look elsewhere, guess what, it leads backwards to an even stranger heat capacity that plays right into what you are proposing to discuss of energy transfer in the troposphere. Water follows RE > PE (latent) > upward > KE > RE spread across the entire vertical column it seems or maybe that last KE never occur and it goes directly to RE, or both, or we still don’t really know. Have never heard an answer to that but I for one want to know. Each of these steps being taken just seems to make it clearer and clearer. I do understand SoD’s reason to stop the questioning but science goes nowhere without each questioning their own and everyone else’s thoughts. Every breakthrough had most wrong.
tchannon’s right, separating those two aspects would not be much of a discussion, I just jumped on it before thinking on the two, for the basic of what you are proposing is so right. Let’s get into the details you are speaking of.
“…people like Max who, whilst I am sure well meaning, really don’t know what they are talking about much of the time and won’t listen to good advice.” ~David
‘What do you mean “you people”?’ ~Tropic Thunder
Uh, what good advice are you talking about? If you mean “read up on the subject”, I do, have, and would anyway.
If you’re talking about the top post, I didn’t make it, I just pointed out that the use of black for the ocean gives an impression which could be avoided by simply not using the same color as one from the legend.
As for the “really don’t know what they are talking about much of the time”, I often make use of socratic irony in an attempt to get others to see where certain ideas may lead. If someone can’t explain an idea to one who is uninformed, they probably do not understand that idea very well.
This thread is now getting unwieldy to load on low power machines, and seems to have reached a natural pause. Please could Wayne and David propose a new thread with a clearly laid out starting point and an objective summary of where it came from, and maybe even where you want it to go? 🙂
tjfolkerts says: January 8, 2013 at 6:35 pm
“No, that is not particularly a good point. Yes, such things definitely exist. But that only transports energy WITHIN the atmosphere. Since “within the atmosphere” is not to the ground nor to space, there is no place for it in the KT diagram.”
I disagree tjf. What this does hi-light is the difference between ‘SH’ (specific humidity) at higher altitudes and lower altitudes, thus, WV at higher altitudes (lower SH) needs to be ‘recycled’ to keep up with the rate of energy transport set by surface evapotranspiration.
WV is active up to, and into, the tropopause intersection. Are you re-writing ‘the science’ to claim that “IR radiation resulting from WV condensation ‘doesn’t’ escape the atmosphere as OLR to space”? If so, I can’t agree. WV probably has a ‘spectral signature’ for the IR that it radiates at ‘STP’ (standard temperature and pressure), but for lower temperatures and pressures this would be both ‘specialist knowledge’ and ‘hard to detect’. Heck, it’s hard enough even to find the ‘density’ of WV for most enquirers, when it doesn’t exist as a stable ‘singular’ gas at STP (it’s ~3/5 the density of air).
In the past, I’ve received data from Ferenc Miskolczi (BTW, he’s not answered my mail yet wayne [if this is the correct thread]), which I’ve lost during my change of address, that shows a ‘warming kink’ in the ‘ELR’ (environmental lapse rate) from surface to ‘~low cloud base’ altitude. IMHO, this indicates that IR from WV condensation ‘does’ extend to the surface and the condensate ‘may’ eventually fall as a ‘fog’ (cloud scenarios can be difficult to predict and the ‘understanding’ for them is complex and limited). If you can’t accept that statement, google for ‘DLR from soot’ and you’ll probably come up with something you can digest better on the same principle, as I don’t have Ferenc’s data at hand.
However, getting back to the main point. ‘RH’ (relative humidity) is generally assumed to be ‘constant’ for a region at that region’s altitude and topography. A paper was produced by the UK Met Office on this subject many years ago, but has been ‘unavailable’ to me, for some time, since the (multiple) ‘makeover’ of their website, and I’m not aware of any other inquiry of such nature.
RH is difficult to measure to any great degree of accuracy (it alters so quickly) to arrive at a ‘regional/global’ average, but is not expected to ‘change’ for a region due to the physical topological characteristics imbued to the region. What does change quite a lot (which can be more easily followed) with a ‘warming/cooling’ scenario, is “RH/’SH’ (specific humidity) if the sample rate for SH is of a sufficiently short time-scale.
When we ‘know’ that the scarcity of WV in the ‘upper atmosphere’ (troposphere) necessitates the ‘recycling’ of WV to keep up with the ‘evaporative energy transport’ (from the surface) that ‘radiative transport’ can’t expedite (MEP being applied here), why don’t we just look at the ‘SH quantum at altitude’ of WV to gauge the intensity of global ‘warming/cooling’? It’s a ‘sensitive’ indicator with an acceptably ‘smoothed’ reactance/product for this purpose. SH at altitude ‘increases with a warming scenario’ and ‘decreases with a cooling scenario’. Heck, the IPCC even considered altering the ‘standard altitude’ of the ‘tropopause’ near the end of the last warming scenario!
With the ‘best intent’, I don’t understand how ‘average global precipitation’ can offer a result for a ‘warming/cooling’ scenario. The ‘definition’ just isn’t there (we don’t have the ‘precipitation recorders’ at enough sites to record an accurate ‘global’ data set). 🙂
tjfolkerts says: January 8, 2013 at 6:35 pm
“Similarly, the KT diagram summarizes global averages, so transport from equator to poles is also not included. Yes, climate models include such things; no, this very basic summary does not.”
Who mentioned “climate models” tjf? Certainly not me! I’ve ‘climbed into’ these ‘beasties’ before and found that their claims of “uses FORTRAN 98 [or whatever]” are belied by the associated compilers using a ‘plethora’ of ‘compiler languages’ with hardly a mention of the ‘assembly language’ for the ‘host’ system. This is a ‘sore’ subject.
However, the “KT diagram” certainly does cover ‘global’ energy transport from ‘the surface to space’. Thus, also includes any energy transport from the ‘equator’ to the ‘poles’ (albeit an intrinsic quantum). How can you justify this disaffection/dissociation with a ‘global model’ tj?
Best regards, Ray.
PS. Sorry for the slow response. I’ve been away helping an ‘old buddy’ who fell sick and needed my help. 😦
Ray,
Specific Humidity near the tropopause is precisely the metric I homed in on as being of high importance. What I found was that the Sun controls this:
Roger,
I agree. We mustn’t allow ourselves to lose sight of the positives here. I would be happy to re-cast my various (longish!) blog responses both here and on the Tim Folkerts thread into a simpler, more coherent header article, if that would help. But I couldn’t do it before next week. Happy also to pass it by Wayne before publication for a bit of pal review 🙂 if you think that would be helpful.
David: That would be great. I think a new thread from each of you would be best, and I’ll moderate more stringently than usual to keep them on track.
David, thanks, I’d be happy to but I also think it is unnecessary, you’ve got a good handle on the questions and limits of the atmosphere and radiation and what is actually occurring though we both still seem to have the same questions as you raise about the how the ToA and radiation and the KE in temperatures operate. Like everyone else I find I’m still changing my viewpoint on various topics as new evidence is realized.
Don’t know if I get a vote, but Stephen Wilde put forth this: “A relates to the vigour of convection and the speed of the water cycle.
B relates to the improved radiative capability of an expanded and so less dense atmosphere.” and it seems like a good topic for discussion to me.
Max: yes, you get a vote.
That specific humidity v sunspot data is interesting.
There is clearly a link but I think sunspots would more likely be a proxy for other solar variations such as the mix of wavelengths and particles.
I see that specific humidity increases when the sun is active so that would be a more active water cycle dumping more condensation beneath the raised tropopause.
When the sun is less active the slower water cycle dumps less condensation below a lower tropopause.
One can easily discern the effect of low solar cycle 20 amoungst the more active cycles either side and it shows that the current cycle 24 is lower than cycle 20 was.
The chances of the fit being that good across so many cycles by coincidence is virtually zero.
Thanks Stephen, you are one of the few people who have offered any analysis of that plot in two years of touting it around. I think it is of fundamental importance, but apparently few others are willing to think out of the box about it.
Ray, I read your recent comments (https://tallbloke.wordpress.com/2012/12/14/emissivity-puzzle-energy-exchange-in-non-vacuums/#comment-40401), but I am not really sure what your main objection is. You seem to be addressing something completely different from what I was saying.
I was specifically addressing KT diagram and what it does and does not show. Bryan thought that the omission of evaporation/condensation cycles WITHIN the atmosphere “illustrates how ‘dodgy’ some of the KT2009 figures are”.
The KT diagram shows only net values averaged over large areas (the whole earth) and over long times (a year or so). Furthermore, there are only 4 “objects” in the diagram:
1) the sun
2) the earth from the surface down (including land and ocean)
3) the atmosphere as a whole
4) space
The diagram shows the important energy flows between these 4 “objects”. It does NOT show energy flow within a single “object”. So evaporation/condensation that occurs WITHIN the atmosphere is not shown because it does not transport energy to one of the other 3 “objects” (which was the original point). The diagram also does not show convection within the atmosphere nor ocean currents within the ocean nor many other flows within the “objects” . This is not an “error” in the diagram. It does not make the numbers “dodgy”.
*********************************
That said, energy transport within each of the 4 “objects” is indeed interesting and complex and important.
So when you say things like:
“Are you re-writing ‘the science’ to claim that “IR radiation resulting from WV condensation ‘doesn’t’ escape the atmosphere as OLR to space””
that is a different issue. Certainly IR from water vapor to space exists — it would be part of the “169 W/m^2” from atmosphere to space, and hence it is already part of the KT diagram.
Max says, January 10, 2013 at 2:13 am: “…people like Max who, whilst I am sure well meaning, really don’t know what they are talking about much of the time and won’t listen to good advice.” ~David…‘What do you mean “you people”?’ ~Tropic Thunder. Uh, what good advice are you talking about?
Hi Max,
First of all, I didn’t use the phrase “you people” which would be ‘talking down’ and very rude.
I did use the phrase “…people like Max who, whilst I am sure well meaning…etc.” but I meant it only in the context of the discussion you had been having with Tim Folkerts and SoD about a fundamental Law of thermodynamics (the S-B Law), the only extended discussion of yours that I had been following closely. I apologise if that context wasn’t made clear.
But that spat you had is worthy of further consideration because it is an object lesson for us all: not to bang on endlessly without listening carefully to what your opponent is saying. I have found that, very occasionally, they are actually correct!
To recap…it had been asserted that a body at a given temperature (say T1) radiates energy at a rate (say R1) according to the S-B Law, irrespective of any other ways it may also be shedding energy (e.g. conduction or evaporation of water).
You took exception to this assertion because you knew (correctly) that the 1st Law requires that input and output energy flow rates are equal. You reasoned (correctly) that any input energy flow that was diverted through an additional non-radiant output channel would necessarily result in a reduction in the outflow of radiant energy, say down from R1 to R2. So you felt very strongly (and again correctly) that a body at temperature T1 and a power output R2 would violate the S-B Law.
What you had failed to realise was that the reduction in radiative outflow down from R1 to R2 would mean that the body would re-stablise at a lower temperature T2 such that T2 and R2 would still satisfy the S-B Law exactly.
Patiently, Tim F, SoD and others including me, tried our best to put you right several times. But, it appeared to me that, instead of stopping to think through what we were saying, you just bashed on using more and more irrelevant thermodynamic detail to try to bolster your (logically flawed) case.
Max, this was never an argument about thermodynamics at all. It was an error in logical thinking that we all make from time when pondering the multivariate world of thermodynamics. Just think of the mental wrestling we have all had to go through at one time or another with the Gas Law (PV=nRT) which has 5 related variables. I have felt at times that it is like juggling with jelly. 🙂
Ok, except, you’re essentially stating that emissions determines temperature, aren’t you?
David,
I have not skipped out on this discussion. But I am busy with other things. And sometimes if gets old responding to the same old issues over and over.
But you have a few new things, so let me take quick stab at some of them.
First, I am not sure what Trenberth (or others) may have said on this. I keep seeing “hints” or “hopes” that this is true, but I still haven’t seen any link to any direct quote about this.
ASSUMING that he has revised the “atmospheric window” upward, it does not necessarily follow that this will cause the up and down to balance. There are an infinite number of ways to re-balance the numbers. There are 4 different inputs to the atmosphere and 2 different outputs, and these could be adjusted in various ways to balance all the energy flows and still have a net upward radiation.
(I DO wish that Trenberth discussed the numbers in the diagram a little more. There is no mention in the paper of the “atmospheric window”, nor the mysterious “30 W/m^2” from the top of the atmosphere.)
The thing is, pretty much anyone acknowledges that the atmosphere is cooler than the surface. The only way to make the “residual” (ie the net energy flow between surface and atmosphere) zero, is for there to be zero flow of energy from warm to cool — which can only happen for “perfect” insulation! And there is definitely not perfect insulation there!
But the “colossal fund” of thermal energy in the atmosphere is NOT fixed.
____ Δ(colossal fund of thermal energy) = (energy in) – (energy out) ___
The whole idea of global warming is that these “colossal funds” in the atmosphere and surface are NOT fixed, but are slowly increasing.
Yes, we SHOULD be beguiled! 🙂
Radiation *IS* part of the energy INTO the atmosphere (both directly from the sun and from the surface).
Radiation *IS* part of the energy OUT OF the atmosphere (both directly to space and back to the surface).
As such, radiation DOES affect the thermal energy balance in (and the hence the temperature of) the atmosphere.
As we have just seen, this question itself is wrong. There is no ‘fixed fund’. Changes in the input or the output do indeed change this ‘colossal fund’. In the case of GHGs, they reduce the output to space, causing the temperature to increase until the balance is restored. But the balance is restored with a new, larger amount in the “colossal fund”, corresponding to a new, higher temperature.
I just noticed that I had actually misread part of your post.
I did not feel that a body at T1 and radiant output R2 would violate SB.
I felt (correctly) that a body at T1 and total output of: (non-radiant output) N1+ (radiant output) R1 would violate pretty much everything you can think of.
I also felt (correctly) that a body at T1 with total output of: (non-radiant output) N1+ (radiant output) R2 would not violate anything.
…
The “you people” is a joke from a movie Tropic Thunder, by the way.
Ultimately this is what I take issue with:
“What you had failed to realise was that the reduction in radiative outflow down from R1 to R2 would mean that the body would re-stablise at a lower temperature T2 such that T2 and R2 would still satisfy the S-B Law exactly.” ~David Socrates
I take issue because it is the same as saying “emissions determine temperature”, and while it might seem sensible to think this, it isn’t a matter of my failing to realize this is how it works.
It’s a matter of my coming at this from more of a physics background, and failing to see how this doesn’t amount to production of energy from nowhere.
A body radiating into a vacuum can be approximated by the SB law, and from that one can determine the minimum temperature which can give a certain level of emissions.
If a surface is emitting 396 W/m^2 then you can safely say it is 289 K or warmer.
If a surface has other processes transporting energy away from it, conduction/convection/evaporation being the important ones here, then the total energy removed from the surface by all processes can not exceed the total energy a black body would radiate at that temperature.
If it could be that way, then you could generate infinite power by simply exposing a surface to a vacuum, warming it up, then immerse it in an atmosphere and collect the full power emissions+energy lost through convection/evaporation.
____________________________
I assure you, this is not merely a matter of my logic being flawed, or my understanding being incorrect, it is a matter of my not being willing to accept a perpetual motion machine as a realistic description of the atmosphere.
A surface at 289 K in a vacuum would lose 396 W/m^2 as a black body.
A surface at 289 K in an atmosphere like our own would lose 97 W/m^2 from convection and evaporation.
If the losses from convection and evaporation do not reduce the emissions, then that surface is losing a total of 503 W/m^2 while the input is only sufficient to raise the temperature to 289 K.
Max says: ” … the total energy removed from the surface by all processes can not exceed the total energy a black body would radiate at that temperature.”
I am also coming at this from a physics perspective, and I can tell you (once again) that is is the wrong conclusion. You could correct this if you wrote something like:
“…the total energy removed from the surface by a̶l̶l̶ ̶p̶r̶o̶c̶e̶s̶s̶e̶s̶ radiation can not exceed the total energy a black body would radiate at that temperature.”
Max says: “I assure you, this is not merely a matter of my logic being flawed, or my understanding being incorrect, it is a matter of my not being willing to accept a perpetual motion machine as a realistic description of the atmosphere.”
And I assure you that this IS merely a matter of your logic being flawed. There is no perpetual motion machine hiding here!
Max theorizes:
“A surface at 289 K in a vacuum would lose 396 W/m^2 as a black body.
A surface at 289 K in an atmosphere like our own would lose 97 W/m^2 from convection and evaporation.
If the losses from convection and evaporation do not reduce the emissions, then that surface is losing a total of 503 W/m^2 [actually, that would be 493] while the input is only sufficient to raise the temperature to 289 K.”
No. For a surface at 298 K in a vacuum, you would need a 396 W/m^2 heater to maintain the temperature.
In the second condition, the input (the 396 W/m^2 heater) is NOT sufficient to maintain the temperature to 289 K. The imbalance of 97 W/m^2 would lead to cooling of the surface — the extra radiated energy comes (temporarily) from Q = mc ΔT until the temperature drops, eventually reaching a point where the net (radiation + convection) is again 396 W/m^2. Perhaps that would be 60 W/m^2 of convection and 336 W/m^2 of radiation (277 K)
Or you could increase the input from the heater to 493 W/m^2 so the surface could be radiation 396 and convecting 97.
Either way, there is no violation of conservation of energy, nor any perpetual motion machine.
Hi Max. You can consider this the other way round. You could say that if the surface is radiating at a rate commensurate with its temperature and its also losing 97W/m^2 via other processes for a total of 503W/m^2, then in order to stay at 289K it must also receive 503W/m^2
That would be 170W/m^2 from the Sun and 333 ‘back radiation’
Now, if 97W/m^2 is lost by convection and thermals, then 406W/m^2 is radiated as LWIR. About 60W/m^2 of that escapes through the ‘window’ which leaves 346 to be absorbed in the air. Half of that gets re-radiated downwards which is 173W/m^2. Added to the 170 from the Sun is 343W/m^2 and that appears to leave a deficit of 160W/m^2.
How the 173W/m^2 manages to rev itself up to 333W/m^2 is a mystery only AGW experts can fathom.
We now await clever people with spreadsheets to explain where we went wrong.
tallbloke, it depends on where vertically you are going to list the up and down radiation portion of the IR. If you pick the very bottom few meters then use the 333 wm-2 but you will never get a logical balanced spreadsheet out of that. Or, you can pick a location within the atmosphere where the upward and the downward IR are equal. IR downward from the ToA is minimal and IR downward from just above the surface is maximal so there IS a mathematical point in the middle of the troposphere where they must precisely balance and that is my spreadsheet above.
Don’t let TimF get you confused. He’s trying hard right now in his last two comments. First trying to make David Socrates a foolish know-nothing, twice, and then Max and it is him instead that sometimes is making no sense.
SoD was nice enough to answer my question on this topic, from which altitude is the 333 measured from … the 396 & 333 (which are both unrealistic) only exists right at the surface. Tim also has never replied for I fear it blows his idea of all of that IR energy “up there high in the atmosphere”, and it is not.
So, Tim is right in the bottom few meters, ~333+161-97=396 and your RE in those meters of altitude are correct and balanced there, but only there. That should make him happy. But I though we have speaking of the entire atmosphere as a whole and that gives a much different picture of the numbers.
However, no one should take my mid-atmosphere balance sheet above and try to lower it to the surface and make sense if it as Tim seems to be doing, or, you will not end up with enough radiative density to maintain the surfaces temperature… he was right there.
David Socrates is correct on his more or less Prevost photon gas view in the low boundary layer minus the radiation that is not in the GHG’s lines, bands and continuum and it is in this selective radiative equilibrium where the 396 and 333 exists, but only there.
Yeah, tb, I’ve tried to work it around all sorts of different ways, ultimately the easiest resolution I can find is that treating the different components of the radiation vector separately gives nonsensical conclusions.
Similarly, treating a surface in contact with an atmosphere as though it is a black body radiating into a vacuum produces nonsensical conclusions.
______________
We are told the average surface temperature is 289 K.
If a surface in a vacuum radiates 396 W/m^2 and a surface in an atmosphere radiates 396 W/m^2, where does the energy for conduction/evaporation come from?
Good catch on the math, was talking when I posted and wrote 503 for some reason.
tallbloke 1:28am:
I agree with wayne 3:09am. To break down wayne’s Trenberthian 333 into Stephen’s adiabatic loop 80+17 add the + 78 solar = 175 “absorbed in atm.” then becomes ~tb emitted downward 173.
80+17+78 + 158 = 333 atm. absorbed then emitted down (including added 158 Stephen’s diabatic loop) TOA down balance*
In words: thermals + LH + solar absorbed + TOA balance = 333 DWIR ~measured by ESRL give or take clouds, spatial and temporal stuff going on minute by minute, month by month.
As Tim F. wrote, I also wish Trenberth paper detailed the 333 better. Plus I agree with Tim F. if move the window from 40 to 66 the rebalancing is not so obvious; lotsa’ different ways to rebalance.
*TOA down balance from plugging: 396 – 158 plug + 1 = 239 (the +1 absorbed) voila. The -158 plug + 1 = – 157 I use for DWIR in the heat eqn. netted from +396 up to get 239-239=0 for near surface Tavg. 289K which should help Max at 3:11am, dunno.
Simple, not easy.
Wayne says: “Tim also has never replied for I fear it blows his idea of all of that IR energy “up there high in the atmosphere”, and it is not.”
Wayne says: “However, no one should take my mid-atmosphere balance sheet above and try to lower it to the surface and make sense …
True! And consequently no one should try to take your mid-atmosphere balance sheet and try to lower it to the surface and expect it to make sense for the emissivity (or any other parameter) at the surface. You cannot, for example, conclude that the surface emissivity is ~ 0.7 based on your mid-atmosphere balance sheet.
Wayne says: ” But I though we have speaking of the entire atmosphere as a whole … ”
In what sense? Even if you average around the earth and average over time …
* there is no temperature of the “entire atmosphere as a whole”.
* there is no single upward IR radiation of the “entire atmosphere as a whole”.
* there is no single upward convection of the “entire atmosphere as a whole”.
All of these (and more) depend on the altitude. If you are talking about such parameters, you HAVE TO consider how they change with altitude (or admit that the model is too simple to make accurate predictions).
Wayne says: “First trying to make David Socrates a foolish know-nothing, twice, … ”
No, simply pointing out what I consider errors in thinking. This is moderately advanced science and there is no shame in making mistakes on the path toward understanding. Understanding comes from defending your ideas against direct criticism (or accepting that the criticism is well-founded). I think David & I are having a constructive conversation and I don’t think think of him as a fool at all.
Wayne says: “… and it is him instead that sometimes is making no sense.”
Care to give one specific example for us to discuss? I am sure there are points I have made that could use some clarification so that people can understand them better.
Ultimately here is the biggest problem which seems to be ignored.
A surface can emit less radiation than a black body without cooling to a lower equilibrium temperature, and emissions do not determine temperature.
If a surface receives 396 W/m^2 and loses 396+97 W?m^2, it will cool off, right?
How much kinetic energy would a surface need to possess to lose 396+97 W/m^2?
Thanks all for the excellent replies to my provocative comment. I agree with Wayne that only very near the surface is the 333 going to stack up. But lets not forget water vapour recondenses high up and radiates strongly to space from there. Downward component won’t get back to the surface in any great amount because convection is ever upwards. David’s ‘prevost energy’ was first mooted here last year by commenter Mydogsgotnonose in this thread:
Well worth a read.
So the radiative measurements are mainly a convenient measurement of the expression of temperature by the constituents of the climate system, ocean, air, and clouds. The main reason for these constituents being at their respective temperatures is their heat capacity, and their location within the pressure gradient determined by gravity. I feel that we are getting nearer to specifying a model which will more successfully generate emergent properties which better match the real world than radiative models are able to.
David wisely said: “To press the accounting analogy a little further, we must also not make the equivalent of the gross accounting error of confusing ‘cash flows’ with ‘cash balances’.”
I see this distinction needing to be made again. The “cash balance” is the thermal energy in the system, which depends on heat capacity and temperature and mass. The “cash flow” is the heat moving between different regions, which depends on emissivity, surface area, thermal conductivity, and temperature (and other factors relating to eg convection and evaporation and incoming sunlight).
The tricky part is probably that temperature is a key factor in both the “cash balance” and the “cash flow”.
Max said:
“If a surface receives 396 W/m^2 and loses 396+97 W?m^2, it will cool off, right?
“it will cool off” relates to the “cash balance”.
“receives 396 W/m^2 and loses 396+97 W?m^2” relates to the “cash flow.
If the object continues to have a negative “cash flow”, then the “cash balance” will indeed decrease (the temperature will fall).
“How much kinetic energy would a surface need to possess to lose 396+97 W/m^2?
“How much KE” relates to the “cash balance”
“to lose 396+97 W/m^2” relates to the “cash flow.
You can’t directly compare the two. No amount of stored KE will allow the object to lose 503 W/m^2 and not cool off. On the other hand, a very small amount of stored KE will allow the object to lose 503 W/m^2 and not cool off IF you have some other 503 W/m^2 heater supplying energy to the surface.
Tallbloke says: ” The main reason for these constituents being at their respective temperatures is their heat capacity, and their location within the pressure gradient determined by gravity.
Here temperature is a proxy for “cash balance”, and in that context the “current cash balance” is indeed strongly related to heat capacity, gravitational compression, and temperature.
But the “current cash balance” will change based on the “current cash flow”. “Cash flow” has very little to do with pressure or heat capacity.
You need to consider BOTH of these ideas. Radiation balance & the KT diagram summarizes the “cash flow”. As such, it MUST be part of any theory trying to explain climate and climate change.
PS I hate using “KE” to denote the thermal energy. “Kinetic energy” is usually reserved for bulk motion. As long as we recognize that “KE” here means “random thermal KE of individual molecules or atoms” then I can grudgingly live with this nomenclature. (Note also the the random thermal energy of rotation & vibration must also be included somehow.)
tallbloke says: January 10, 2013 at 8:10 am
“Ray,
Specific Humidity near the tropopause is precisely the metric I homed in on as being of high importance. What I found was that the Sun controls this: (graphic included).”
Hm! Well, yes. Sol does control the amount of ‘WV’ (water vapour) in Earth’s atmosphere, but the graphic comparing ‘ssn’ with ‘total column SH below 300mb’ is; 1) difficult to read, as the two plots/graphs are overlaid, and 2) it’s impossible to co-relate the two plots against each other because the data from one is taken from a different system to the other with many ‘attractors’ operating independently within each system, though with ‘some’, apparently, ‘shared’ by each system.
Time for some detective work. To prove that this isn’t just a ‘coincidence’, you’ll need to show the link where energy transfer is the causal factor and is a true ‘correlation’ (my punctuation ‘sucks’, but I’m tired). 🙂
What are the ‘participants’ (attractors that control the energy leaving/entering “the system” [AKA systemic ‘boundary losses/gains’]) that alter the “total column SH below 300mb”?
1) Thermal energy within ‘neighbouring’ systems that ‘bleed’ into/from the “system”.
2) The ‘ave. lifetime’ expectancy of WV within the system under observation.
3) Conditions which alter the ‘ave. lifetime’ expectancy of WV within the system under observation (e.g. GCRs and other CCN products).
4) Thermal input/output to/from the system under observation (this will start as the surface, but must also include laterally advected products (that penetrate the column boundary) and vertical input/output from above and below [much as in “1)”, but at altitude]).
5) Molecular property changes caused by their related ‘temp and pressure’ at ‘attitude’ (a lot of chemistry is dependant on a ‘given’ temp and/or pressure).
This is all I can think of at the moment, but I’m almost sure there are more ‘attractors’ involved here. Whatever you can think of for a scenario, there’s usually more to it than you first thought of. 🙂
You then need to undergo the same assessment for ‘ssn’ and hi-light the strength of connection between the two systems that you want to ‘co-relate’. If you ‘can’t’ do this, it’s nought but a ‘coincidence’ and the ‘correlation’ isn’t there. 😦
That isn’t to say that I can’t help you with this at some time TB. 🙂
If you want this, I’ll help as best I can. E-mail me if you want to.
Best regards, Ray.
Tim, what I was getting at is what temperature is: a quantity related to the energy and degrees of freedom in a given sample.
Temperature is not exclusively related to the radiated energy/degrees of freedom, so naturally I have trouble seeing why certain claims are made.
Can anyone tell me why there would be the same energy radiated for a surface in a vacuum as one in an atmosphere–if both have the same temperature–and yet the surface in an atmosphere has more energy available for other forms of heat transfer?
If you set up two surfaces, one in a vacuum, one in an atmosphere, raised the temperature of both to 289 K, measured that both were emitting 396 W/m^2, and noted that the surface in the atmosphere also loses 97 W/m^2 from convection/evaporation… what would happen if you switched the surfaces?
Would the surface that was in an atmosphere no longer have the “extra” 97 W/m^2 once it was placed in a vacuum?
Would the vacuum surface gain this energy it did not possess in the vacuum?
If this is energy leaving the surface, it must be an intensive property of the surface, if it is not actually coming from the surface than where is it coming from?
Max says, January 11, 2013 at 12.05am: Ok, except, you’re essentially stating that emissions determines temperature, aren’t you?
MAX: Not at all. I suppose that the way I wrote it you might have thought that that was what I was suggesting, but it was just my careless writing. So let me re-phrase it more carefully:
“What you had failed to realise was that the increase in output flow due to the additional non-radiative output channel would lower the FUND of KE stored in the system to the point where its corresponding temperature dropped to a value T2 such that T2 and R2 would still satisfy the S-B law whilst still also satisfying the 1st law.”
A bit more unwieldy but logically and physically correct.
Max says, January 11, 2013 at 12:53 am: I did not feel that a body at T1 and radiant output R2 would violate SB…etc
Max,
Tim F (January 11, 2013 at 1:24 am) has reponded to you in detail on your contiinuing mis-conception. I completely endorse what he has said.
Max says, January 12, 2013 at 8:03 am: If you set up two surfaces, one in a vacuum, one in an atmosphere, raised the temperature of both to 289 K, measured that both were emitting 396 W/m^2, and noted that the surface in the atmosphere also loses 97 W/m^2 from convection/evaporation…
Max,
You keep setting up impossible conditions and then drawing logical (but incorrect) inferences.
In your example, if both your surfaces are at a temperature of 289K, one could not output a total of 396Wm-2 of power while the other output a total of 396+97 = 493Wm-2 of power unless their input powers were different: 396Wm-2 and 493Wm-2 respectively.
Surely you can see that both the 1st Law and the S-B law must be satisfied by any model you care to construct.
ALL,
In my view, we have got to get agreement on this. These are very fundamental tenets of thermodynamics to have a disagreement about. The implications go far beyond climate science. If Max turns out to be right it will undo 163 years of progress in physics (1st law of thermodynamics – Clausius 1850; Stefan-Boltzmann law – 1879). The least he could do for us would be to arrange for us to have prominent seats at his Nobel Prize ceremony. 🙂
More seriously, without general agreement on this, here in our more modest forum (even if Max alone perversely continues to disagree), I think it will be very difficult to move forward in these discussions.
What do other people think?
“What you had failed to realise was that the increase in output flow due to the additional non-radiative output channel would lower the FUND of KE stored in the system to the point where its corresponding temperature dropped to a value T2 such that T2 and R2 would still satisfy the S-B law whilst still also satisfying the 1st law.” ~David
Hmmm, we are starting out with a temperature that is assumed to be stable at 289 K, aren’t we?
If the total power leaving a surface includes all the channels, radiative and otherwise, then we can balance the TFK2009 diagram without needing to invent a way for atmospheric DWIR to add energy to the system.
As I am confident that DWIR merely reduces the loss due to UWIR, that could actually work out fine.
So if you have 160 direct shortwave reaching the surface and 97 leaving through non-radiative methods we have 63 left, oh, and look at that, it is exactly the amount left over if one subtracts DWIR from UWIR in the TFK2009 diagrams.
Ultra-simplified TFK2009 diagram:
340 in_______________340 out (239 radiated + 101 reflected)
_______________________
____________________78 solar SW + 160 ground (atmosphere budget)
__ 101 reflected__________
____________________97 thermals/evaporation
_______________________
160 solar at surface ___ 63 up from surface (net LW)
Oops, was supposed to be 79 solar SW, was trying to get the spacing right.
Max #
David Socrates says: January 9, 2013 at 11:12 am
As I have been saying repeatedly on this blog trail and on the Tim Folkerts one, having read the K&T 2009 paper recently I was impressed that Trenberth et. al. appear to have done the best job possible with the limited data then available.
But what exactly was their “job”?
“ … what I was getting at is what temperature is: a quantity related to the energy and degrees of freedom in a given sample.
Temperature is not exclusively related to the radiated energy/degrees of freedom, so naturally I have trouble seeing why certain claims are made.”
…
Max seems to be addressing the td aspects that I raised earlier on degrees of freedom. That is but one of the relations we have that must be met, the potential temperature equation. The other is the ideal gas law, both must be met simultaneously so you have at least two simultaneous equations to solve.
David and anyone also:
Φe = 288.15 * (P/101325)^(287.05/1508), that matches the standard atmosphere.
Like:
288.15 = 288.15 * (101325/101325)^(287.05/1508) at the surface.
216.77 = 288.15 * (22700/101325)^(287.05/1508) at the troposhere.
P/ρ = R*T must also be met like:
101325/1.225 = 287.05*288.15 at the surface.
22700/0.3648 = 287.05*216.77 at the tropopause.
or better:
Te = P/ρ/287.05
288.15 = 101325/1.225/287.05 at surface.
216.77 = 22700/0.3648/287.05 at the tropopause.
These must match at all levels in between, both of them, if the standard atmosphere close to the real atmosphere and by the radiosondes I look at daily, it does.
There is another:
Γ = -0.0065 K/m
T = 288.15 + h * Γ
There, now we have three relations that must simultaneously match everywhere in the troposphere and of course the 1st law, 2nd law, S-B, and other constraints, they must all be respected.
That was my entire point in raising the potential temperature relation (the Poisson equation) was to add to the list. But Φe is a bit curious, see the Cp in the exponent of Rs/Cp? It is 1508 J/kg/K that matches the standard atmosphere. But, 1003 J/kg/K is the value listed of the specific heat capacity in most tables you see, not 1508 J/kg/K. So, for some reason, there is also this extra 505 J/kg that is needed to raise the temperature one degree Celsius at every point in the troposphere.
What is it? I have yet to answer exactly what that means. It is evidently water related (latent heat) but does that mismatch cause excess radiation? Maybe.
One thing I suspect is that radiation is not isotropic at every level. It seems spherical near the surface and growing elliptical up to the tropopause and I cannot find a reason that this cannot be so, for the density is always lower when higher. Think of each GHG molecule as a tiny broadcast station or CB antenna and look at the broadcast pattern vertically.
Geesh… I didn’t even check those equations I just typed in… let me know if any are vary far off, they should all be very close for those are the two ends of the linear relation in each case.
Also, the Brunt–Väisälä frequency relation seems to be yet another that might need to be met and is the tie right back into the gravitational field. I’m looking into this one.
(http://en.wikipedia.org/wiki/Brunt%E2%80%93V%C3%A4is%C3%A4l%C3%A4_frequency)
But I’m like David, the troposphere seems to be all td in structure but what are the equations or relations that tie these equations into the radiative aspects that, of course, are present and of vital importance in two prime places, the surface and the boundary layer, and the tropopause and above. Right there is what I am currently searching for and those ties might be rather hard to find. Radiation properties across a varying pressure, density and temperature field seems to be hiding. 😉
David Socrates says: January 9, 2013 at 11:12 am
As I have been saying repeatedly on this blog trail and on the Tim Folkerts one, having read the K&T 2009 paper recently I was impressed that Trenberth et. al. appear to have done the best job possible with the limited data then available.
I agree David. I could find no gaping holes in the base data but it is just what that cartoon did to so many minds and imaginations as if the IR section was “up there high in the atmosphere”. If you compare TFK’s to Miskolczi’s to the five or six other energy budgets you get a range of each core parameters that are all in a +/- 3 to 4% range, sometimes even closer, and that shows just how loose the accuracy is in our measurements gathered so far… none of them match each other very close.
In that comment above, I forgot to mention something about that cp of 1508 J/kg/K. The ~1005/1508 is the 2/3 that led me, wrongly it now seems, down that path trying to see if this 2/3rd was evident in the other planet’s atmospheres but that now seems to be the 1/3 greenhouse factor (503/1508) you don’t find on Venus and Jupiter… it’s the water vapor and the state change, the other two planets don’t have that.
Also, I said that cp “maybe increases the radiation” and it equally might mean “possibly decreases the radiation” due to that abnormally high cp specific heat capacity. I didn’t mean to leave out one of the possibilities.
Re. tjfolkerts says, January 11, 2013 at 12:44 am (referring to my posting of January 9, 2013 at 11:12 am)
Tim,
It’s really good to see you back. I at any rate always value your contributions here. And, yes, I agree that having to reply over and over to the same point sometimes makes this seem too much like hard work. I also have a ‘day job’, hence the significant delay in responding.
As always your comments have provoked considerable thought. Here are my responses:
1. TRENBERTH DIAGRAM You are right to be cautious over whether Trenberth et. al. have actually agreed that the atmospheric window value should be 63Wm-2 rather than 40Wm-2. It was Christopher Game who made the assertion (July 21, 2010 at 11:01 pm in http://scienceofdoom.com/2010/07/17/the-amazing-case-of-back-radiation/ ) that he had conducted a private correspondence with Trenberth about it. Does anybody know how to contact Christopher?
2. RE-BALANCING THE NUMBERS You say: ASSUMING that he has revised the “atmospheric window” upward, it does not necessarily follow that this will cause the up and down to balance. There are an infinite number of ways to re-balance the numbers. There are 4 different inputs to the atmosphere and 2 different outputs, and these could be adjusted in various ways to balance all the energy flows and still have a net upward radiation.
Wrong! If you did balance the 23Wm-2 change from 40Wm-2 to 63Wm-2 in any other way, the overall 396Wm-2 figure for upward radiation would change to 396+23 = 419Wm-2, wouldn’t it? This would then change the reference surface temperature value of 288K of the Trenberth steady state model. Sorry, but you have inadvertently strayed into Max’s ‘logical mis-reasoning’ territory…
3. NET ENERGY FLOW FROM SURFACE TO ATMOSPHERE You say:The thing is, pretty much anyone acknowledges that the atmosphere is cooler than the surface.
To respond meaningfully to this comment, I have to presume you are talking about the part of the atmosphere that is actually at the surface – because, as we climb further up, the gravity-induced negative lapse rate guarantees that the air does indeed get progressively cooler than the surface.
I offer the following rather detailed analysis for your consideration:
(a) Firstly, consider the case of that portion of the air actually in contact with the surface that is thermally heated by conduction from the surface, accounting for 17Wm-2 of KE flow. That air is by definition at the same temperature as the surface because only an infinitessimally small temperature difference can exist across an infinitessimally thin interface.
(b) Secondly, consider the case of the water vapour at the surface, generated from surface water by evaporation. That process accounts for a transfer of 80Wm-2 of KE from the surface into latent heat of vaporisation. A change in the temperature of that water vapour at the surface is of course ruled out by the physics of the type of energy transformation involved. But, interestingly, this transfer of KE to latent heat does nevertheless cause a kinetic energy budget imbalance: the surface delivers KE but the air at the surface does not gain KE. So this can hardly be argued to be a process that makes the water vapour cooler when it is the surface that is losing KE!
(c) Thirdly, in the case of net upward radiation (if there is any at all, see points 1 and 2 above) it is true that the net flux of photons emanating from the surface (if any) will be absorbed as KE by molecules at varying heights above the surface, although mostly the absoption will be very close to the surface because there is a rapid reduction in the fraction of absorption with increasing distance from the surface. The consequence of this ‘spread out’ absorption of radiation, if anything, will (theoretically) be a very slight temperature inversion! In practice, of course, this is completely overwhelmed by the lapse rate which (whatever its exact value) is strongly negative in comparison to this extremely small positive tendency.
Bottom line? There is no significant difference between the surface temperature and the air temperature at the surface. That’s my bet.
Discuss, but please not for too long! This issue of a possible slight temperature difference between surface and air at the surface is a very marginal part of the argument.
4. THE RESIDUAL RADIANT ENERGY FROM THE SURFACE You say The only way to make the “residual” (ie the net energy flow between surface and atmosphere) zero, is for there to be zero flow of energy from warm to cool — which can only happen for “perfect” insulation! And there is definitely not perfect insulation there!
You have misunderstood my use of the term ‘residual’. Take another look at the context of my remark. I was talking about the radiation residual (if any). I never suggested that the total net energy flow from surface to atmosphere could possibly be zero. That would be absurd. And I only suggested that the net radiative contribution would have to be zero (for the reasons elaborated in point 2 above) if a revision of Trenberth’s figure from 40Wm-2 to 63Wm-2 is agreed. If is not agreed, the net radiative contribution will of course remain at 23Wm-2.
5. COLOSSAL FIXED FUND OF KE You say The whole idea of global warming is that these “colossal funds” in the atmosphere and surface are NOT fixed, but are slowly increasing.
I repeat, the Trenberth work is a steady-state model. It may well have been produced in the context that Trenberth is a nororious AGW alarmist but so what? The Trenberth diagram is not actually about global warming and should surely be addressed on its own merits. It is about energy flow balances as measured in the current earth-atmosphere system. And because it is a model, it does not claim to take account of all the multifarious perturbations that may occur in the real atmosphere, nor in particular does it address the consequences of making a change to the composition of the atmosphere such as the addition of GHGs.
The whole objective of the Trenberth model is to establish an agreed starting point (a bit like the US Standard Atmosphere) from which such discussions about perturbations and changes can thereafter be sensibly conducted.
6. BEGUILED BY RADIATION AS MAGIC DUST You say: Yes, we SHOULD be beguiled! radiation *IS* part of the energy INTO the atmosphere (both directly from the sun and from the surface). Radiation *IS* part of the energy OUT OF the atmosphere (both directly to space and back to the surface). As such, radiation DOES affect the thermal energy balance in (and the hence the temperature of) the atmosphere.
I thought I had made it crystal clear that radiation was an essential ‘transport and transformation element’ of the whole energy cycle, where I wrote: At the interfaces with space, photons do have vital roles to play: (1) The transport of energy through the vacuum over large distances (Sun-to-earth; atmosphere-to-space). (2) The transformation of energy (radiant-to-KE on input; KE-to-radiant on output) via GHG molecules.
Of course it is the radiation in from the Sun than warms the both the surface and the atmosphere. And of course it is the radiation out to space from the atmosphere that stops the earth heating up indefinitely. And of course GHGs are essential to implement that transformation. Everyone understands that.
The context in which I made my remark about not being beguiled into thinking that radiation was some kind of ‘magic dust’ was in terms of the radiation in the bulk of the atmosphere. That radiation is doing neither of the above things. It is just doing what radiation always does: photons are buzzing around being emitted and (very quickly indeed) anihilated – simply as a consequence of (not as the creator of) the FIXED FUND of KE that exists in the bulk of the atmosphere. In short, radiation is doing nothing whatsoever to warm the bulk of the atmosphere. It is just a natural consequence of the fact that the bulk of the atmosphere is already warm, kept so by a FUND of KE that is at a level FIXED by the rate at which ‘top up’ KE energy passes through it.
7. FIXED FUND OF KE IN THE ATMOSPHERE You say: As we have just seen, this question itself is wrong. There is no ‘fixed fund’. Changes in the input or the output do indeed change this ‘colossal fund’. In the case of GHGs, they reduce the output to space, causing the temperature to increase until the balance is restored. But the balance is restored with a new, larger amount in the “colossal fund”, corresponding to a new, higher temperature.
Please first review my response at 5 above.
The whole point which you appear to have missed is that, in the absence of any of the changes that might be suggested, such as a change in the Sun’s input or a change in GHG concentration, the FUND of KE must indeed be FIXED. If there are no changes in conditions, why will the FUND of KE change? That is surely the model we are trying to agree upon, including Trenberth’s flow figures, before we move forward to debate the two mechanisms I have outlined, one favoured by you, the other by me, either of which could be the cause of restricting the energy through-flow, and thus controlling the level of the FIXED FUND.
That was the key point of my posting and the one you have so far failed to respond to…
MOVING THE FOCUS OF THE DEBATE
So perhaps you would now like to respond to the last part of my posting where I suggested moving the focus of the debate to try to resolve whether the true cause of atmospheric thermal enhancement is due to resistance in the energy flow path (‘THROUGHPUT THROTTLING’) or resistance in the KE-to-radiation transformation mechanism at the ToA (‘OUTPUT THROTTLING’).
I had thought over the past few weeks we had reached a point where that was the only real subject of disagreement between us. Now, reading your latest set of objections, I am having doubts that we are getting anywhere at all. Please reassure me. 🙂
“Wrong! If you did balance the 23Wm-2 change from 40Wm-2 to 63Wm-2 in any other way, the overall 396Wm-2 figure for upward radiation would change to 396+23 = 419Wm-2, wouldn’t it? This would then change the reference surface temperature value of 288K of the Trenberth steady state model. Sorry, but you have inadvertently strayed into Max’s ‘logical mis-reasoning’ territory… “ ~David
Uh, what did you just do?
The surface is at 288~289 K, theoretically it could emit up to 396 W/m^2.
Some of those emissions should pass through the atmosphere directly into space.
If the original value was 396-40 direct to space and the proposed new value is 396-63 direct to space, why are you adding that energy on to the original black body value?
Wouldn’t that energy have to be removed from some other part of the budget?
Setting aside that the overall figure for upward radiation is not 396 W/m^2, as it should be 396-DWIR, which works out to 63 W/m^2 using the TFK2009 values, which is oddly the same value as the proposed larger “window”.
…
As for the infinitesimally thin layer above the surface, if you consider the same temperature difference at ever shorter distances from the surface, the transfer of energy by conduction grows rapidly.
You can use that to set an upper bound, i.e. it is impossible for there to be 0.1 K difference at 0.001 cm or something like that because it would imply thousands of W/m^2 transferred through conduction.
The 17 W/m^2 value by itself is all but worthless without knowing what temperature difference and altitude this transfer is taken to occur at.
[Moderation note] Max, your superscript (TM) on your name handle is causing issues with wordpress. Please change it. Thanks – Rog
David:
1 & 2: Atmospheric Window. Rebalancing the numbers to match a higher loss through the atmospheric window could be done a variety of ways — none of which are very appealing because they would all entail changing numbers in the Trenberth paper in ways that would seem to go against theory and/or experiment.
In any case, until we have actual evidence (rather than a second-hand claim in a post on a blog) that such a change exists, this is not really worth worrying about.
3. NET ENERGY FLOW FROM SURFACE TO ATMOSPHERE. No, I was talking about the temperature “where in the downward IR originates”. This is anywhere from 0 m to several km up. My “pretty much everyone acknowledges” comment relates to
> some people don’t know that
> there are inversions, but that will not change the overall average temperature difference.
4. THE RESIDUAL RADIANT ENERGY FROM THE SURFACE
You say “I was talking about the radiation residual (if any).
I was also talking about the radiation residual.
It doesn’t matter which form or energy transfer we are talking about – heat moves from warm regions to cooler regions unless the two are isolated from each other, ie unless there is “perfect insulation” between them. The only two ways to prevent any heat transfer via radiation between the atmosphere are
a) they are the same temperature.
b) they do not exchange photons.
6. BEGUILED BY RADIATION AS MAGIC DUST
David says ” In short, radiation is doing nothing whatsoever to warm the bulk of the atmosphere. It is just a natural consequence of the fact that the bulk of the atmosphere is already warm, kept so by a FUND of KE that is at a level FIXED by the rate at which ‘top up’ KE energy passes through it.
Perhaps this is more of difference in perspective or wording than a difference in understanding.
If the boundary conditions are set (albedo, thermal IR out, … ), then the conditions WITHIN the atmosphere are pretty well set, independent of the presence or absence of GHGs. GHG’s do little to affect the lapse rate or the temperatures once we know the flow of energy out of the top. In this sense, radiation has little to do with temperatures within the atmosphere.
But the boundary conditions depend on the GHGs. Add more GHG and you throttle back the thermal IR leaving the TOA. The resulting imbalance forces the atmosphere and the ground below it to warm up. In this sense, the GHGs have a HUGE impact on the temperature.
Consider an analogy — a tank that has 240 liter/min flowing in, and 240 liter/min leaking out. The depth of the water in the tank will be fixed at some level where the pressure is large enough to cause the 240 l/min to leak out (if the tanks was less full, the leak would be less and the tank would get fuller). You could say that the pressure at the bottom of the tank is a natural consequence of the depth of the water, and the flow rate in or out doesn’t matter. But I could say that the leak DOES matter — if I plug part of the leak, the water will rise to a new, higher level and the pressure will be greater. The leak and the pressure are connected — just like the thermal “leak” and the temperature of the atmosphere are connected.
‘THROUGHPUT THROTTLING’ vs ‘OUTPUT THROTTLING’. This is an interesting place to focus. I suspect that we could think of GHGs as the “output throttle” and the various feedbacks as the “throughput throttle” (or perhaps as an “input throttle” in the case of albedo changes). As such, all three throttling mechanisms are important.
Max says, January 13, 2013 at 2:05 pm: Uh, what did you just do? The surface is at 288~289 K, theoretically it could emit up to 396 W/m^2. Some of those emissions should pass through the atmosphere directly into space. If the original value was 396-40 direct to space and the proposed new value is 396-63 direct to space, why are you adding that energy on to the original black body value? Wouldn’t that energy have to be removed from some other part of the budget?
Max,
I was NOT proposing adding the additional 23 on to the radiation figure of 396 to make 419. In my posting, the italicised words are those of Tim Folkerts, not me.
I am arguing the opposite, that if 23 is added on to the atmospheric window radiation channel, the ONLY place from where the 23 can be legitimately subtracted is the 356 portion of the radiation channel, bringing it down to 333. If you do that, the total radation from the earth’s surface would then remain at 396 as it must do if it is to represent the correct surface temperature of 289K.
On the other hand,, if you follow Tim Folkerts’ original assertion to which I was replying, and subtract the 23 from one or more of the NON-radiative flow channels, this would indeed leave you in a great mess because the overall upward radiation figure would then indeed have gone up from 396 to 419, the latter figure representing a surface temperature of 293K which is completely wrong.
So it looks as if, for once, you and I are in violent agreement. 🙂
Max says:
As for the infinitesimally thin layer above the surface, if you consider the same temperature difference at ever shorter distances from the surface, the transfer of energy by conduction grows rapidly.
No it doesn’t. If the flow rate is 17Wm-2 then that is the quantity of power being conducted per square metre through the surface, whatever thickness of conduction path you choose to examine.
You can use that to set an upper bound, i.e. it is impossible for there to be 0.1 K difference at 0.001 cm or something like that because it would imply thousands of W/m^2 transferred through conduction.
I am sure you are correct. But nobody except you is postulating such a high temperature gradient. You just made that up and it obviously isn’t remotely true. So where does that get us? In reality, the gradient is whatever it is (consistent with conducting 17Wm-2) and not what you arbitrarily say it is.
The 17 W/m^2 value by itself is all but worthless without knowing what temperature difference and altitude this transfer is taken to occur at.
For the reasons above this is not a meaningful statement. Do you have a better value than Trenberth’s 17Wm-2? I don’t.
Tim,
Thanks for your responses. Briefly in reply:
1 & 2: ATMOSPHERIC WINDOW: I do not believe you can arbitrarily subtract the 23Wm-2 added to the atmospheric window from one or both of the non-radiative flows without changing the surface temperature from Trenberth’s 289K. It would be useful if you would now at least acknowledge this simple mathematical reality so we can set the issue to one side. I do agree that it is not worth pursuing the AW issue any further unless and until we get confirmation from Trenberth et. al. that the change to the value is generally acceptable.
3. NET ENERGY FLOW FROM SURFACE TO ATMOSPHERE: OK we are in agreement that the atmosphere above the surface is cooler than the surface. Hooray!
4. THE RESIDUAL RADIANT ENERGY FROM THE SURFACE: If we are indeed both talking about the radiation residual of 23Wm-2, then this is soon absorbed as KE and will then, of course flow from hotter to colder areas by the normal process of molecular diffusion. So what’s there to disagree about!
5. COLOSSAL FIXED FUND OF KE: I noticed you skipped this one. The essential question to answer now is: do you agree that the Trenberth diagram is meant to be a steady-state model, rather in the same way as the US Standard Atmosphere, representing the earth-atmosphere system as it is now with its FIXED FUND of KE etc., so that we can use it as a reference standard against which to judge future perturbations such as a doubling of CO2?
6. BEGUILED BY RADIATION AS MAGIC DUST: It appears that we are in agreement on the main point, that the FIXED FUND of KE in the atmosphere is not heated by the radiation that necessarily accompanies it.
Beyond that, the final issue now is what does maintain the FIXED FUND of KE and therefore the current atmospheric temperature profile? Is it my choice of THROUGHPUT THROTTLING (slow convection, etc., not sensitive to GHG concentrations) or is it your choice of OUTPUT THROTTLING (controlled by GHG concentrations at the ToA). As I have said, I think this is where we will have to get quantitative because qualitative arguments back and forth are not going to resolve this one way or the other.
17 W/m^2 is the energy being conVECTed, not conDUCTed. Conduction itself is VERY small!
> Thermal conductivity is ~ 0.025 W/(m*K)
> Lapse rate is ~ 10 K/km = 0.01 K/m
Thermal conduction is ~ 0.025 W/(m*K) * 0.01 K/m = 0.00025 W/m^2 upward through the atmosphere. Stated the other way around, if you have even a mW of heating per square meter upward through the atmosphere, you will have convection, and that convection will hold the lapse rate to ~ 10 K/km.
We could invert the calculation above and find that the gradient for conduction alone would be about 40 K/m for each W/m^2 of energy transferred by conduction. For dark surfaces on sunny days, there could indeed be a significant gradient in the first couple millimeters. But other than that very thin layer, conduction itself will be small and convection will keep the gradient below ~ 10 K/km.
David asks: “The essential question to answer now is: do you agree that the Trenberth diagram is meant to be a steady-state model, rather in the same way as the US Standard Atmosphere, representing the earth-atmosphere system as it is now with its FIXED FUND of KE etc., so that we can use it as a reference standard against which to judge future perturbations such as a doubling of CO2?”
I think the diagram is meant to summarize current actual conditions. So it is not really a “model” but a summary. It does give numbers for various energy flows early in the 21st century that could be compared to the same flows at other times, so in that sense it is a “reference” for later comparison.
On the other hand, it is clearly not meant to be steady-state, since it lists a “net absorbed” of 0.9 W/m^2. Now, this is a relatively small imbalance, but the thermal energy in the system would NOT be fixed with his numbers. Thermal energy and temperature would necessarily be increasing.
Tim Cullen says, January 12, 2013 at 12:41 pm: David Socrates says: January 9, 2013 at 11:12 am: “As I have been saying repeatedly on this blog trail and on the Tim Folkerts one, having read the K&T 2009 paper recently I was impressed that Trenberth et. al. appear to have done the best job possible with the limited data then available.” But what exactly was their “job”?
Tim,
Thanks for your question.
Their job was to review from several sources all available analyses of the various fluxes and consolidate them all into the famous “Trenberth Diagram” as explained in their paper available here:
Click to access EarthsGlobalEnergyBudget.pdf
It seems that most of the figures are from satellite instrumentation which has its limitations of accuracy but is at least solidly empirical data. At the surface-atmosphere interface, however, the figures are probably more speculative. I suspect that the downwelling figure of 396Wm-2 has simply been calculated from the known mean global surface temperature using the Stefan-Boltzmann law. This has probably been done by several of the authorities on whom K&T have relied for all their data. Although theoretically calculated, it is a value that is difficult to argue with because the earth is known to be a good approximation to a black body radiator peaking in the longwave region.
Some people believe that the diagram is nonsense because it contains an apparent near-circularity in the surface-atmosphere radiation budget (396Wm-2 up; 333Wm-2 down) rather than being expressed as a single net-upward value of 63Wm-2. In my opinion, skeptics have done themselves no favours by criticising this. The atmosphere very near the surface and the surface itself are both ‘bodies’ at approximately the same temperature. So, in conformance with the S-B law, they would be expected to radiate towards each other at nearly the same rates. So it is not un-physical to express these two flows separately in the diagram.
I think that the K&T figures are the “best show in town” not because I can vouch for their veracity but because, reading their paper, I get the feeling they have probably done a better job than others who have produced similar diagrams and who mostly remain anonymous. U
nless that is that you know of any other groups who have published similar detailed papers to the K&T 2009 one?
Tim,
You say: 17 W/m^2 is the energy being conVECTed, not conDUCTed. Conduction itself is VERY small!
Agreed with all you say. In part 3a of my comments I was of course referring to ‘conduction/convection’, or ‘conduction/diffusion’ as it is sometimes described, where the ‘conduction’ bit is purely a microscopic surface phenomen followed by macrosopic convection.
Interesting calculation of the miniscule (and entirely unmeasurable) rate of conduction up the atmospheric column. You also make a theoretically important point about the lapse rate being independent of the rate of energy flow, however small the latter is.
Having thought about this a bit more, I wonder whether the microscopic surface ‘conduction’ part is anyway better described better described not as conduction but at the statistical thermodynamical level in terms of molecular interactions. It would be interesting to pursue this, although it’s not really a relevant subject for this thread.
http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/heatra.html#c3
“In ordinary heat transfer on the Earth, it is difficult to quantify the effects of convection since it inherently depends upon small nonuniformities in an otherwise fairly homogeneous medium. In modeling things like the cooling of the human body, we usually just lump it in with conduction.”
Further: http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/bodcon.html#c4 ~Conduction calculator
http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/bodcon.html#c3 ~Wall thickness discussion
“While the assumption that the temperature drops from 34 C to ambient air temperature in a distance of 5 cm for still air is nothing more than a guess, it does serve to point out this important concept. If a fan were blowing air over the skin, stripping away the warmed layer of air, the conduction loss would be significantly greater. This can also be discussed in terms of convection.”
David Socrates says: January 13, 2013 at 10:20 pm
Thank you for the link…
David Socrates says: January 13, 2013 at 10:20 pm
Unless that is that you know of any other groups who have published similar detailed papers to the K&T 2009 one?
Personally, my value judgement is that they did the “best job possible” back in 1993:
Chapter: Radiation budget at the top of the atmosphere
By: Edwin F. Harrison, Patrick Minnis, Bruce R. Barkstrom and Gary G Gibson
Atlas of Satellite Observations Related to Global Change
1993 Cambridge University Press
Other than the units chosen, that one isn’t too different from mine: http://i341.photobucket.com/albums/o396/maxarutaru/science/daynightbudget_zps55e9bde5.png is it?
[ Thank you Max over encoding –Tim]
Hey Max, care to explain your diagram?
* Where does the 391 J (day) and 345 J (night) “available at surface” come from? Clearly it is not sunlight since it exists almost as large at night. Does that include back-radiation?
* Where do the “conduction” numbers come from? They are ~ 70% higher than Trenberth.
* Where do the “latent heat” numbers come from? They are ~ 15 % higher than Trenberth.
* Where do the “absorbed by atmosphere” numbers come from? Is that IR going up? IR going down? sunlight going down? If is it upward IR, then it is about 50% as large as Trenberth.
* Where do the “emitted by atmosphere” numbers come from? They are ~ 20% lower than Trenberth.
* Where does the 66 W/m^2 “direct to space” come from? Why is it the same on the warm side and the cool side?
On the day side, the surface is apparently sending 35 + 108 + 182 = 325 W/m^2 to the atmosphere, but the atmosphere only emitting 179 W/m^2 from the top. What happens to the other 325-179 = 146 J each second into each square meter? Even on the night side, the atmosphere is apparently absorbing large amounts of heat.
*The surface temperature at .95 emissivity.
*Conduction and Convection were calculated from here: http://upload.wikimedia.org/wikipedia/commons/4/47/NASA_earth_energy_budget.gif
*Latent heat taken from here: http://upload.wikimedia.org/wikipedia/commons/4/47/NASA_earth_energy_budget.gif
*Absorbed by gases with strong IR components.
*Emitted by atmosphere is what is required to balance the outgoing and incoming energy.
*The atmospheric window didn’t show much sign of variance over day or night from what I could determine so I worked the numbers out with it remaining mostly unchanged.
As for the last part you answered your own question, the energy which is not emitted directly to space is distributed towards the night side and poles, this is something I just took as a given.
Tim Cullen says, January 14, 2013 at 10:40 am: Personally, my value judgement is that they did the “best job possible” back in 1993:
Chapter: Radiation budget at the top of the atmosphere By: Edwin F. Harrison, Patrick Minnis, Bruce R. Barkstrom and Gary G Gibson Atlas of Satellite Observations Related to Global Change 1993 Cambridge University Press
Tim,
Re. the Trnberth and Harrison diagrams at:
Click to access EarthsGlobalEnergyBudget.pdf
OK, I translated the Trenberth et.al. (2009) figures into percentages so that I could make a realistic comparison with the Harrison et.al. (1993) ones. Trenberth first, followed by Harrison in square brackets:
INCOMING RADIATION FROM SPACE…
Incoming SW radiation reflected straight back to space 30% [30%]
Incoming SW radiation absorbed by atmosphere: 23% [19%]
Incoming SW radiation absorbed by surface: 47% [51%]
TOTAL 100%
OUTGOING RADIATION TO SPACE…
Incoming SW radiation reflected straight back to space 30% [30%]
Surface radiation to space 12% [6%]
Clouds to space: 9% [26%]
Non-clouds to space: 49% [38%]
TOTAL OUTGOING 100%
SURFACE TO ATMOSPHERE AND SPACE:
Surface evaporation to clouds: 23% [23%]
Surface sensible heat to non-clouds: 5% [7%]
Net surface radiation to atmosphere: 7% [15%]
My first impression is how remarkably similar most the the estimates are, considering there were 16 years between the two sets of figures. Not surprisingly, perhaps, the ins from space are very close because satellite instrumentation is the best way of ensuring accurate global averages.
The surface figures are less so, which again is not surprising because they are harder (if not impossible) to derive from satellite instrumentation and rely on various methods of surface measurements which are difficult to average acccurately over the earths whole surface. Evaporation is the exception here which is exactly the same in both cases. But this may simply indicate they used exactly the same source, there having being no improvement on this ‘guesstimate’ in the 16 years that had elapsed!
The values for Net Surface Radiation to Atmosphere and Surface Radiation to Space are almost reversed between the two sets. I would tend towards the later (Trenberth et. al.) figures simply because this seems to be the ‘direction of travel’. You may want to review some earlier discussions in this thread about speculative indications that the Surface Radiation to Space figure may be even higher at 18%. If so, this would practically eliminate the Net Surface to Radiation figure altogether.
So for the life of me, I can’t see why you would want to choose figures derived before 1993 over figures drived 16 years later. Unless you have an inside track that suggests otherwise?
Max, That diagram is outdated (the same point that David is making in other posts). NASA has a newer version that is more closely in line with Trenberth.
http://www.nasa.gov/audience/foreducators/topnav/materials/listbytype/Earths_Energy_Budget.html
Also, the 391 J (day) and 345 J (night) figures are not what is “available” but rather what is “required” to maintain the temperatures you site.
Slow your roll, 391 J/345 J is what the surface could emit as radiation at that temperature, emissions are determined by temperature, hence the layout of the diagram.
I’m not particularly concerned with being in line with Trenberth, probably why I didn’t do something ridiculous like arrange things to suggest the atmosphere provides twice as much energy as the sun does, huh?
I’m concerned with providing a plausible and realistic depiction of the energy flows in question, the values can be changed, but I contend that this is a far superior depiction of the information than the ridiculous Trenberthian format if only because I don’t leave room for one to erroneously conclude that sunlight is less powerful than atmospheric emissions.
Oops, left out “the 1.22×10¹⁷ Joules is what is required to produce the observed temperatures, I don’t know why you brought up ‘maintain’ as I clearly intended one to deduce that the diurnal variations are significant while the average remains the same”, that part is kinda important.
Max says: “Slow your roll, 391 J/345 J is what the surface could emit as radiation at that temperature, emissions are determined by temperature, hence the layout of the diagram.”
So why are you starting with what the surface COULD emit? Why not simply balance all the REAL energy flows?
At ~ 290K the surface DOES emit ~ 390 W/m^2 of thermal radiation. Period.
There is no subtracting other energy flows . You have to ADD other energy flows. During the day 391 J + 35 + 108 = 534 W/m^2 is leaving. If 66 escapes straight to space, then 534-66 = 468 is absorbed by the atmosphere! At night that becomes (345 + 23 + 85) – 66 = 387 W/m^2 absorbed by the atmosphere. (And this is perfectly OK — we have ~ 420 absorbed by the atmosphere from the ground and 80 absorbed by the atmosphere from the sun = 500 in. That is about the same as the amount leaving up and down from the atmosphere.).
Now, I could live with saying that there is only a net upward flow of (396 – 33) = 63 W/m^2 of thermal IR (give or take a little depending on whose numbers you use). If you want to subtract the downward IR from the upward IR, that is a legitimate calculation.
The simple fact is that all the energy flows in the Trenberth diagram balance (and all the energy flows balance in the diagram you started with). There are no violations of conservation of energy of the 2nd law of thermodynamics.
I now retire from trying to convince you further. David S & I have both pointed out several times the mistake of subtracting other energies from the thermal IR. If you haven’t learned by now, then I doubt you will. But at least hopefully we can prevent your ideas from spreading.
Max,
I endorse Tim Folkert’s comments 100%. The undoubted efforts you are putting into the question of energy balances will be wasted until you understand two thermodynamic fundamentals:
(1) A body at a given steady-state temperature radiates energy at a fixed rate as strictly defined by the S-B law, irrespective of what other non-radiative energy that body is also outputting; and irrespective of what radiative and/or non-radiative energy that body is receiving…the ONLY proviso being that the sum total of the input radiative and/or non-radiative energy flows MUST equal the sum total of the output radiative and/or non-radiative energy flows, as required by the 1st law.
(2) A body can reach ANY temperature irrespective of how much or how LITTLE energy is flowing through it…the actual determinant being the body’s physical characteristics that create a resistance to energy through-flow and therefore act as an energy accumulator.
Disbelieving statement (1) has caused you a lot of confusion and wasted your time and intellectual energy.
Disbelieving statement (2) has allowed you to deny downwelling radiation, and thus reject Trenberth’s energy flow diagram on the spurious and incorrect grounds that 396Wm-2 is bigger than the Sun’s net input power to the surface of 161Wm-2.
You now have one convinced warmist and one convinced skeptic both telling you the same thing. Notice also that nobody else has defended your position. Max, it really is time for a sober re-think.
All the best but…over and out!
So David Socrates, are you now saying you no longer believe in the coupling of surface radiation (CRCC) to the conduction, thermal and evaporative surface loss modes and now take Tim Folkerts long-time AGW stand that radiation has nothing to do with any other heat transfers occurring simultaneously from Earth’s surface?
Some refs you might consider before answering:
…
http://www.thermopedia.com/content/205/
“Coupled radiation, convection and conduction (CRCC) is a self-consistent heat transfer process by the mechanisms of thermal radiation, convection and thermal conductivity. CRCC occurs between a surface in contact with a moving medium and between various components of dust-loaded flows, the moving medium being considered not only as gas and plasma, but the condensed state as well.
Here, self-consistent heat transfer means, in essence, that each of the above-mentioned mechanisms influences to the same extent the energy balance inside and (or) on the boundary of the domain considered and thereby changes the energy exchange intensity by other mechanisms.
The combined action of radiative, convective and conductive heat transfer must be considered when solving a wide class of heat and mass transfer problems in such fields as power, aerospace and process engineering. These include: ….”
…
http://www.emis.de/journals/SMA/v02/a05.html
Click to access p05.pdf
EXISTENCE AND UNIQUENESS OF THE SOLUTION OF THE COUPLED CONDUCTION-RADIATION ENERGY TRANSFER ON DIFFUSE-GRAY SURFACES
Wayne, you misunderstand my position (and perhaps also CRCC).
All of the various heat exchange mechanism are important and all are indeed interconnected. I don’t deny that. So for example, if convection is increased in a system somehow (perhaps a fan is turned up), then (if the energy flow is held constant) the temperate will fall and the radiation will decrease by the same extent that the convection increased. This is in accord with what you quoted above: “each of the above-mentioned mechanisms influences to the same extent the energy balance inside and (or) on the boundary of the domain considered and thereby changes the energy exchange intensity by other mechanism.” But the surface STILL radiates according to the Stephan-Boltzmann Law. This increased convection doesn’t change the emissivity or anything like that. This increased doesn’t keep the temperature the same but rob energy from thermal radiation.
Or put another way, the Trenberth diagram already represents a coupled system, where changes in one energy flow will ripple through the other energy flows so as to either
* change the energy balance inside the system
* change the energy exchange by other mechanisms.
(Again, in accord with what you quoted above.)
tjfolkerts says
“Or put another way, the Trenberth diagram already represents a coupled system, where changes in one energy flow will ripple through the other energy flows”
The idea that the Trenbreth diagram is settled science with numbers derived to three significant number precision is far fetched.
Yet that is what is shown.
In no other branch of science or engineering would such sloppy work be taken seriously.
Any fraudulent accountant or tax dodger knows how to supply numbers that appear to balance.
Coupled with these two other ‘elephants in the room’.
1. The historical record shows no temperature increase link to increasing atmospheric CO2.
If anything CO2 is shown to lag increasing temperature
2. The last 16 years show no temperature increase despite significant CO2 increase.
Its time to drop the CO2 driven greenhouse gas catastrophe theory.
wayne says, January 16, 2013 at 7:42 pm:are you now saying you no longer believe in the coupling of surface radiation (CRCC) to the conduction, thermal and evaporative surface loss modes…?
Not at all. Quite the reverse. Tim Folkerts has beaten me to it in providing you with a correct and considered response.
If you carefully read the various extended discussions that Tim and I have both had with Max on this matter, the issue at stake is Max’s confusion over bodies (such as the earth’s surface) that emit radiation and also release energy by other means (e.g. conduction/convection and/or evaporation).
As I am sure you would agree, the sum of the radiant and non-radiant energy out-flow(s) MUST equal the sum of all the energy in-flows (1st law!), assuming of course that the body in question has reached a stable temperature.
Once that stable temperature has been reached, it must also be the case that the body’s temperature and the corresponding radiative out-flow conform strictly to the S-B law!
Regarding the Trenberth energy flow balace diagram, you can of course argue with the values assigned to the various energy flows but it is a fact that the diagram does balance in terms of both the 1st law and the S-B law.
That’s all there is to the debate with Max.
Bryan says, January 17, 2013 at 8:41 am: Any fraudulent accountant or tax dodger knows how to supply numbers that appear to balance.
Before you accuse Trenberth et. al. of an accounting scandal you should look at the physical realities. It would perhaps be helpful if you were to review more closely Tim Folkert’s and my various careful attempts during the course of this thread to explain how energy balance occurs in bodies (such as the earth’s surface) that output and receive energy by radiative and non-radiative means, requiring both the 1st law and the S-B law to be obeyed simultaneously.
That narrow issue is what the discussion with Max was about.
It is facile to suggest that Trenberth et. al. offer numbers to any particular precision. In their two published works (1997 and 2009) they were simply reporting on their review of the best available empirical evidence at the time. They actually state in their 2009 paper that it is not possible to assign uncertainties to the figures. In other words, they did a review of all the sources of information, and published their ‘best estimates’, ensuring of course that the various internal and external flows balanced according to known physical laws.
Please be assured that your anger at the ongoing global warming alarmist farrago is no stronger than mine. But also please don’t let that anger get in the way of persuing the actual science wherever it may lead you.
David Socrates
If you look at the KT 2009 diagram you will see that nearly all the numbers are quoted to three significant figures.
Examples 333 W/m2 and 396 W/m2 and so on.
There is no way that Climate Science values have anything like this level of precision.
For instance the a properly set up pyrgeometer measuring a real value of 100W/m2 would read it as anything between 83 and 93W/m2 by the most recent report.
In real science and engineering you are required not to claim more accuracy than you can prove.
For instance it is more likely that the above values should be reported as
3×10^2 W/m2 and 4×10^2W/m2.
It really is ‘how many angels dance on a pinhead’ time when you and Tim discuss whether the odd one or two W/m2 should be added or subtracted from a particular KT value.
The input and output Earth values should roughly match or else the Earth near surface temperature will VERY SLOWLY increase or decrease.
But isn’t that what happens all the time?
Also the energy circulating within the Earth system can be much larger than the input and output values.
So the fact that KT 2009 balance to the very last Watt per square metre ‘don’t impress me much’.
Bryan,
I agree with much of what you say but you have to understand the context of the discussion into which you interjected your observations. Of course the Trenberth estimates are very approximate because they depend on multiple third party sources that vary from one another and, for the reasons you say, these are each subject to significant error. But when people make their best efforts to produce a roughly approximate Earth Energy Balance Diagram they would surely have egg all over their faces if the numbers didn’t balance according to both the 1st law and the S-B law. 🙂
The conversation that both Tim Folkerts and I were having with Max concerned the physical principles invoved, not on the precision of their values (the latter being a perfectly arguable point). Max does not appear to believe the Trenberth diagram is right in principle because it includes so-called ‘back radiation’ and that is what we were arguing about.
In contrast to his viewpoint, I note that you say “Also the energy circulating within the Earth system can be much larger than the input and output values”. So it would appear that you support Tim Folkerts and me on this extremely important fundamental physical point about the distinction between energy flow rates through a system and the energy levels within it.
I’m not sure how I managed to so woefully misrepresent my point, my objection isn’t because of back radiation.
No, my objection is to the patently absurd idea that said back radiation can increase the energy available at the surface beyond the level at which it originally warmed the atmosphere enough for said level of back radiation to come into play at all.
Go get a dimmer switch equipped lamp and a mirror, turn the lamp on, put a mirror in front of it. The light bouncing off the mirror and striking the filament will do something.
If the the outcome is that the filament heats up, then if you had equipment sensitive enough to detect this change and adjust the controls of the lamp appropriately, could you turn down the power exactly enough that it still puts out the usual amount of light for less power?
Note that I’m not talking about simply gathering the light into a more focused state, rather I’m talking about shining the light emitted by a source directly back on the emitting surface.
Let’s set that aside though, because when you’re dealing with constant levels of power from internal energy sources there are all sorts of ways the discussion could go and most of them have little to do with the system we’re interested in: the surface of a rotating planet with an atmosphere like our own lit by a star like our own.
Simply put: you have a surface receiving energy as radiation (x_rad), it reaches a temperature t, and it loses energy through radiation (y_rad), conduction/convection (y_con), and evaporation (y_eva).
I am saying that x_rad > y_rad, because y_rad + y_con + y_eva probably shouldn’t add up to more than x_rad, should it?
“ CRCC is the most general type of heat transfer; in this general case of heat transfer in a moving medium, all the three mechanisms act. However (depending on medium temperature, velocity, density, geometry and optical and physical properties), it is possible for one or two mechanisms to dominate. In these limiting cases, heat transfer may be designated as “convective”, “conductive,” “radiative,” “conductive-convective,” “radiative-conductive” and “radiative-convective” heat exchanges.
When solving problems of CRCC in whichever mechanisms of the heat transfer are important, a useful first step is to determine the influence of radiation on the moving medium parameters. If this influence is small, one can simplify the problem, treating the medium motion and the radiation heat transfer separately. The problems are then solved successively by the methods for a moving media and for radiation heat transfer — the combined action of the mechanisms being taken into account using the additivity principle. In the case of such weak interaction account may be taken of the interdependency of the processes using perturbation methods. If radiative transfer influences strongly the medium’s thermal state and its motion, the additivity principle is inapplicable. This case is the most complicated one in the CRCC problem.
[…snip…]
[…]…is the radiation-convective parameter (to compare heat conductivity and radiation contributions into the process); Pe = Re · Pr is the Peclet number (to compare heat conductivity and convection), τ0 = L/l0 is the typical optical thickness, l0 is the mean free path to characterize radiation heat transfer. There are problems in estimating the latter value, since it characterizes the photon mean free path averaged over the entire frequency spectrum, while the spectral mean free paths vary a few orders of magnitude. The approximations of optically thin (τ0 <> 0) media are widely used in CRCC analyses, since they make it possible to avoid the solution of the transport equation (4). In particular, for τ0 <> 1, radiation flow can be represented in the Fourier law form
where http://www.thermopedia.com/content/4895/eqn1181.gif is the radiative conduction coefficient, with kp as the mean Rosseland coefficient.
If the medium is optically thin for certain wavelengths and thick for others, the above-mentioned approximations for the radiation flux and its divergence cannot apply. Instead, the transport equation (4) must be solved. For a highly-scattering medium, the integro-differential form of Eq. (4) must be solved and this makes the problem more complicated. The standard way to simplify the problem is to use assumptions on diffusional or δ-like character of the scattering and then to solve the problem employing diffusion approximation. This approximation appears to be even more justified in this case than in the nonscattering case, where it can also be recommended for application.” ~Surkjikov S.T. at http://www.thermopedia.com/content/205/
_____________________________________________________________________
If radiative transfer is significant in comparison to conductive and convective losses then it has to be accounted for properly and it’s not a simple matter of just adding values together when you’re dealing with equations for continuity, momentum, conservation, and selective transport of radiation.
if it is not significant than you can simplify the process and a more direct additive method will work… but if that is the case, whence comes the greenhouse effect?
John Socrates says
“…so it would appear that you ( that is Bryan) support Tim Folkerts and me on this extremely important fundamental physical point about the distinction between energy flow rates through a system and the energy levels within it.”
I also agree, energy flow does not have the same properties as energy content.
Kiehl and Trenberth 2008 said ” Kiehl and Trenberth (1997, hereafter KT97) reviewed past estimates of the global mean flow of energy through the climate system and presented
a new global mean energy budget ”
K and T present an “energy budget” of “flow” into, out of and within the atmosphere. This is wrong.
Flow into the atmosphere equal flow out because of Kirchoff’s Law.
Within the atmosphere the 1st law of thermodynamics applies to energy content not energy flows.
If I count bees entering and leaving a hive that does not tell about how many are inside.
Max asks how can we explain the greenhouse effect without considering radiation inside the atmosphere. Gravity redistributes the total energy, more at the bottom as less as you go up.
As I go up a mountain I don’t notice the effect of gravity change on me, I am nearly as dense as the earth. The air is much less dense, it is greatly affected by gravity, it get colder as you go up and its gets even less dense.
How do K and T make this mistake. I looked at their 97 paper. Probably not deliberate but very useful to demonise CO2, an IR active gas.
As usual with fundamental errors it happens very early, in the first paragraph.
They mention ” latent heat flux”.
The thermodynamic 1st law does apply to latent heat, it comes from a body, a mass of water vapor. It is comes out of the water vapor in an instant at a phase change. It is not a flux , it does not flow like radiation.
In the next sentence they mention ” shortwave and longwave surface fluxes.” The implication is that the 1st law applies these radiative fluxes also. It does not.
A mass property ( latent heat) is wrongly called a flux. Then a real flux ( surface radiation ) is wrongly given mass properties.
Mass and radiation have very different properties
Spot on Roger C
Roger Claque says, January 17, 2013 at 10:53 pm
Hi Roger,
Thanks. It is a relief to have some support and interaction after Max’s meltdown. But he is not alone in making such a fundamental mistake so it is very important here at the Talkshop get these ideas bottomed out. Hence my (and Tim Folkerts’) many continued attempts to explain his error to him.
I love the analogy with bees entering and leaving a hive. It’s a very succinct real-world reminder that flow through a system, and quantity within a system, are not the same thing at all.
Re, “latent heat flux”, I agree that converting Kinetic Energy from the surface to latent heat in rising water vapour is not a heat flux. But I suppose that it is often called that (rather sloppily) because, in the context of a convective atmosphere, there is an eventual transfer from the latent heat stored in the water vapour to Kinetic Energy in the atmosphere where the water vapour precipitates. That constitutes a transfer of KE from surface to atmosphere. That is the ‘flow’ of energy that K&T are attempting to quantify.
Re. “…a real flux ( surface radiation ) is wrongly given mass properties:, yes, yes and yes! It is the fixed fund of Kinetic Energy contained within the bulk of the atmosphere subject to gravity that gives it its temperature profile. The fixed fund of Radiation that is also present in the bulk of the atmosphere, buzzing from one GHG molecule to another, is simply a consequence of that KE, and not its cause as many people have been led to think.
Rather like imagining that the loudness of the buzzing coming from inside the hive is the cause, rather than the consequence, of the number of bees inside it!
David and Roger C: It’s a lovely analogy, and reminds me of summer, which is a nice thought on this freezing winters day. 🙂
Ever since commenter ‘mydogsgotnonose’ re-introduced the very old concept of ‘prevost exchange’ of radiative energy, I have characterised the situation as radiation ‘buzzing about in the atmosphere’ doing not very much in net terms until it reaches the TOA and emission gets to space.
I think we are ready for the summary post David keeps promising. 😉
A fundamental mistake…
Look at what you’re saying is a “meltdown” or “fundamental mistake” again.
Simply put: you have a surface receiving energy as radiation (x_rad), it reaches a temperature t, and it loses energy through radiation (y_rad), conduction/convection (y_con), and evaporation (y_eva).
I am saying that x_rad > y_rad, because y_rad + y_con + y_eva probably shouldn’t add up to more than x_rad, should it?
Spot on? Roger C’s comments are full of errors!
“Flow into the atmosphere equal flow out because of Kirchoff’s Law.”
No flow into the atmosphere (approximately) equals the flow out because the temperature is staying (approximately) the same.
Kirchhoff’s Law says the emissivity of the atmosphere = the absorbtivity of the atmosphere. The ‘purpose’ of Kirchhoff’s Law is to ensure there WILL be a flow from warm to cool (eg from the ground to the atmosphere, or from the atmosphere to space). If absorption and emission were not the same, then you could violate the 2nd Law.
“Within the atmosphere the 1st law of thermodynamics applies to energy content not energy flows.</i"
The first law is written as
ΔU = δQ – δW
so it is ALL about flow (changes) and NOT about content! Divide through by 'Δt' and the flow becomes even more obvious.
“As I go up a mountain I don’t notice the effect of gravity change on me, I am nearly as dense as the earth. ”
It is the fact that you are a solid that makes the difference noticeable, not the different densities between you & the atmosphere.
“The implication is that the 1st law applies these radiative fluxes also. It does not.
Shortwave and long wave thermal radiation are “heat” = δQ and hence ARE part of the 1st Law.
Max says: “I am saying that x_rad > y_rad, because y_rad + y_con + y_eva probably shouldn’t add up to more than x_rad, should it?
And you are right — but for the wrong reasons!
x_rad = energy received as radiation by the earth = (shortwave radiation from the sun) + (longwave radiation from the atmosphere) is indeed larger than the y_rad = energy lost by the surface.
Max: It doesn’t work like that. The system accumulates energy in the various components commensurate with their heat capacities, emissivities and the energy throughput in a dynamic system. They then express that energy level as a temperature, and they radiate in proportion to that temperature. The radiation doesn’t do much below the point where it can emit directly to space, because it cancels out by and large. But that doesn’t change the fact that things radiate in proportion to their temperature and emissivity, whatever else is going on in the way of other processes.
Tim F: So Kirchoff’s law is saying in will equal out, because absorbtivity and emissivity are equal, which is what Roger C said.
Tallbloke — no, (energy in by radiation) will only equal (energy out by radiation) if the two objects radiating to each other are the same temperature.
If a cloud at 260 K absorbs 90% as much energy at 10 um as a black body would, then the cloud at 260 K will also emit 90% as much energy at 10 um as a black body would. That is what Kirchhoff’s law says.
But the cloud will absorb more energy from the 290 K ground than it will emit to the 290 K ground. (Energy in) ≠ (Energy out).
An object will always have a new gain in energy by thermal radiation from warmer objects around it, and always have a net loss to cooler objects.
Tim F: My understanding was that Roger C was applying Kirchoff’s law to the Earth system as a whole – the view from outside, where Ein=Eout.
Within the system, all sorts of other factors Kirchoff, S-B et al never attempted to apply their formulas to come into play.
Even if he is applying energy conservation to the earth as a whole, (energy in) = (energy out) because temperature is (approximately) constant (and because there are no other major sources/sinks of energy). Kirchhoff’s law is ALSO true, but it is not the “cause”.
Or put another way, there are plenty of cases where Kirchhoff’s Law is true (ie always!), but temperature is NOT constant.
Tim says
flow into the atmosphere (approximately) equals the flow out because the temperature is staying (approximately) the same.
No, constant earth atmosphere temperature does not cause the equal energy and out.
Energy in = energy out at the top cause the constant temperature at the top. Gravity then causes the higher temperature at the bottom.
The first law is written as ΔU = δQ – δW
so it is ALL about flow (changes) and NOT about content! Divide through by ‘Δt’ and the flow becomes even more obvious
Yes thermodynamics is about energy changes . The 1st law says that during and after any change the amount of energy in joules ( J ) is constant.
Trenberths energy budget is in Watt/m2. A Watt ( W) is J/s.
ΔU = δQ – δW does not contain time term (t) in it.
Dividing through by time ( t) doesn’t improve the maths. It doesn’t make Trenberth’s diagram about change and so thermodynamic.
It make it wrong.
His energy budget diagram has 11 radiation items, but is only the thermals ( convection ) and latent heat that maintain the vertical temperature profile ( lapse rate ) and hence the surface temperature
Shortwave and long wave thermal radiation are “heat” = δQ and hence ARE part of the 1st Law.
Thermal radiation is radiation from hot things. It is still radiation not matter. If it hits matter then it heats matter, it becomes heat.
Radiation is not itself hot or cold. It varies by wavelength and frequency.
Roger C.
Regarding temperature & energy balance … since there is no net work being done on the earth or by the earth, then ΔU = δQ
* δQ = solar energy in – thermal IR out (+tiny bits of geothermal energy flow that can safely be ignored)
* ΔU = mc ΔT (summed over the various parts of the earth & atmosphere; plus a few other minor contributions that can be safely ignored).
So it is a string of logic:
(ΔT = 0) (ΔU = 0) (δQ = 0)
Anyone of these implies the others for the earth. I was saying that since we know experimentally that the temperature is not changing, then we know ΔU = 0 and δQ = 0
“If it hits matter then it heats matter [yes], it becomes heat [no].”
This is a subtle point. “Heat” = “Q” = “the variable in the first law” is a movement of energy due to a temperature difference; an object cannot “contain heat” or “have heat”. So yes, thermal IR is heat, just like collisions of the atoms of hot and cold objects are “heat”.
“Radiation is not itself hot or cold.”
Only in the sense that an individual atom is not hot or cold; only sets of atoms have a temperature. The temperature of set of atoms is a measure of the average energy of all the atoms. The temperature of thermal radiation is a measure of the average energy of the photons.
* the set of photons from the sun IS 5780 K in a very real sense.
* the set of photons from my body IS 310 K in a very real sense.
* the set of photons from the cosmic microwave background IS 2.7 K in a very real sense.
“ΔU = δQ – δW does not contain time term (t) in it.”
That is hardly even worth a reply. Any equation can be divided by Δt on both sides.
I forget that angle brackets get dropped from posts (they are interpreted as html). The line in the previous post should have looked more like
(ΔT = 0) ↔ (ΔU = 0) ↔ (δQ = 0)
where I had tried to make double-headed arrows with the angle brackets. Each one is true for the earth if and only if the others are true (again, ignoring tiny contributions like geothermal energy or thermal energy from burning fossil fuels).
[mod: you have to use an escape sequence, without spaces… & l t ; & g t ;
Like this < >
Or much more difficult tex –Tim]
TB says: Max: It doesn’t work like that…etc.
Roger, that’s a good succinct summary of the whole farrago.
TB: Says I think we are ready for the summary post David keeps promising.
This weekend, this weekend… 🙂
Timsays
“Any equation can be divided by Δt on both sides.”
Only on paper not in reality. Introducing t and m2
means you are averaging over time and area over the horizontal surface . At any time the earth is only lit on one hemisphere but radiates from the whole sphere.
When lit input is greater than output, when not lit, output is greater than input. Effective power and resulting temperature varies horizontally over time during rotation .There is no equilibrium so the 1st law of thermodynamics cannot be used.
The 1st law can only be applied vertically. The temperature profile is stable
As air rises KE changes to PE according to
m g h = m c T ( conservation of energy)
m = mass
g = gravity constant
h = height above surface
c = specific heat constant
T = temperature
cancel m and rearrange
T/h ( lapse rate ) = g/c
Which is what we observe
Roger C says: ““There is no equilibrium so the 1st law of thermodynamics cannot be used.”
Are you *sure* you want to say that Conservation of Energy only applies to systems in equilibrium? Most people consider it to be one of the fundamental, universal pillars of modern science.
————————————————
TIM: “Any equation can be divided by Δt on both sides.”
ROGER C: “Only on paper not in reality. “
Now you seem to only accept Joules, but not Watts, as “reality”. If δQ = 1000 J of solar energy get absorbed by 1 m^2 in Δt =one second, there is no problem at all saying that δQ/Δt = 1000 W of solar energy get absorbed by 1 m^2.
————————————————
Your “derivation” of the lapse rate is a start, but it is a little incomplete. For instance, the heat capacity in T/h = g/c is cp = heat capacity at constant pressure. But clearly the air is not at constant pressure as it moves upward so m cp ΔT is not the change in energy. A little more sophistication is needed.
See wikipedia for a better derivation: http://en.wikipedia.org/wiki/Lapse_rate#Dry_adiabatic_lapse_rate
Tim Folkerts says
“So yes, thermal IR is heat”
This is completely wrong.
This means according to Tim’s definition that radiation from a colder object being absorbed by a warmer object is heat.
So a colder object according to Tim will heat the warmer.
This is a common distortion of the heat definition that is quite common with advocates of IPCC science and the greenhouse effect.
Not one physics textbook on the planet agrees with Tim.
Physics departments all over the world agree with Clausius that heat can only flow spontaneously from a higher to a lower temperature.
“Max: It doesn’t work like that. The system accumulates energy in the various components commensurate with their heat capacities, emissivities and the energy throughput in a dynamic system. They then express that energy level as a temperature, and they radiate in proportion to that temperature. The radiation doesn’t do much below the point where it can emit directly to space, because it cancels out by and large. But that doesn’t change the fact that things radiate in proportion to their temperature and emissivity, whatever else is going on in the way of other processes.” ~tb
The temperatures given are usually for black body radiation as decided by a Planck curve for a given temperature, and it goes as T⁴. Not sure if I’ve said that I’ve been studying math and physics with brief interruptions for various other subjects and skills for most of the last 25 or 26 years now, but I’ve actually been studying math and physics since I was about 6 and discovered to my dismay that there was something huge missing which wasn’t just a case of the encyclopedias in the hallway being 1963 Brittanicas.
With anything else, if you look, you can generally find one explanation and understand a single general mechanism or body of phenomena to capture it. One set of mathematical equations, one set of theoretical structures, everything was all nice and neat in this way… but when I tried to figure out just what the hell “everything” actually was I found two!?!
“Oh dear, perhaps that fellow Feynman was able to make some progress, oh, and I wonder what became of that ‘quark’ idea I read about somewhere?”
I later came to idolize Feynman for many things, and actually got to see clips of his role in the Challenger hearings, which was kind of a big thing for me, being almost 6 years old and having seen every previous shuttle launch I could catch on tv up to that point, my mom said my eyes just kinda filled up and I sat there trying to understand how something like that could have happened… I used to tell people I was going to be a rocket scientist because I figured that was the smartest job there was… after seeing Feynman’s “when I put this O-ring into ice water it no longer returned to it’s original shape, …there’s your problem” answer to Congress and reading most of Six Easy Pieces and Six Not So Easy Pieces I learned that while there wasn’t yet a single answer to how things work, there was a smarter job than rocket scientist… theoretical physicist/bongo drummer!
…long story… uh, long, this isn’t a matter of my misunderstanding the way matter and electromagnetic waves interact.
Certain molecules are composed of atoms with different masses and some of those produce interesting responses to changes in energy levels.
Molecules with two atoms linked to a different atom tend to make physicists happy because of all the cases where you might hear “assume the system is composed of linked masses and springs such that the spring coefficient is…” and have it actually be an excellent description of the interesting properties of said system.
C=O=C
O
–\
–H
–/
O
The catch is, those interesting vibrations have certain differences induced by harmonics, electron interactions, rotational modes, and toss some quantum mechanics in there for flavor.
___________________
A molecule needs to have a dipole moment for a vibrational mode to be IR active, i.e. the electron clouds need to be permanently or temporarily distributed such that there are positive and negative portions. Those modes can be excited by and result in emission of IR wavelength photons.
When there is an overlap between vibrational and rotational states there are additional groups of lines that show up in the spectra, uh, I think the names were J, P, and Q? Been years to be honest.
Either way, when you talk about CO2 and H2O taking part in IR absorption/emission, at no point should it ever be treated as though this is some sort of constant and ongoing process. It is specifically the opposite for CO2 in fact, only vibrational modes produce a dipole for CO2, so the idea that all CO2 molecules are always vibrating in the correct modes to absorb and emit IR is obviously ridiculous. CO2 molecules in randomly distributed states have a smaller portion of the phase space which is IR active, hence the two main spikes at 4~ and 15 microns.
H2O and CH4 have permanent dipoles and various vibrational modes which are IR active, these molecules can absorb and emit IR across a wider portion of the phase space of states you may find them in, hence the broad spectra full of lines for said molecules.
For materials such as liquid water it is more complicated given the way the hydrogen bonds interact, and indeed the hydrogen bonds can be distorted enough to store energy which isn’t available kinetically, thus the unusually high heat capacity and conductivity of water.
For soils and sand and rock the internal energy will be the vast majority of the total energy of the system, with vibrational energy being a minor component, unlike gases. The total kinetic energy still has a phase space with vibrational modes and there are modes which will result in thermal emission of IR.
Which goes to what Tim said: “x_rad = energy received as radiation by the earth = (shortwave radiation from the sun) + (longwave radiation from the atmosphere) is indeed larger than the y_rad = energy lost by the surface.”
Here you are treating the emissions by the surface and the emissions by the atmosphere separately right?
Radiative emission is usually given as: P = εσA(T⁴) which seems fine at first.
Unfortunately that equation is only valid for emissions into an ambient environment which is much cooler than the hot surface.
For the situation like the surface and atmosphere, the temperatures are far far too close to use that approximation, it should be P = εσA(Th⁴ – Tc⁴) actually.
Similarly the idea that radiation is the only way in which vibrational kinetic energy can be transported along a temperature gradient ignores sensible heat transfer.
It should be Ptot = Prad + Psh = εσA(Th⁴ – Tc⁴) + kA((Th – Tc)/d), with convection being a modification of the distance over which conductive losses are calculated by stripping away the warmed layers and transporting that energy upwards.
Adding evaporation is complicated given the transfer of latent heat that is later released by condensation, but the overall concept doesn’t change too much.
___________________
Summing it up, vibrational modes make up most of the internal energy in gases, and a much smaller fraction of the internal energy in liquids and solids.
Temperature is a measurement of kinetic energy which is translational, rotational, and vibrational. For solids the translational modes can be ignored, as can rotational modes in most cases, so vibrational modes account for essentially all of what we measure as the temperature of a solid object, right?
With a liquid and gas the vibrational modes are far larger portions of the total internal energy, but a measurement of temperature in those mediums includes the energy of the translational and rotational modes.
…
Radiation in the IR spectrum can be caused by and result in molecular vibrations, and if that was the only way vibrating molecules could transfer energy it would be accurate to attribute all power lost by those molecules to radiation, perhaps.
I’m pretty sure the transfer of energy from a solid to a gas doesn’t involve large amounts of translational and rotational energy, so that must mean molecular vibrations are responsible for direct physical transfer of heat through conduction… and radiative transfer of heat through emission.
If that is the case, and I’m confident it is for numerous reasons… then the same fund of kinetic energy has to be distributed among the various forms of heat transfer from a surface, so the idea that bodies behave as though they are emitting into a vacuum at all times is incorrect.
…
Accordingly that means one of two things are true:
1. A body emitting radiation into a vacuum has a temperature, and thus an emission temperature corresponding to the total kinetic energy present in the molecular vibrations.
or
2. A body emitting radiation into a vacuum has a temperature, and thus an emission temperature corresponding to the total kinetic energy present in the molecular vibrations and a special fund of vibrational energy which only appears if you place the body into an atmosphere.
Thanks Max, an interesting comment, which could become a whole series of posts in their own right. I think the engineers key to this is heat capacity. If the energy is hiding in there, it will be discoverable via the ability of the mass to transfer heat to its surroundings. Conversely, by supplying a known amount of energy to a mass, we can use several methods to measure its increase in temperature and find out if any of the energy vanishes into modes we’re not measuring. As well as Kinetic and Potential energy, there is also chemical energy.
Took a while to put everything together, had to go and check and make sure that I was not in fact mistaken about this, as it seemed so obvious to others that I was wrong, but I couldn’t figure out exactly how to explain what they were/weren’t seeing.
Then it hit me, the vibrational energy of molecules in a solid is responsible for infrared emission AND conduction to the gas molecules in contact with the surface.
So a surface which is emitting radiation at full power has all the vibrational states available taking part in IR emissions/absorption for a surface at that temperature.
Adding an atmosphere which conducts/convects energy from the surface also requires energy from those vibrational states.
So either temperature measurements of solids include more than the vibrational kinetic energy, or a surface at a given temperature can not emit radiation at full power while also undergoing conductive and convective transfers to the atmosphere above it.
Bryan says: “This means according to Tim’s definition that radiation from a colder object being absorbed by a warmer object is heat.
So a colder object according to Tim will heat the warmer.”
Ah .. you are so close, but you have misunderstood what I said and misunderstood “heat”. I should write an article so that I can refer to it each time I run into this misunderstanding. But here is the brief answer.
In thermodynamics, “heat” = “Q” as used in the first and second laws is the net transfer of energy due to a temperature. In any thermal interaction, there will energy moving from hot to cold and from cold hot hot. For example, when a warm object is placed in contact with a cooler object, there will be zillions of collisions each second involving individual atoms. It will be more common for the atoms of the warm object to transfer energy to the atoms of the cool object, but some of the collisions will transfer energy the other way — an atom in the cool object that just happens to have a larger than average energy will hit an atom in the warm object that just happens to have a smaller than average energy. This is perfectly allowed by the 2nd Law. The only requirement is that the NET transfer is always from warm to cool (or entropy would decrease).
Similarly, there is nothing to stop photons from traveling from cool regions (like the atmosphere) to warmer regions (like the ground). The only requirement is that there are MORE from warm to cool than from cool to warm, so that the NET transfer is always from warm to cool (or entropy would decrease).
So the colder will transfer SOME energy to the warmer object, but the “heat” = net transfer is still from warm to cool.
————————————————————————————————
EVERY WELL-WRITTEN physics textbook on the planet agrees with me.
Physics departments all over the world agree with ME that heat can only flow spontaneously from a higher to a lower temperature (as this post and my previous post both claim).
If you REALLY want to understand this, read up on the modern, statistical mechanical approach to thermodynamics, entropy, and the 2nd Law.
Tim F: “there is nothing to stop photons from traveling from cool regions (like the atmosphere) to warmer regions (like the ground).”
Apart from the gazillions of intervening molecules, many of which are heading upwards in convection processes. Of those which do reach the surface, 70% will be absorbed within a few microns of the ocean surface. As I wrote in an article lest year; Yes Virginia, back radiation transfers energy to the ground, just not very much. Certainly not enough to account for the 91K difference between the average temperature of the Earth’s surface and that of the moon. Nor enough to account for 33K. It’s a rubbish theory, destined for the scrapheap.
Tallbloke, those gazillion molecules are completely a side issue (and convection is a side issue of a side issue), independent of the fundamental question about the possibility of a photon moving from a cold region to a warm region.
After that tangent, you actually seem to agree with me and the rest of the physics world (and therefore disagree with Bryan) that photons do indeed move from the atmosphere to the ground, so we are only concerned about the MAGNITUDE of that IR. Measurements suggest a value of about 330 W/m^2 for those downward IR photons (or a net upward flux of ~ 60 W/m^2 of IR photons). That is a LOT of energy! Or do you have experimental measurements that contradict the 330 W/m^2 figure?
IR active gases are enough to change the temperature by ~ 30 K. Throw in the slower rotation of the moon and it is easy to explain the differences between earth and moon, too. We aren’t going to resolve that here and now, but only a small handful of people have difficulty understanding how GHGs and rotation account for differences in temperatures.
It is possible to question the impact of FURTHER CO2 on the future temperature, but it is pretty futile to think that there is no significant warming from IR gases. There has now been a decade or two of active challenges to the basic greenhouse theory — and none have been successful at gaining support. Theories that withstand active challenge are rarely destined for the scrapheap!
Most of the discussions and the scientific conflicts in this thread are due to the fact that two-way heat propagation formulation is used. It is a sound algoritm to calculate temperature distributions. But it gives rise to spurious absorption in the atmosphere which is compensated by back-radiation of heat. As long as one considers the back-radiation of heat as an auxiliary variable, there is no problem. But do not try to give a physical interpretation to the spurious absorption and the back-radiation to compensate for it.
I have made a model where I use one-way heat propagation formulation by radiation, and I get K&T type of global budgets which are solving the majority of the problems which have been raised in this thread. You find that diagram as fig 16 on page 22.
Click to access IR-absorption_updated.pdf
The paper starts with two simple problems.
The one-slab model of a semi-transparent atmosphere.
Next a stack of completely opaque slabs.
Very simple algebra, to compare the one-way and the two-way formulation of heat propagation.
Unfortunately, the maths for a multi-layer semi-transparent stack is more complicated. But it is only a generalization of the earlier two simple examples.
The resulting equation (14) is depicted in fig 4 as an example.
The model tells that the convection is predominant for the evacuation of heat from the surface to higher layers where IR-sensitive molecules with more than 2 atoms take care of radiation of the heat of which the planet receives from the sun back into outer space.
[Reply] The first line of your document sets up a straw man argument. Energy is not heat. Heat is not energy. No-one talks about “back radiated heat”.
Tim,as has been explained to you many times, nearly all that 330W/m^2 flux measured near the ground comes from near the ground, not high up in the sky. It is just the expression of the temperature of the near surface air, not a huge energy source. Prevost exchange doesn’t warm anything. Especially not the ocean, 70% of the surface.
Tim Folkerts this is what you said without qualification.
“So yes, thermal IR is heat”
This was in response to a post by Roger Clague who said correctly radiation is not heat.
I said Tim this is completely wrong, pointing out why Roger is right.
You now agree with me but pretend that you did not make an error.
In a purely radiative exchange between two objects at different temperatures heat is the difference between the two radiative fluxes.
As Tallbloke and JWR point out the Prevost Exchange Energy does not heat anything.
Now instead of thanking me for pointing out your mistake you sneeringly advise me to “If you REALLY want to understand this, read up on the modern, statistical mechanical approach to thermodynamics, entropy, and the 2nd Law.”
You fool no-one but yourself by such behaviour.
Its quite clear that I have a firmer grasp of what the second law is all about than yourself.
Tim.
P = εσA(Th⁴) is what you use for a surface radiating into a vacuum, and it is also what you can use for a surface radiating into an ambient environment at least three times cooler than it is.
P = εσA(Th⁴ – Tc⁴) is what you use for a surface radiating into an ambient environment of a similar but cooler temperature, like the ground radiating into the atmosphere.
In case you can’t tell, that Th⁴ would be the 396 W/m^2 from the ground, and the Tc⁴ would be the 333 W/m^2 from atmosphere, so the actual figure you should have been using all this time is 63 W/m^2 from the ground, because that is what back radiation actually does.
Oh, note of course that those values are assuming the ground temperature includes a fund of vibrational energy dedicated for IR emission only, as well as an extra fund of vibrational energy for conduction/convection that for some reason does not change the ground temperature… must be sneaky ninja vibrations, right?
Tim Folkerts you say
“After that tangent, you actually seem to agree with me and the rest of the physics world (and therefore disagree with Bryan) that photons do indeed move from the atmosphere to the ground”
Where have I ever said that photons do not move from the atmosphere to the ground?
Are you incapable of reading or do you just invent random opinions for others?
In block capitals for the hard of reading.
PHOTONS MOVE FROM THE COLDER ATMOSPHERE TO THE WARMER GROUND AND MOST ARE ABSORBED.
“[Reply] ( to JWR )The first line of your document sets up a straw man argument. Energy is not heat. Heat is not energy.”
I disagree. Heat is a form of energy. They both have units of Joules.
I find a lot to support in the paper by Joseph Reynen’s ( JWR ) paper. He is a French dragonslayer and I welcome him to this blog.
Bryan don’t shout at Tim. I find trying to reason with him helps me sharpen my thinking. His comments are deliberately annoying because he is losing the debate. It is good if he changes his mind,
The most important flaws in the radiative theory of atmosphere physics science are
The law of conservation of energy is changed to conservation of power
Radiation is smuggled into thermodynamics
Energy changed to power
Watt/m2 are used by K and T instead of Joules. This is done by adding time and area to the denominator of the equation. This is excused as merely algebra. Adding a new variable to a law of physics is not allowed.
There is no law of conservation of power. All discussion using The K and T diagram is useless.
The concepts radiative forcing and climate sensitivity are also in Watt/m2, and follow from the concept of power budget. They wrongly assume a law of conservation of power. They also don’t work and are useless.
Look at the K an T diagram. You will see
The thermals, latent heat and rain, which do the real work
The absorption , emission and reflection items are irrelevant and used to distract from the real workers and justify including
The CO2 back radiation, which does not exist
Radiation is not part of thermodynamics
Classical and statistical thermodynamics is of particles, atoms and molecules, that obey Newtons Laws of Motion.
Photons do not obey the Laws of Motion.
Roger C: Don’t get me wrong, I think there is much to commend in the paper too. However, experience has taught me that conflating energy and heat just leads to confusion. Energy appears in the forms of kinetic, potential and chemical. Heat is one of the outcomes of energy interacting with matter. You can use the same units to quantify them but that doesn’t mean they are identical. Radiated energy can be emitted by cooler objects and absorbed by warmer objects. Heat (as a bulk property) cannot of itself pass from a cooler body to a hotter body. One of the reasons I banned Doug Cotton from commenting on this blog was for constantly conflating and shape shifting definitions in this area, causing endless useless circular argument and confusion. The other main reason I banned him was his habit of claiming other peoples ideas as his own and refusing to give credit where it is due.
I’m not a dogmatic person and scientific argument can sway my position. However, dragonslayers commenting here should be aware that my tolerance for their modus operandi is at a low ebb.
Roger Clague you say;
“Radiation is not part of thermodynamics
Classical and statistical thermodynamics is of particles, atoms and molecules, that obey Newtons Laws of Motion.
Photons do not obey the Laws of Motion.”
I cannot agree with you here.
Thermodynamics textbooks certainly include radiation.
Radiation is subject to the 4 laws of thermodynamics the zeroth,Ist,2nd and 3rd.
The distinction between flow rate through an atmosphere and energy within an atmosphere is of critical importance.
i) The top of atmosphere energy balance between atmosphere and space is always zero at equilibrium.
At equilibrium the amount of energy entering from space is the same as the amount of energy leaving for space. That represents the flow rate through the atmosphere (my diabatic loop).
ii) The energy exchange between atmosphere and surface is also always zero at equilibrium.
At equilibrium the amount of energy leaving the surface for the atmosphere is the same as the amount of energy leaving the atmosphere for the surface (my adiabatic loop). The amoiunt of energy being exchanged between surface and atmosphere is the energy within the atmosphere.
iii) The balance between KE and PE in the atmosphere is zero at equilibrium.
At equilibrium there will be exactly as much KE in the atmosphere as PE. Thus half of the energy held within the atmosphere will be PE and half will be KE at equilibrium.
iv) PV=nRspecificT at equilibrium.
At equilibrium the value of the product of Pressure and Volume will be the same as the product of the amount of mass (n), the gas constant for that gas (Rspecific which accounts for the differing molecular weights of different gases) and Temperature.
There is nothing in any of that which is dependent on the radiative characteristics of molecules. The whole scenario is limited to the amount of mass, the strength of the gravitational field and the amount of energy entering the atmosphere from outside.
Therefore it must be the case that any disruption in the flow of energy through as a result of any change other than in one or more of those three parameters MUST be exactly countered by a change in the rate of flow elsewhere.
That is an inevitable conclusion from the fact that the Ideal Gas Law is universally valid.
For any other outcome to occur the Ideal Gas Law would be shown to be invalid so the radiative theory of gases must fail on that ground alone.
The only remaining issue is as to HOW the Ideal Gas Law applies in such a way that the effects of changes in the radiative characteristics of molecules are negated and that is the area I have been focusing on for years.
Perhaps we don’t need to directly involve the Ideal Gas Law at all for mere changes in radiative characteristics.
Most of us have decided that GHGs supply an additional radiative window for energy exit to space that is not supplied by non GHGs.
Suppose that that extra radiative window exactly matches the additional absorption capability of the GHG ?
A GHG molecule may therefore absorb upward IR from the ground but it doesn’t send any more energy back to the ground than any non GHG molecule because any energy it carries over and above the energy carried by the non GHGs around it just gets radiated straight out to space or transferred to surrounding molecules to increase the speed of convection.
The Ideal Gas Law would still be operating in the background by setting the vertical temperature profile but that temperature profile is what determines the temperature of ALL molecules at any given height whether they be GHGs or non GHGs.
Therefore the GHGs can get no hotter than the non GHGs around them. The additional radiation they absorb from the ground is simply radiated straight up in an immediate pass the parcel exercise and if it isn’t radiated upward just as quickly then the affected molecules simply rise higher until they are again at the same temperature as all other molecules at the new height.
But what about the observation that outgoing longwave radiation shows a gap in the part of the spectrum where CO2 has absorbed upward longwave from the ground ?
Well, given that the Ideal Gas Law governs the temperature of ALL molecules at a given height what must be happening is that once energy is absorbed by CO2 molecles from upward flowing longwave it is immediately transmitted to all the molecules (including aerosols, and other GHGs) round about which then share out the additional energy and pass it on upwards in an undisturbed flow at their respective wavelengths,
As it happens, for Earth most CO2 is in the troposphere which is awash with water vapour and aerosols of a wide variety of types so it is not difficult for CO2 molecules to pass energy sideways virtually instananeously.
In the event that the redistributed upward flowing energy fails to be radiated upward as fast as it is received from the ground then convection would simply take up the slack by changing speed.
Any failure by the diabatic loop to maintain energy flow through the system is therefore immediately offset by a faster adiabatic loop with no change in energy content for the system as a whole.
At any given moment a multitude of other variables is always creating variations in the upward flux so the volume of the atmosphere is always changing in a negative system response to any forcing element other than more mass, more gravity or more insolation.
During periods that the energy balance is not in equilibrium (all the time) the system will at the same time be changing atmospheric volume so as to move back towards equilibrium and during such periods of transition the relative proportions of KE and PE in the atmosphere must change so as to keep T stable.
The system is a combination or interacting radiative and mechanical processes.
Changes in the radiative characteristics of individual molecules are immediately countered and negated within the system which is why the Ideal Gas Law contains no term for radiation but yet is universally valid.
Bryan, I apologize if I misinterpreted your comments, or attributed others opinions to you. In these long threads it can be tough to remember who said what. And there are plenty of people who refuse to recognize that ANY photons move from the atmosphere to the ground, so I may have been over-reacting to your statements.
OTOH, you did say: “So a colder object according to Tim will heat the warmer.” Here you are attributing things to me that I did not say and do not agree with.
We both seem to be guilty, so lets see if we can say this carefully and agree.
1) Heat = Q is the NET flow of energy from one system to another system due to temperature differences.
2) Thermal radiation is a part of Q: Q = Q(radiation) + Q(conduction) + Q(convection)
3) Photons do move from cooler objects to warmer objects, but there are always more moving from warm to cool, so
Q(radiation) = (photon energy from warm to cool) – (photon energy from cool to warm)
is always positive (as required by the the 2nd Law).
4) There is a net upward flow of thermal IR photons from the earth’s surface.
5) The net upward flow would be larger if there were no GHGs in the atmosphere, so the surface would cool if GHGs were removed.
6) It is legitimate to say “GHG’s slow the cooling of the surface”. It is a matter of semantics whether or not it is legitimate to say “GHG’s warm the surface.” It is WRONG to say “GHGs result in a positive Q to the surface (ie that GHGs ‘heat’ the surface)”.
If you disagree with any of this, let me know and we can iron things out.
On hurdle in these sorts of discussion is that colloquially, “heat” is used many different ways. Even scientists will (depending on the context) use “heat” in different ways, so it is important to recognize the context when discussing thermodynamically topics.
Tallbloke says: “Tim,as has been explained to you many times, nearly all that 330W/m^2 flux measured near the ground comes from near the ground, not high up in the sky. ”
Yes, this is true. But I don’t why you are making this point. We both agree that 330 W/m^2 comes from the atmosphere to the ground. Where in the atmosphere it comes from is not impoartant in terms of simply balancing energy flows.q
Tallbloke
Heat is kinetic energy. That is heat is a form of energy, heat is energy.
Bryan says
“Thermodynamics textbooks certainly include radiation. Radiation is subject to the 4 laws of thermodynamics the zeroth,Ist,2nd and 3rd.”
Thermodynamics books include radiation because when it hits matter it becomes heat
My Google search found this
“Radiation of photons or photon-like particles such as neutrinos is not in the purview of classical thermodynamics”
http://www.tu-chemnitz.de/physik/CPHYS/Con/jetc11/radiation
Can you give me a reference for a description and discussion of radiation thermodynamics?
Did you intend to post this here or in your own thread?
“ii) The energy exchange between atmosphere and surface is also always zero at equilibrium.
At equilibrium the amount of energy leaving the surface for the atmosphere is the same as the amount of energy leaving the atmosphere for the surface (my adiabatic loop).”
I disagree. Or are you excluding the energy in the ‘diabatic’ loop from this?
If the KE in an atmosphere rises (too hot) so that more energy is leaving for space than is coming in then the atmosphere will expand and in doing so convert KE to PE, reducing the outflow (cooling) to match the inflow again and thereby regain thermal balance.
If the KE in an atmosphere falls (too cold) so that more energy is coming in from space than is going out then the atmosphere will contract and in doing so convert PE to KE, increasing the outflow (warming) to match the inflow again and thereby regain thermal balance.
It is the switching between KE and PE that provides the mechanism whereby the Ideal Gas Law ensures radiative balance at the top of the atmosphere by varying atmospheric Volume (V) as necessary to maintain a stable temperature (T).
Such corrective processes deal with any forcing element other than more mass, more gravity or more total energy entering the system. If any of those three elements change then both V and T must rise.
If anything else varies only V changes so as to return to the initial T.
Stephen Wilde says
“the Ideal Gas Law contains no term for radiation but yet is universally valid.”
The term for radiation may not be explicit but it is implicit
One formula for the Universal Gas Constant makes this clear
R = Cp – Cv
where cp is the specific heat for a constant pressure and cv is the specific heat for a constant volume for a particular gas.
Cp for CO2 varies by 13% between 250K and 350K whereas Cp for Nitrogen is almost constant.
This indicates the increased radiative activity of CO2 between these temperatures.
If we took an IR transparent box of each gas at STP to outer space the CO2 would cool much quicker due to radiative loss.
What is true is that for neighbouring volumes of gas in the atmosphere the radiative effects of each volume would self cancel with its neighbours.
Only at the TOA will there be a significant unbalanced radiative loss.
tallbloke said:
“I disagree. Or are you excluding the energy in the ‘diabatic’ loop from this?”
Yes, I am keeping the two loops separate because that is how one shoud deal with the throughput and energy content as independent phenomena.
I did intend to put it here because my comments follow through on things said here by other contributors.
[Reply] Thanks for the clarification, and no worries, just checking you hadn’t posted to the wrong thread and interrupted your own flow.
Bryan said.
“Only at the TOA will there be a significant unbalanced radiative loss.”
Which is why one needs a change in atmospheric volume and a change in the speed of circulation to act as a negative feedback.
See my post at 4.06 to see how the system could self correct.
Dang … I posted that last one before I was ready. Oh well. Here is some of the rest of that thought …
Tallbloke also says “Prevost exchange doesn’t warm anything.
As an aside, Googling “Prevost exchange energy” (with the quotation marks) gives me only 415 results, nearly all of which are from skeptical blogs about climate. Prevost didn’t even know this energy was electromagnetic radiation.
According to wikipedia “Prevost’s theory of exchanges stated that each body radiates to, and receives radiation from, other bodies.” In other words, this it simply the exchange of thermal photons in today’s language. So sunlight is “Prevost exchange energy” from the sun to the earth, which CERTAINLY warms things.
(If you have some other definition of “Prevost exchange energy” that you would like to share, please let us know.)
Bryan sais:
“The term for radiation may not be explicit but it is implicit”
If it is implicit then that is because it doesn’t need to be explicit i.e the other explicit terms deal with the radiative effects between themselves which is my point isn’t it ?
As long as the explicit terms are kept in balance the radiative characteristics do not matter which is why only mass, gravity and insolation have an effect on T.
It appears that V takes the strain by varying KE relative to PE.
Roger Clague says:
“Can you give me a reference for a description and discussion of radiation thermodynamics?”
Certainly!
Any University Level Physics Textbook which has a Thermodynamics section.
I particularly recommend
Heat and Thermodynamics by Zemansky.
However here is a typical PDF copy on the topic
Click to access BlackBodyThermo.pdf
Tim F:
“Prevost exchange energy” from the sun to the earth, which CERTAINLY warms things.
It’s not being exchanged. The clue is in the phrase. Exchange energy is just what it says it is.
By the way, Prevost doesn’t show up much on the web because modems were so slow in the C18th. 😉
“We both agree that 330 W/m^2 comes from the atmosphere to the ground. Where in the atmosphere it comes from is not impoartant in terms of simply balancing energy flows”
It is important in terms of AGW theory about the power of additional co2 to increase surface temperature though. More rapid convection will simply negate it. Stephen’s expansion of the atmosphere will negate it too.
Stephen 3:33pm and 4:06pm: “..varying atmospheric Volume (V) as necessary to maintain a stable temperature (T). Such corrective processes deal with any forcing element other than more mass, more gravity or more total energy entering the system. If any of those three elements change then both V and T must rise. If anything else varies only V changes so as to return to the initial T.”
Yet mass, gravity, insolation are stable where Tlocal and global Tavg. vary over any time frame chosen thereby proving V then doesn’t compensate over the time frame chosen. How do you explain that there is no stable earth system temperature (T) actually observed/measured/felt?
Trick asked :
“How do you explain that there is no stable earth system temperature (T) actually observed/measured/felt?”
Multiple forcing elements changing constantly and interacting on all timescales.
Especially sun and oceans which each vary on multiple timescales.
Roger Clague says: January 19, 2013 at 4:05 pm : “Heat is kinetic energy. That is heat is a form of energy, heat is energy.”
“Heat” = Q is a process that transfers energy, much like “work” = W is a process. You can “do work” on an object to change its macroscopic KE, and you can “do heat” on an object and change its microscopic KE. But an object cannot “have work” or “have heat”.
As I said recently, the word “heat” is “officially” used in thermodynamics to mean Q (energy transfer between two objects), but also used “unofficially” to mean U (internal thermal energy of a single object, like you are doing), and even T (temperature, is in “boy, the heat is bad today”). In discussions of thermodynamics, it is critical to clearly distinguish which meaning is intended!
[Reply] I think you mean ‘*net* energy transfer between objects’?
Stephen writes only forcings are mass, insolation, gravity which are stable. So there are other mutiple forcings elements now causing T to vary! Stephen now adds oceans not in the 3:33 and 4:06 summary at least.
Now have mass, insolation, gravity and oceans. 1st three are stable, oceans must then not be stable.
What other multiple T forcing elements exist that must not affect V b/c V doesn’t compensate allowing T to vary?
Trick,
Multiple forcings other than mass gravity and insolation simply upset the thermal balance temporarily but in practice the system is never at equilibrium so one cannot ever actually observe measure or feel the T set by mass, gravity and insolation.
All the time the volume of the atmosphere and the speed of the adiabatic loop are in constant flux as a negative system response with variability in T observable in every location from the bottom of the oceans to the top of the atmosphere.
The system response is lagged hence short term top of atmosphere energy imbalances but in the end T averaged over time stays stable.
I know you are too bright to need to raise such naive questions so why do it
Tim Folkerts says:
“Prevost didn’t even know this energy was electromagnetic radiation. ”
True, but insnt it remarkable how clear thinking these giants of thermodynamics like Prevost and Carnot were.
To point out the correct direction even when the accepted theory and language was misguided.
Actually Prevost’s theory is more helpful to the two way photon exchange approach than the one way Poynting Vector approach of JWR
Two objects at the same temperature radiating and absorbing radiation from one another will not ‘heat’ each other up.
However if one is at a higher temperature it will radiate more intensively than the cold.
The higher temperature one will lose internal energy and the lower temperature one gain internal energy.
Thats what we call heat transfer!
Tim says,
“the word “heat” is “officially” used in thermodynamics to mean Q (energy transfer between two objects), but also used “unofficially” to mean U (internal thermal energy of a single object, like you are doing)”
Yes, you are right.
Heat is thermal energy in the process of transfer. Heat is a verb not a noun. When I heat an object I increase its thermal energy. An object has thermal energy it does ‘have’ heat.
The word heat has historical association with the incorrect ‘calorific’ theory. I do not need to use it.
“An object has thermal energy it does ‘have’ heat.”
But an object can have the property of being hot, or hotter than another body.
http://www.ifpaenergyconference.com/Thermal-Energy.html
“From a physics standpoint, thermal energy for an object is calculated by summing the sensible and latent forms of internal energy within an object. Every object on the planet has what is known as internal energy. Internal energy is the sum of all forms of energy within an object. Every object has the following potential properties of internal energy: sensible energy, latent energy, chemical energy, nuclear energy. Sensible energy refers to the portion of energy of an object that is associated with kinetic energy, whereas latent energy refers to the phase of matter of the object such as solid, liquid, or gas. Thus, thermal energy refers to the combination of sensible and latent energies within an object.”
It should be noted that the latent energy isn’t going to show up in the objects temperature, because objects stay at a constant temperature while gathering sufficient energy to change state.
Stephen 4:57pm – Good response actually. Naïve questions sometimes work. For a bit there, seemed you were implying planetary atm. V was important compensation to keep Tlocal, global near surface Tavg. fixed in the face of forcing variability, oceans, atm. composition changes, your diabatic and adiabatic cycle changes, et. al.
The oldest book on Earth Science my library syndicate could find for me was from 1999. The index does not ref. the word “volume” at all. Chapter 3 on Global Energy Balance starts “Earth is heated by visible radiation from the sun and cools by radiating infrared energy back to space. Earth’s surface temperature depends on the amount of incident sun light, the planet’s reflectivity and the (emissivity) of its atm. …. As we saw in in Chapt. 1 a planet’s atm. allows sunlight to come in but slows the rate at which heat is lost.”
Interesting basic physics science – only 14 yrs. old though. I did not in any way sort out the text, it was simply the oldest © relevant text listed.
I have other ways to browse papers from the 60’s, may spend time on that to see if mass, insolation, gravity, oceans, volume were on topic for the global near surface Tavg. trend setters back then instead of radiation/albedo/atm. emissivity.
Nearest old papers from 60s and 70s I did find & read were on the planetary probes using radio transmitter signal occultation to compute atm. density (it is NOT easy) as a function of altitude and they used P=density*R*T & lapse -g/Cp w/o resorting to est. of planetary atm. volume to compute T profiles.
Strange that Potential Energy isn’t in that list.
It is a type of internal energy in non sensible form after all.
It is latent energy but not related to a phase change. Rather it is related to the position within a gravitational field.
Perhaps this whole kerfuffle is a result of a failure to appreciate the practical utility of Potential Energy as a temperature regulator.
PE is the true global thermostat.
The quantity of PE within an atmosphere regulates the balance between energy in and energy out at the top of the atmosphere.
When Willis Eschenbach refers to equatorial convection as the global thermostat he is really just describing a portion of the global convective mechanism whereby the vigour of convective uplift alters the balance of PE and KE to maintain thermal equilibrium.
Every change one can imagine arising from non radiative processes just boils down to the KE / PE balance.
The phase changes of water just make it easier by increasing the effectiveness of a given amount of convective uplift.
The ozone warming in the stratosphere makes it harder by decreasing the effectiveness of a given amount of convective uplift.
Solar induced composition changes in the atmosphere above the stratopause either help or hinder the effectiveness of a given amount of uplift.
But in the end the stability of the entire system depends on shifting the right amount of energy from KE to PE or back again so as to match the kinetic energy content (T) of an atmosphere with that required for outgoing radiation to match incoming radiation.
Climate change is just variation around the mean as the system takes time to apply the negative system response to any forcing element other than mass. gravity and insolation.
Is anything more to be said ?
Tim Folkerts says
“6) It is legitimate to say “GHG’s slow the cooling of the surface”. It is a matter of semantics whether or not it is legitimate to say “GHG’s warm the surface.” It is WRONG to say “GHGs result in a positive Q to the surface (ie that GHGs ‘heat’ the surface)”.
Firstly’ thanks for your gracious apology.
On warm as opposed to heat.
Heat has a definite meaning in thermodynamics, warm does not have this status and is ambiguous and for this reason is best avoided.
If the higher temperature surface has no continuing power supply then the colder object will not increase its temperature.
If the higher temperature object has a continuing power source (internal or external) then placing a colder object instead of an even colder one(deep space) will cause the surface temperature to increase.
So reduce the heat loss is always true whereas warm the surface is sometimes true and fundamentally depends on the reaction of the higher temperature surface
Apologies to Bryan since I didn’t give enough thought to his post at 4.12 pm where he pointed out that:
“The term for radiation may not be explicit but it is implicit
One formula for the Universal Gas Constant makes this clear
R = Cp – Cv
where cp is the specific heat for a constant pressure and cv is the specific heat for a constant volume for a particular gas.
Cp for CO2 varies by 13% between 250K and 350K whereas Cp for Nitrogen is almost constant.
This indicates the increased radiative activity of CO2 between these temperatures.”
Which means that contrary to my earlier assumption radiative characteristics would change the value of Rspecific at ambient temperatures.
It would be interesting to know whether such a change would raise or lower the value of Rspecific.
Either way that need not alter my basic proposition because the change in the value of Rspecific whether up or down would not be accompanied by more total energy (PE+KE) within the atmosphere because there would be no increase in mass, gravity or insolation.
In the absence of an increase in total energy content the change in Rspecific could only affect V and not T as well.
The atmosphere would simply adjust in the way described in my post at 4.06 pm depending on whether the change in Rspecific resulted in too little KE or too much to balance incoming energy.
Tallbloke says “It’s not being exchanged. The clue is in the phrase. Exchange energy is just what it says it is.”
I’m confused. Are you saying that there are no thermal IR photons going from earth to the sun so there is no “exchange”? So if I went 150,000,000 km from earth and pointed an IR camera at earth, there would be no photons to detect?
Please define (preferably with an equation) precisely how you would calculate the “Prevost exchange energy”.
“By the way, Prevost doesn’t show up much on the web because modems were so slow in the C18th. 😉 “
Modems were even SLOWER in the C17th, but Isaac Newton shows up A LOT on the web! 😉
Tim F: Obtuseness is your true strength. Exchange leaves a remainder in unequal exchanges. This is net radiation in this case. Don’t tell me the earth heats the sun with photons even though it might absorb them (or blast them back at Earth with the solar wind). 😉
Just seeking clarity through some rhetorical questions, Tallbloke. And it seem that you are unwilling to define the terms you are using, so seeking clarity is a challenge.
And I won’t tell you that the earth “heats” the sun because we have already established that “heat” means a net flow of energy, and clearly the net flow of energy is the other way. But the earth’s photons do (to some tiny degree) make the sun warmer. Are you saying the sun can absorb those IR photons, but that their energy “disappears” without *any* effect on the sun?
I would say the exchange is very one-sided (on the order of 10^-9 times less power per meter of earthlight falling on the sun than sunlight falling on the earth if my rough estimates are correct) but that is not zero. The point is that “one-sided provost exchange energy” between objects of vastly different temperature very effectively heats the cool object. “Balanced provost exchange energy” between objects of at the same temperature cuts the heat to zero. Anything in between these two extremes is also possible.
[Reply] “But the earth’s photons do (to some tiny degree) make the sun warmer.” No they don’t. They make the Sun cool to space a tiny bit slower.
Bryan says January 19, 2013 at 8:07 pm
“So ‘reduce the heat loss’ is always true whereas ‘warm the surface’ is sometimes true and fundamentally depends on the reaction of the higher temperature surface”
Bryan, it looks like we are rapidly converging the same position (which is, of course, the correct one 😉 ). Or perhaps more precisely, we are expressing our positions in ways that are clear to each other.
And for the earth in particular, there IS always an input of energy from a higher temperature surface (the sun), so the conclusion is that the radiation from the GHGs serves BOTH to ‘reduce the heat loss’ AND to ‘warm the surface’. Which is, in a nutshell, “the greenhouse effect”. 🙂
[Reply] “AND to ‘warm the surface’” Don’t think so. Colder things don’t warm warmer things, as the 2nd law states.
Stephen ponders: “It would be interesting to know whether such a change would raise or lower the value of Rspecific.
It turns out that Cv for CO2 ALSO changes as you change temperature. So the difference Cp – Cv = R remains constant.
The problem with the account of Tim and Bryan is that they propose that the effect of GHGs, by reducing the rate of heat loss, both warms the surface AND expands the atmosphere.
Assuming that the net effect really is warming one has to change both sides of the Ideal Gas Law equation so raising T must also raise V to maintain equilibrium at top of atmosphere.
But then there is a drop in average density which has a cooling effect so how does the radIative theory deal with that in the absence of any additional energy being supplied from outside the atmosphere ?
Likewise if the net effect were to be cooling then reducing T also must reduce V which gives an average rise in density for a warming effect.
How does radiative theory take account of the contrasting thermal effect of the reduction or increase in density ?
I think they say that the troposphere warms and expands whilst the stratosphere cools and contracts so that the total volume of the atmosphere stays the same so one can have a rise in T with no rise in V.
But then the Ideal Gas Law is out of balance because T has changed on one side yet PV stays the same on the other side.
There would be a permanent energy imbalance at top of atmosphere but that cannot happen.
Whatever goes on within an atmosphere one cannot have more energy going out than coming in or vice versa and there is only equilibrium when the Ideal Gas Law is in balance which it wouldn’t be by the radiative account.
How does radiative theory resolve that ?
My description at 4.06 deals with it.
Stephen 10:08pm: “How does radiative theory take account of the contrasting thermal effect of the reduction or increase in density?…How does radiative theory resolve that ?”
Just switch planetary stuff to P=density*R*T like the planetary probe papers, it works fine with radiative theory b/c it worked for them. As I have written Volume of a planetary atm. is really just defined although you have a concept in your mind for it – can’t be measured very well. It is not easy like a volume of a balloon or the volumes the grand masters used to calibrate their theories, now we use the volumes to calibrate our instruments.
Another way to see it is look at a weather station trace of pressue and temperature – they do not move the same, sometimes against sometimes with each other. Volume weather station is measuring is not defined well though we know PV=nRT. Stick the traces into T & P see how the weather station volume being measured is changing I guess. Who cares, not useful so no one does that.
Trick, surely pressure averaged planetwide is pretty constant. That’s Stephen’s context here.
Tim said:
“So the difference Cp – Cv = R remains constant.”
Thank you Tim.
So I was right in my assumption that radiative characteristics do not change Rspecific.
Which fits with my view that only molecular characteristics that do affect Rspecific can change both V AND T because one needs the change in Rspecific to offset the change in density that results from expansion or contraction so as to obey the Ideal Gas Law.
Now please see if you can deal with my post at 10.08
But I need to expand on that post because I think AGW theory deals with the problem by implying that the average temperature of the entire atmosphere stays the same but that the troposphere alone gets warmer whilst the rest of the atmosphere gets cooler so on average neither T nor V change for the planet as a whole.
But one then has a larger temperature differential between surface and tropopause. The warming troposphere and cooling stratosphere would result in a much higher tropopause which would reduce the density of the troposphere for a cooling effect AND increase the vigour of the convective processes including the water cycle which would both run faster and reach a greater height so as to accelerate upward energy transfer to the higher stratosphere.
The attempt at warming by the GHGs would therefore fail and energy would be transferred upward at the same rate as before.
There must be expansion of V within any layer affected by GHGs (assuming they do have a net warming effect) and that is all that is needed to cancel any radiative effect because the Law applies equally to every layer and not just to the entire atmosphere.
Thus my solution at 4.06 is still the more plausible scenario.
Trick.
The pressure I am considering is average global pressure of 1000 mb or one standard atmosphere.
Pressure changes around that figure represent the ongoing negative system response to any forcing elements other than mass, gravity or insolation. Only those three parameters will change system energy content. Everything else only affects energy distribution.
To deal with more GHGs whilst keeping V and T stable we just get imperceptible changes in the relative sizes, intensities and positions of all the regions above 1000mb and all the regions below 1000mb.
It works well against solar and oceanic forcings so the effects of GHGs are a doddle in comparison.
Weather and climate together are an effective negative system response to any forcing elements but the effect of our emissions counts for nothing against natural variability.
Stephen:” but the effect of our emissions counts for nothing against natural variability.”
I’d rephrase that as “but the effect of our emissions counts for nothing against the planet’s spare capacity for negative feedback”
To save searching time here is a repeat of my post from 4.06:
“If the KE in an atmosphere rises (too hot) so that more energy is leaving for space than is coming in then the atmosphere will expand and in doing so convert KE to PE, reducing the outflow (cooling) to match the inflow again and thereby regain thermal balance.
If the KE in an atmosphere falls (too cold) so that more energy is coming in from space than is going out then the atmosphere will contract and in doing so convert PE to KE, increasing the outflow (warming) to match the inflow again and thereby regain thermal balance.
It is the switching between KE and PE that provides the mechanism whereby the Ideal Gas Law ensures radiative balance at the top of the atmosphere by varying atmospheric Volume (V) as necessary to maintain a stable temperature (T).
Such corrective processes deal with any forcing element other than more mass, more gravity or more total energy entering the system. If any of those three elements change then both V and T must rise.
If anything else varies only V changes so as to return to the initial T.”
Rog.
That alternative is fine by me as long as you realise that any negative feedback does involve a change in the circulation.
The spare capacity for negative feedback via circulation changes must be close to infinite in view of the number of disparat planets with atmospheres, clouds of gas in space, planetary gas giants.and the faint sun paradox which my hypothesis also deals with.
Stephen: And so if the Sun kicks out more, V will increase as more energy is absorbed in the atmosphere, thus lowering density and cooling. Cloud altitude and vapour density must fit into this somewhere. The cloud diminished as the Sun stayed active in the late C20th. Why did the surface warm rather than V increase enough to offset it? Time lag in the system? Ocean oscillation on the up at the same time?
Respectably tallbloke and Stephen, if you put some of those statements into equations I’m afraid you are going to be disappointed. You cannot say that with more solar energy you get warming an increase in columnar volume (true) but since the volume increased the temperature is compensated and remains the same (false).
A decrease in density at a constant pressure at the surface is an increase in temperature, not a cooling. Remember P/ρ = Rs T. You raise temperature the density goes down, has to, which implies larger volume in the column but you have to stop there. T changes, ρ changes. ρ changes, T changes since the pressure is just gravity and mass. That is when you look at a column of air as one single unit.
[Reply] Fair points all.
Tim Folkerts says
“And for the earth in particular, there IS always an input of energy from a higher temperature surface (the sun), so the conclusion is that the radiation from the GHGs serves BOTH to ‘reduce the heat loss’ AND to ‘warm the surface’. Which is, in a nutshell, “the greenhouse effect”.
You need to always keep in mind that radiation is not the only game game in town.
Several other parallel heat transport mechanisms are in play .
For the Sun facing earth side its difficult to detect any warming effect of the so called GHG’s.
At the equator a surface temperature of 120C is theoretically possible but never achieved yet on the Moon this temperature is achieved without greenhouse gases.
Most defenders of the Greenhouse Gas Theory therefor use night time conditions to attemt to explain the existence of a greenhouse effect.
Yet its quite clear that all the atmospheric effects merely slow down the heat loss from the Earth surface.
There is no warming never mind heating of the Earth surface.
What part do the IR active gases play in this slowing down the heat loss?
Very little measurable effect.
For instance Latent Heat of Vapourisation of Water plays a much bigger role
This is why ‘warms’ the surface is an ambiguous term and is best avoided.
tallbloke 10:34pm: Seemed like Stephens context was drawing conclusions from atm. volume.
Stephen 10:45pm: “Pressure changes around that (1000mb) figure represent the ongoing negative system response to any forcing elements other than mass, gravity or insolation.”
Plus oceans and other multiple forcing elements. Again, I was writing about Stephen’s volume context.
If 1000mb had an answer in it, how could T & P vary oppositely on weather stations? PV not= nRT?
No sure answers on positive or negative system response come from just mass, gravity, insolation b/c oceans and multiple forcing elements confound us. You are right to agree global near surface Tavg. varies, not fixed by stable mass, insolation, gravity and varying atm. volume.
Better for a planetary atm. to think about P=density*R*T.
Oh Tim, you missed an entire post of mine to you.
Tim Folkerts… this was to you:
P = εσA(Th⁴) is what you use for a surface radiating into a vacuum, and it is also what you can use for a surface radiating into an ambient environment at least three times cooler than it is.
P = εσA(Th⁴ – Tc⁴) is what you use for a surface radiating into an ambient environment of a similar but cooler temperature, like the ground radiating into the atmosphere.
In case you can’t tell, that Th⁴ would be the 396 W/m^2 from the ground, and the Tc⁴ would be the 333 W/m^2 from atmosphere, so the actual figure you should have been using all this time is 63 W/m^2 from the ground, because that is what back radiation actually does.
Oh, note of course that those values are assuming the ground temperature includes a fund of vibrational energy dedicated for IR emission only, as well as an extra fund of vibrational energy for conduction/convection that for some reason does not change the ground temperature… must be sneaky ninja vibrations, right?
Stephen, could you explain a bit more of what you were thinking when you said “because one needs the change in Rspecific to offset the change in density that results from expansion or contraction” ? You seem to keep changing a constant for a given ratios of gas compnent concentrations (Rair) to affect control on density fron an assumed T change and I don’t understand you there. (well, seems I don’t understand very much of your line of thought)
You say: “which would reduce the density of the troposphere for a cooling effect”… you do understand that is totally backwards to the IGL equaion?
I’m lost.
wayne said:
“You cannot say that with more solar energy you get warming an increase in columnar volume (true) but since the volume increased the temperature is compensated and remains the same (false).”
I’m not saying that. With more solar energy, more mass or more gravity you get a rise in both T and V because the extra energy available offsets the reduction in density.
With a change in anything else you just get a change in V alone but then additionally the relative quantities of KE and PE change to affect T but that additional factor is not in the Ideal Gas Law.
I think that my description at 10.52 is correct so how to reconcile that description with the Ideal Gas Law ?
The answer must be to accept that the Ideal Gas Law relates to parcels of air within an atmosphere but cannot relate to an entire atmosphere because P is then fixed which prevents the relationships from working together in the way that they do when a parcel of air is able to adjust P by moving up or down.
We need to create a new Law that takes account of the distinction.
So I suggest this:
VT = nRE
(where E is KE + PE)
So that would result in the following:
i) Increase V so that KE falls due to more energy having been converted to PE which results in T falling so that the equation stays balanced.
ii) Decrease V so that KE increases due to less having been converted to PE which results in T rising so that the equation stays balanced,
The point being that for a planet as a whole with fixed P the new variable is the changing proportions of KE and PE.
That then allows an inverse relationship between T and V similar to the old inverse relationship between P and V.
The new relationship carries out the same function of maintaining thermal balance at top of atmosphere.
I think the point is clear from my words but being unfamiliar with the manipulation of equations I’m not sure that I’ve set out the proposed new equation correctly so comments as to that would be welcome.
Rog:
I think this is another way to describe the outcome:
i) Increase E by introducing more GHGs so that V increases and more KE is converted to PE so T fails to rise. The equation is balanced by equal increases in E and V.
ii) Decrease E by removing GHGs so that V falls and less KE is converted to PE so T fails to fall. The equation is balanced by equal decreases in V and E.
So please delete the post at 8.05 which is wrong because one cannot start by changing T, One has to start by changing E or V and then the relationship between PE and KE within E prevents a change in T.
Thanks.
Done. OK, this is an interesting move. As I said last night, planetwide average pressure is pretty much constant at timescales relevant to GW discussion (as Stephen has also pointed out earlier). So it seems to me to be a legitimate move to treat Pressure as constant for an energy budget discussion. But does that mean we can remove it from the equation altogether as Stephen has done with his new equation and still have a valid set of relationships?
It seems to me that it is OK provided that the amount of liquid water in the air doesn’t change. But this clearly isn’t the case over long timescales, as we know that glacial periods are much drier. With less water aloft, pressure is reduced. Variability in the water cycle on shorter timescales during interglacials is the question. How much does it matter?
Pressure varies with altitude.
[Reply] True but not important to this aspect of the discussion.
The interesting thing is that out in space Temperature is inversely proportional to Volume for any gas accumulation so my reordering of the equation complies with real world physics outside an atmosphere.
It is only at within an atmosphere that the relationship can turn out the opposite due to the combined effect of Pressure and surface heating interfering with the normal relationship.
The discrepancy is then resolved by lifting molecules upward against the force of gravity until the molecules are again at the correct temperature and pressure for their height. That correct temperature being set only by mass, gravity and insolation. That is what my adiabatic loop does.
For a planet floating in space and with a thermal equilibrium between the top of atmosphere and the external energy source the pressure at the surface is only relevant for setting the height that the atmosphere needs to attain at equilibrium.
P is already incorporated in V on one side of my equation and in the relationship between KE and PE on the other side so we can leave it out altogether.
The lifting of the molecules against the force of gravity removes the temperature difference between surface and top of atmosphere by converting 100% KE at the surface to 100% PE (nearly) at the top. The only reason PE doesn’t quite get to 100% at the top is because the temperature of space is above absolute zero.
All the KE at the surface gets smeared across the vertical height until it is all in the form of PE so that it has no effect on top of atmosphere energy balance.
If one increases mass gravity or insolation then the addition of new heat ensures that the relationship between PE and KE stays the same enabling V and T to vary together.
If one changes anything else such as radiative characteristics then there is no energy being added to the system, merely a redistribution of available energy within the system so any increase in PE has to be at the expense of KE and vice versa so that V changes but not T.
The only remaining question is whether CO2 really does increase E but either way it doesn’t matter because the net effect would be corrected by the Volume change with no change in T because the net effect only involves a change in PE leaving KE (and T) the same as before.
Going on now to the issue of water vapour.
All the evidence is that specific humidity stays very much the same on time scales relevant to AGW even if the speed of the water cycle changes.
I suspect that the amount of water vapour only changes if one also changes mass, gravity or insolation so that there is more energy in the form of KE in the system to fuel evaporation.
Thus the changed insolation from Milankovitch cycles could change total humidity by increasing both PE and KE in parallel. The same for more mass in the atmosphere or a stronger gravitational field.
Changes that only affect PE such as radiative characteristics would not affect humidity and we have seen no significant global humidity changes in response to increasing CO2.
Correction needed, it is hard to get t all right ‘on the fly’.
I said:
“If one changes anything else such as radiative characteristics then there is no energy being added to the system, merely a redistribution of available energy within the system so any increase in PE has to be at the expense of KE and vice versa so that V changes but not T.”
However energy is being added to the system in the form of more total E because KE is the same but PE increases.
It is just that not enough is being added to raise both PE and KE because V has to change in order to match energy in with energy out at top of atmosphere as per my description at 10.52pm.
Might be other adjustments to the words needed but I think I’m getting there having formulated the new equation.
It isn’t easy getting the consequent narrative exactly right.
Strictly speaking a surface is not necessary, Jupiter is hotter as you head towards the center, and there is only speculation about whether there is a significant rocky core, but it is certaintly not very important either way.
Stellar fusion is an outcome of adding enough mass to a column of gas with no solid surface at all.
Adding too much results in an event horizon.
“Strictly speaking a surface is not necessary, ”
Not sure about that.
With no surface T is inversely proportional to V for the entire gas ball.
At a surface that relationship is disrupted until the height adjustments have been made.
It will take some time to work out all the implications of that new equation – assuming no one can say that it is flawed and I’m waiting on that before going deeper.
Stephen says: “The problem with the account of Tim and Bryan is that they propose that the effect of GHGs, by reducing the rate of heat loss, both warms the surface AND expands the atmosphere.”
Take 1 m^3 of gas near the surface. Seal it in a flexible adiabatic container. Add energy to the gas.
As a result the The container will both expand a bit AND the gas inside will warm a bit.
The problem with Stephen’s account is that he seems to be proposing that the gas will expand with no change in temperature.
[Reply] Ah, PET bottle kitchen science done without the PET bottle….
Steven Wilde says
“the Ideal Gas Law ( IGL )….. cannot relate to the whole atmosphere”
Let us assume average pressure (p ) of the atmosphere is constant. Actually pressure changes steadily going up. ( Lapse rate )
PV = nRT let P = a constant, then
V = a constant x T
V is directly proportional to T ( Boyle’s Law 1662 )
The atmosphere is not a sphere it is thicker at the hot equator and thinner at the cold poles. A greater volume of air where it is hot and and less volume where it is colder.
That is a greater T leads to greater V, in line with the IGL.
How does the radiative theory explain the changing height of the atmosphere ?
Steve also says
“out in space Temperature is inversely proportional to Volume for any gas accumulation ”
Please explain what you mean by this .
If you look at Jupiter, the temperature and pressure increase together all the way down.
http://math.ucr.edu/home/baez/entropy.html
Steven Wilde says
“the Ideal Gas Law ( IGL )….. cannot relate to the whole atmosphere”
Let us assume average pressure (p ) of the atmosphere is constant. Actually pressure changes steadily going up. ( Lapse rate )
PV = nRT let P = a constant, then
V = a constant x T
V is directly proportional to T ( Boyle’s Law 1662 )
The atmosphere is not a sphere it is thicker at the hot equator and thinner at the cold poles. A greater volume of air when hot and and less volume when colder.
That is a greater T leads to greater V, IGL gets it right, as usual.
Steven also says
“out in space Temperature is inversely proportional to Volume for any gas accumulation ”
Please explain and give evidence for this statement .
“
So far, we’ve seen the entropy of a gas cloud actually decreases as it collapses under its own gravity. At this point, you should be dying to see how I’m going to rescue the 2nd law of thermodynamics! But before I do that, I want to point out another odd fact: our gravitationally bound ball of gas has a negative specific heat! In other words, the less energy it has, the hotter it gets.
To see why, let’s figure out the relation between the temperature and energy of this ball of gas. Remember, the virial theorem says that K = -P/2, so P = -2K, so the total energy of the gas ball is
E = K + P = -K
On the other hand, we’ve already said that
K ~ NT
so we must have
T ~ -E/N
In other words: THE LESS ENERGY THE GAS HAS, THE HIGHER ITS TEMPERATURE BECOMES.
Sounds paradoxical, eh?
It’s not really so weird if you think about it. As the gas ball collapses, it loses energy: the kinetic energy goes up, but the potential energy goes down even faster! Since the kinetic energy goes up, the gas gets hot. Energy goes down, temperature goes up!
In fact, it’s typical for a gravitationally bound system to have a negative specific heat. Imagine a satellite so low that it starts running into the earth’s atmosphere and spiralling down. As it loses energy, it gets hotter, and finally burns up!
This feature of gravitationally bound systems makes them quite tricky. Only systems with positive specific heat can be in thermal equilibrium with their environment. So gravitationally bound systems can never be in thermal equilibrium with their environment! They always want to keep shrinking, thus losing energy and gaining entropy.” ~Baez
___________________________
Still wondering if no one other than tallbloke sees the significance in the correction of: P = εσA(T⁴) to: P = εσA(Th⁴ – Tc⁴) for a surface radiating into an atmosphere of similar but lower temperature?
Stephen 1:03pm: “..assuming no one can say that (VT=nRE) is flawed and I’m waiting on that before going deeper.”
Check the SI units. Here’s what I get first try, anyone else?
VT=nRE
T = nRE/V = (length^0.5)/sec which seems odd. T should come out in Kelvin, an SI base unit.
Roger Clague asked:
“out in space Temperature is inversely proportional to Volume for any gas accumulation ”
“Please explain and give evidence for this statement .”
A ball of gas gets hotter when volume decreases and colder when volume decreases.
In space the only means of shrinking volume is by increasing mass and the gravitational field arising from that mass so more massive molecules will give a higher temperature for a smaller volume and less massive molecules will give a lower temperature for a larger volume.
But at the moment my main concern is as to the validity of the new equation that I proposed.
It looks to me that it works.
Roger also said:
“Let us assume average pressure (p ) of the atmosphere is constant. Actually pressure changes steadily going up. ( Lapse rate )”
Contradictory. You cannot assume P as a constant when it declines steadily going up.
For an individual parcel of air within an atmosphere P can vary because the height of the parcel can be changed.
For a planet with an atmosphere viewed from outside P cannot change because surface P is the same whether the atmosphere expands or contracts.
So one needs a different equation than the Ideal Gas Law to deal with an entire atmosphere correctly.
That equation needs to bridge the gap between decompression causing a fall in temperature and compression causing a rise in temperature (my adiabatic loop).
Both processes are competing and are in balance within an atmosphere at equilibrium.
If one increases the energy that the system is capable of holding by increasing mass, gravity or insolation then both processes ramp up equally so both T and V can change.
If one does not increase the energy that the system is capable of holding but instead just change the speed at which energy flows through then only V can change.
Think of a jar of water filled to the brim.
Adding more water without increasing the size of the jar increases the volume of water but the excess just flows straight out and you have no more in the jar than before.
Mass, gravity and insolation in combination set the size of the jar.
More KE supplied to the atmosphere without increasing the amount that the atmosphere can hold just leads to that KE flowing straight out.
The increased atmospheric height and the consequent conversion of more KE to PE represents the extra KE flowing straight out to PE.
On the other hand a decreased atmospheric height and the conversion of more PE to KE represents more KE flowing back in.
You can also consider the variable store of PE as an overdraft facility that the atmosphere can draw on to maintain stability.
The biggest conceptual problem for radiative theory enthusiasts is grasping the idea that V and E (in the form KE + PE) can change in tandem without involving T.
My equation shows how it can be done by placing T and E on opposite sides of the equation and then allowing KE and PE to vary freely in response to a change in V.
I’m reconciled to this idea taking some time to register even if it is right.
Hi Trick. I think we need to expand this one out.
……..(number of moles) *
(molar mass constant)* (KE+PE)T= _______________________________________________________
………V * (average atomic weight of proportionate constituents) *
(molar mass constant)Which looks like it ends up as Joules per volume, which sounds half reasonable. I might be wrong though.
tallbloke 4:40pm: T should come out simply in degrees Kelvin, right? Base SI unit. Anything else is an issue, maybe not a problem. See if anyone else tries, I can go thru each step later, hard to type quickly, readably as your post is difficult to interpret. KE+PE units are mass * (length/sec)^2.
Stephen 4:27pm: “In space the only means of shrinking volume is by increasing mass…”
A “cloud” of gas in space can still contract its volume with fixed amount of mass. Saturn has been doing that contraction slowly long time, pushing out more heat than it receives from sun. See Kelvin-Helmholtz mechanism.
As the link to Baez’s page and quote I provided mentioned, gravitationally bound system has a negative specific heat, so we have to toss out any illusions that it will be in thermal equilibrium with it’s environment.
Similarly while volume decreases, temperature and pressure increase, yet energy and entropy both decrease.
What’s that I said? Entropy decreases?
Yes, Baez left it as work for the reader, but here’s the answer: radiation carries away a lot of entropy.
As a hypothetical non-radiating gas can not undergo this loss of entropy to the background of space, there is absolutely no reason to assume it will be in ANYTHING RESEMBLING AN EQUILIBRIUM STATE THAT IS ANYTHING LIKE OUR OWN ATMOSPHERE… the inability to lose energy gained by collisions with lower molecules means the column of gas would be much taller, if it even remained associated with the surface rather than winding up scattered to infinity.
Trick: Although K is a base si unit, it doesn’t tell us much about how it arises. Wiki says this about the stat mech approach to temperature:
Statistical mechanics approach to temperature
Statistical mechanics provides a microscopic explanation of temperature, based on macroscopic systems’ being composed of many particles, such as molecules and ions of various species, the particles of a species being all alike. It explains macroscopic phenomena in terms of the mechanics of the molecules and ions, and statistical assessments of their joint adventures. In the statistical thermodynamic approach, degrees of freedom are used instead of particles.
On the molecular level, temperature is the result of the motion of the particles that constitute the material. Moving particles carry kinetic energy. Temperature increases as this motion and the kinetic energy increase. The motion may be the translational motion of particles, or the energy of the particle due to molecular vibration or the excitation of an electron energy level.
So in one sense, it seems Stephen is ending up with KE on both sides of his equation, which might be a problem, because if they cancel, there won’t be anything left on one side of the equation. DANGER! WILL ROBINSON 🙂
Please do go through your working, it will be instructional, and emotional, probably. 🙂
Stephen, TimF is right, you seem to imagine that if you heat a parcel all goes into the expansion and that is blatantly incorrect. The expansion is one R(universal) worth, the other cp minus one R(universal) goes into all of the degrees of freedom of that gas mixture and part of that is a linear velocity increase (temperature also goes up) That IS the difference in ‘cp’ and ‘cv’.
Next, in E = PE + KE, that is probably incomplete, should be something like E = KE + k.PE or E = k.KE * PE, take you choice, for I bet ‘k’ will not equal one, that is, one unit or KE probably does not equate to one unit of gravitational PE from additional height.
Next, you are missing a ‘divide by m3 or divide by V (volume)’ in you energy term.
V.T = n.R.(E/m3) or V.T = n.R.(E/V) or just cancel both volumes to T = n.R.E or T = n.R.(KE+k.PE).
At least now the units are correct if that now makes any physical sense to you.
You seem to be looking for some equation that says the Earth can not warm or cool because of a volume change or something else will cancel the temperature change. Well, good luck.
However if you are looking for something that cancels *part* of the warming from an additional amount of energy, I gave that explanation to you long ago in my comment on how the atmosphere ‘puffs up’ or the volume increases in the day and contracts at night returning *part* of the energy to temperature. I pointed at UniSys’s site to show this occurring. But Stephen, that is only one R(universal) fraction of the energy in question of the ‘cp’, not the entire ‘cp’ heat capacity.
Steven W says
“So I suggest this: VT = nRE
(where E is KE + PE)”
That is
VT = a constant
This predicts increase in T reduces V
But we find in our atmosphere increase in T increases V. The troposphere height is greater at the equator than the poles.
So your equation makes incorrect predictions.
Steven W says
“You cannot assume P as a constant when it declines steadily going up.”
It is you who decided to make pressure ( p ) a constant. I am agreeing with that and saying why.
The IGL was discovered from experiments on small volumes at the surface. It was assumed that gravity was constant at top and bottom.
In the atmosphere there is a pressure profile because gravity does decline and has a noticable effect over the larger distance.
The “average pressure” is that which would exist if gravity did not also decline steadily going up. As is assumed for the IGL.
Wayne: T=nRE was what Stephen was proposing. Thanks for the elucidation which helps expand it out and illuminate the consequences. SO, are you happy with T=nRE as well? Is this a novel formula? I appreciate you were already there with your own descriptive analysis. Is this the convergence we have been awaiting?
So in stat thermo terms can we consider T to be the expression of KE as wikipedia says? If so, what are the consequences? Would we be left with KE=1/n.R.k.PE ?
Well I think it is clear that expansion results in more PE relative to KE when the amount of KE is limited by energy coming in from outside the atmosphere plus the ability of mass and gravity to be able to hold on to it.
The issue then is whether the increase in PE utilises all the KE generated when (or if) a GHG causes net warming.
Contributors here are suggesting that somehow the amount of mass , gravity and insolation does NOT limit the amount of KE that an atmosphere can contain. I think that requires some explanation.
How exactly could an atmosphere retain more KE if mass, gravity and insolation are all unchanged ?
Furthermore we are not all agreed as to whether CO2 has a net warming or a net cooling or a zero effect.
Suricat and others have pointed out that water vapour does not change the lapse rate (thereby expanding the atmosphere) by virtue of its radiative characteristics but rather via the phase changes of water.
Ozone in the stratosphere changes the lapse rate (thereby expanding the atmosphere) by virtue of its interaction with incoming solar energy which is quite different to the proposed AGW interaction of CO2 with upward longwave from the surface.
In the cases of the phase changes of water and the ozone reaction with incoming solar energy why would the expansion not absorb all the extra KE as PE ?
So does CO2 have a net warming or cooling effect or is its effect zero ?
More absorption is matched by more radiation isn’t it so why would there be any net warming or cooling given that the extra absorption results in a new radiative window to space?
If the net effect of CO2 is zero we no longer have to consider whether it expands or contracts the atmosphere in the first place.
Two questions arise from the above:
i) Can an atmosphere hold on to more KE (without it converting to PE) if mass, gravity and incoming energy remain the same ?
ii) Is the net effect of more CO2 warming, cooling or zero ?
The answers will determine whether or not I am barking up the wrong tree.
I would apologise for wasting everyone’s time if I turn out to be wrong but in this case I think my questions are reasonable given the apparent paucity of knowledge on both those issues.
Tallbloke, I don’t know yet. I prefer a slow pace to let it roll around upstairs a bit, rearrange the equation and terms, try some actual cases to see it makes physical sense.
One thing, volume is completely gone. What do we have? A ‘T’, ‘R’ and ‘n’ number of moles …
Wait a second !!! Something seems wrong in that first equation and I accepted and used it without a question:
V.T = n.R.E, that doesn’t seem right at all.
PV = nRT –> T / V = P / n.R ….. ???? Sorry, I didn’t start far enough back in all of these comments.
Oops, I need to go back and see how Stephen even came up with that V.T = n.R.E equation, it seems something’s amiss.
Have a b-day party I can’t miss so may not be back till this eve on this.
[Reply] My bad, I forgot about the V on the left.
wayne said:
“T = n.R.E ”
I was hoping someone would refine my equation to the minimal form but is that right ?
A rise in E being the total of RE + PE would give a rise in T BUT within E PE is replacing KE to prevent a rise in T.
Do we need and adjustment in there to account for the conversion of KE to PE ?
We need V on the left to deal with the effect of the KE to PE conversion on the right don’t we ?
I’m curious what the virial theorem effect is here…
For a gravitationally bound ball of gas which is on average unchanged and the positions and velocities are bounded, you then have KE = -PE/2.
*Which on average has temperature unchanged* is what that should have said.
wayne 6:04pm: “V.T = n.R.(E/V) or just cancel both volumes to T = n.R.E”
Need VT=nREV to cancel V from both sides. Your actual result would have V^2 on the left (multiply both sides by V).
tallbloke 5:39pm: “Please do go through your working, it will be instructional, and emotional, probably”
Emotional? Around here? Nahhh….
I can think of one mistake I might have made, will double check & post later; won’t end up Kelvin on RHS even then. Maybe someone beats me to it. It is ok to end up with KE on both sides, in fact need to end up with KE or “some unit” the same on both sides, ha. Kelvin=Kelvin is what is needed for T=nRE/V. Don’t see a Kelvin in RHS of your 1st try 4:40pm.
See, not even something as basic as a unit is easy. I commend a Prof. or TA for pointing that out to me (gruffly & in red) on some exam right after a -5 points or something.
The tricky bit is how best to incorporate the effect of the KE to PE conversion as a response to V so that T (and KE) remains dependent on mass gravity and energy supply from outside the atmosphere.
I’ve had a go at coming up with a suitable equation but I think it is beyond my mathematical skills.
The conversion of KE to PE as a result of changes in V caused by changes other than mass gravity and insolation would seem to be best represented as a separate process independent of the main show but I’ve no idea how to express that mathematically.
To my mind TV = nRE seems to work well enough as long as the constituents of E namely PE and KE are free to vary freely in response to changes in V because that also affects T but perhaps there is a more convincing way to express the relationships since I see that some here are not convinced.
I may just have to leave it at that and see what transpires.
Let’s keep it simple.
Add say I kg of CO2 to an atmosphere.
Assume that CO2 has a net warming effect (it might actually have a net cooling effect).
That 1 kg of CO2 provides say 10 Joules of extra energy which raises the atmosphere 1 metre.
I know the proportions are unrealistic but we are keeping it simple.
That extra 10 Joules has to be supplied constantly if the atmosphere is to stay 1 metre higher.
Meanwhile the extra 1 metre height has converted 10 Joules from KE to PE.
How is the temperature expected to increase ?
If the atmosphere had NOT expanded and converted the extra Joules to PE then there would have been an imbalance at top of atmosphere with too much KE in the system and more going out than coming in.
The fact of the expansion prevents any such imbalance.
PE is our global thermostat.
I say the equations have to follow reality rather than vice versa. We should be able to construct equations that cover that scenario.
Is there anything here of use? Various ideal gas equations…
http://en.wikipedia.org/wiki/Isentropic_process
Thanks Oldbrew.
A bit technical for me but someone might be able to use it.
tallbloke 5:39pm “Please do go through your working..”
Units used in IGL from here which may itself have flaws so find your own 1st principle I’m lazy, and given SI has 7 base units that aren’t derived:
http://www.webqc.org/ideal_gas_law.html
and kinetic energy = ½ mass*velocity^2 = ½ *kg* (metre/sec)^2, drop the unitless ½ my choice or carry the 1/2 might be your choice, if so, DIY:
KV=nRE
K*metre^3 = mol * (Joules/mol-K) * kg*meter^2/sec^2
Multiply both sides by K, divide both sides by metre^2, cancel the mol/mol:
K^2 * metre =joules*kg/sec^2
A joule is energy expended by force of 1 nt moved thru distance 1 metre.
K^2 * metre = Nt*metre*kg/sec^2
Cancel metre both sides, take square root both sides:
K = (Nt*kg)^0.5/ sec.
K= (force*mass)^0.5/sec.
This above is odd in and of itself.
Sec. and mass are base units, force is derived unit so can take this further with F=ma=kg*metre/sec^2; this is where I screwed up earlier. Happens. Press on regardless, sub. in Force = kg*metre/sec^2.
K= (kg*metre/sec^2*kg)^0.5/sec
K=(kg^2/sec^2 *metre)^0.5/sec
K=Kg/sec * metre^0.5/sec
K= (length^0.5) * mass/sec^2
These are all SI base units. So the last eqn. units (if replicable) says this is how a Kelvin is derived but a Kelvin is a base unit also, so there is a flaw somewhere. Unless someone spots another “issue which may not be a problem” in my SI “working”. Which is maybe possible and if so, definitely emotional.
Stephen 9:13pm: “Add say I kg of CO2 to an atmosphere. Assume that CO2 has a net warming effect (it might actually have a net cooling effect).”
Neither happens net if the CO2 is added at the same temp. from existing carbon & O2 at that temp.
The C & O2 simply convert their existing energy into CO2 say by Stephen’s breathing (well, unless if E=mc^2 is important & it is not). Cannot warm (increase) nor cool (decrease) net energy unless energy is added or subtracted to/from earth/atm. system. This is why control volumes are so important and why they invented 1st law.
The infrared active gas CO2 affects the flow of energy, slowing the cooling of the surface and up to somewhere thus slowing the warming of the upper atm. by the exact same amount since the energy doesn’t flow there conserving energy in the earth/atm. system. 1st law is important as is control volume to see 1st law accounting for energy is conserved.
“That 1 kg of CO2 provides say 10 Joules of extra energy.”
No it doesn’t unless you want to use e=mc^2, convert some mass to energy, which isn’t the case.
“How is the temperature expected to increase?”
Net, it doesn’t. Energy in the control volume is the same, simply breathe in change C and O2 into CO2 which affects the energy flow only within the system, no net energy added.
“The fact of the expansion prevents any such imbalance.”
There is no atm. net expansion, no energy changed in the control volume of the earth/atm.
“We should be able to construct equations that cover that scenario.”
We can but not considering mass, insolation, gravity only – have to use them, control volume & albedo, atm. emissivity in 1st law equil. condition as up there in the top post (roughly give or take some rounded numbers):
1370 * 0.7 – 4*sigma*(1-0.8/2) * Tsurface avg. ^4 solve for Teq. atm. near surface =289K
Spending so much bandwidth on PV=nRT why not just spend it understanding the provenance of something like this that works fine, in concert with all the thermo grand masters findings and experiments.
Quoth tallbloke again: “…go through your working, it will be instructional, and emotional, probably.”
Trick: I think where we are heading to, Albedo will turn out to be emergent from the fundamentals. We won’t need to have it as a given. Better to go the other way round from gas laws and latent heat which actually control near surface to tropopause. Not radiation only model.
Yeah tallbloke. Both IGL and radiation are cool to learn about, don’t exclude either I say. Though some more bandwidth spent on hacking thru radiation would be helpful. Certainly albedo will change, it does now – it is hard to measure and we don’t have records like global spatial and temporal sampled Tavg. over the century. Figure albedo out from internal flows if you can, then apply result to radiative flows – the one & only game in town for external earth/atm. system energy flow.
Science will get better at albedo measures I bet. Maybe even atm. global avg. emissivity measures eventually.
Want/need (Aristotle terms) to get a handle on both Stephen’s adiabatic and diabatic process. That means internal control volume energy flow (thermals, evap. transp.)and external control volume energy flow (SW in, LW out radiation).
That LW is so pesky, can’t “see” it, ghost like. Faith based? No, my bare feet, cloudy night temperature difference vs. clear night & logical science learned from reliable thermo grand master 1st principles et. al. sources doing relevant experiments say LW must exist in significant quantity even if can’t see it.
Would you say the atmosphere is bound by gravity?
In rough hydrostatic equilibrium.
TB.
I thought this thread was dead. The new ‘page’ style configuration threw me a bit as well, but ‘my how this thread has progressed’ (I’ve spent most of Sunday reading it)! 🙂
I think Stephen’s new attempt at a formulation originated from here:
Where I hinted that the DALR didn’t/couldn’t include include latency for an ‘ELR’ (environmental lapse rate), or a ‘WLR’ (wet lapse rate) when implementing the PV=nRT equation. Thus, can’t represent Earth’s atmosphere as a ‘true’ analogy.
IMHO. A change in the constant R isn’t the correct approach when considering a WLR, so I suggested a ‘binary’ formula that measured the ‘latency’ properties of the system.
I repeat this post here:
“Stephen Wilde says: January 17, 2013 at 9:02 pm
“Does that make more sense?”
It’s beginning to. Let’s go back to the original equation of “PV=nRT”. This works fine where the ‘Molar’ constituents remain unchanged, but this isn’t the case for Earth’s atmosphere. WV is added to the atmosphere at the Earth’s surface and precipitated out at some altitude or other. This ‘equation’ needs to be modified/edited for a better representation that can model Earth’s atmosphere.
We need to add a P2, V2, n2 and T2 to accommodate the ‘phase transition’ elements.
Best regards, Ray.”
Feel free to read the entire thread, but the important point here is to arrive at a ‘formula’ that describes the WLR better than Stephen or I can (my math ‘sucks’ too). 😦
Any suggestions? 🙂
Best regards, Ray.
I mean is it likely that the atmosphere will spontaneously cease to be found within a given volume surrounding the gravity well?
There is an upper bound on the position and volume for a gas cloud in a gravity well assuming work is not done to it.
So one can say it is bound by gravity, right?
What does that mean for the specific heat of that atmosphere?
Max asks – “..is it likely that the atmosphere will spontaneously cease to be found within a given volume surrounding the gravity well?”
If earth like g well, a molecule of N2 won’t spontaneously achieve escape velocity. It is non-zero possible to get a spontaneous kick to high N2 velocity but the probability is near nil that velocity would be greater than 22,500 m/sec. N2 velocity most probable by M-B distr. is around 400 m/sec at the surface, going down at altitude as N2 (T)^0.5.
I interpret Max has an answer for the Cp, fill me in.
A column of gas suspended in a gravity well does not behave in what might be considered “typical” manners for a system which is in thermal equilibrium.
If you poured a cloud of gas into a container sitting in a gravity well, as the gas molecules began to fill the container the distribution would not be even throughout the container, and as the density near the bottom increased, so would the temperature there.
…
What is less obvious is that this would reduce the energy and entropy of the gas column as a whole.
…
Why would that be the case?
The position phase space of column of gas collapsing under gravity is necessarily reduced for the molecules near the densest regions, one would expect the momentum phase space to expand, but if this were the case the cloud would not collapse under gravity.
If both portions of the phase space shrink, the entropy goes down for the gas molecules, which should be setting off “HERESY” alarms in your head by now.
Don’t fret though, emission of radiation by the gas molecules allows the entropy to increase and escape the gas cloud, as radiation is a great way to jack up the entropy of a system.
In the case of a non-radiating system, there must be something carrying entropy away or else the system will not collapse under gravity.
For a globular cluster the evaporation of stars from the cluster serves this purpose, and similarly for one of the oft-discussed hypothetically non-greenhouse atmospheres, the only way to carry away entropy would be to lose molecules directly.
…
These situations I am describing are cases where a system would have a negative specific heat, losing energy raises the temperature in system collapsing under gravity.
Thermal equilibrium assumptions require positive specific heat, and thus any such arguments which hinge upon flatly declaring “1st law” or “2nd law” or whatnot should probably be checked for this source of error.
While yes, the laws of thermodynamics do hold, they do not always hold in the manner you expect.
First, thanks Trick for catching my slip on the V². That was a dumb one. I learned don’t write a complex comment while also trying to get ready for a birthday party! 😉
Stephen, let’s start over. I do seem to sense what you are trying to get across by saying all of these words but it seems a bit confusing to me.
You may not realize that the KE > PE and PE > KE you keep speaking of are already embedded within the Ideal Gas Law itself. I’ve mentioned this before but for one last try look carefully at the form of the IGL:
R is the universal gas constant
Rair = n × R / m
ρ = V / m
so,
P / ρ = Rair × T.
Rair is the specific gas constant for air as we now know it today. For a moment, let it remain constant with no additions or removals of water vapor or co2 that do cause a slight change in that value.
‘n’ is the number moles in a one square meter gas column, for the same reason, let that remain constant for a moment.
Same for ‘P’, keep the mass of the column fixed. That will flex with changes in the composition also.
By that equation of the IGL, if ‘T’ rises, the density has to decrease so that the ‘P/ρ’ ratio proportionally rises.
You can now see this example two different ways depending on your preferred viewpoint.
If you are thinking of a fixed one cubic meter or unit control volume, since the density dropped, some of the particles within were forced out of that unit cube and since we are also speaking of that unit cube being within a unit area column the particles forced out go strictly upward, lifting the column above and some KE > PE.
If you are viewing it as a variable height cube or even as an entire unit column as a whole, then after the density drop caused by the ‘T’ increase, the volume or column will be taller so once again some KE changes to PE.
In both cases KE > PE, the effects are identical, but that is being accounted for in what the IGL implies itself. You cannot then say that KE > PE recursively causes further changes through the IGL to alter the original causal ‘T’.
Do you agree with just that much? If so, that clarifies one whole slew of words and we might then tackle what happens when the actual composition of the column’s air is altered which it seems to underlie your entire concept.
The IGL is an instantaneous state of the gases that must hold and has nothing to do with why the lapse is the way it is.
I also assume we are still speaking of a multi-decadal world-average column aren’t we?
—
Another matter since it’s fresh and I just read many of your comment, back to lapse rates for a moment. It seems you and I differ in some respects on this subject.
You seem to start at the DALR and I start at a vertical or zero lapse rate. So here’s how I see it and see if you agree or where you disagree.
A non-radiating dry atmosphere would be basically zero or a vertical line on a T by altitude graph. To me this question was answered on one of the Graeff posts. Ferd, br1, and I all did simulations and they showed no natural DALR lapse, in fact, none at all.
Now add some radiation, emissions and absorptions, occurring within the gases, h20 and co2 but no state change yet, I see two completely opposite effects occurring at this isolated pointi n the example.
At the top few kilometers just under the ToA, radiation is escaping to space increasing as you get closer to the ToA, and that cools the top of the atmosphere pushing that vertical lapse line (0.0 K/km) on the graph to the left or cooler, leaning it over counter-clockwise. In the bottom few kilometers just above the surface there is great absorption due to the high density of the gases and this warms the lower portion pushing the bottom of that lapse line to the right, or warmer, again counter-clockwise. Since there are no state changes occurring at this point in this example, you end up at the DALR, -9.8 K/km slope.
From here on we may agree.
Now add water vapor’s state change to the picture. Near the surface you have evaporation which cools the lower atmosphere pushing the bottom of that line back to the left or cooler, clockwise this time, just a bit though. At or below the ToA, you have condensation and warming that pushes the top portion of that line back to the right, warmer and clockwise again. You end up at the averaged ELR, -6.5 K/km.
Add even more state changing water vapor and it even magnifies both of those effects, top and bottom, above and below, rotating the line even further clockwise to the wet lapse rate of even further, sometime much more, to or past the -5.0 K/km and you have an unstable atmosphere and storms.
Do you see it that way or where might we differ?
Thanks for the considered comments wayne. There is a lot there for me to consider but a few points stand out:
i) “Same for ‘P’, keep the mass of the column fixed”
I’m puzzled by that. Isn’t pressure a consequence of the strength of the gravitational field too ?
Furthermore the mass of the column isn’t fixed unless you also widen the column with height to reflect the spherical nature of the planet. The mass of the entire atmosphere is fixed but each unit of volume within the atmosphere has less mass if the atmosphere expands.
ii) “cannot then say that KE > PE recursively causes further changes through the IGL to alter the original causal ‘T’.”
I’m not saying that. I’m saying that the temperature will depend on the amount of KE but the height of the atmosphere depends on KE+PE.
The amount of energy flowing through MUST be regulated so as to match energy in at top of atmosphere so if one keeps the incoming energy the same but there is more KE than needed to balance it then one can only regain balance if one expands the atmosphere thereby converting ALL the excess KE to PE. So you don’t get a rise in T in the first place (except maybe as a lagging feature while the system adjusts) You just get an immediate expansion which keeps the amount of KE steady so as to retain top of atmosphere balance. Assuming GHGs do increase KE in the first place which we don’t all agree on.
If not all the excess KE were converted to PE then there would still be too much KE and thus too high a temperature so that energy out would be more than energy in permanently.
The Earth’s temperature must be exactly right to match energy flowing in. Therefore the amount of KE must be limited to that figure and T must be controlled in some manner. We just need to find the right variant on the IGL.
iii) “A non-radiating dry atmosphere would be basically zero or a vertical line on a T by altitude graph”
My problem with that is that in reality there is a pressure gradient set by gravity and the reduction of pressure with height leads to a lapse rate even with no radiative capability.
Otherwise one would have the impossible scenario of a sudden and complete drop of temperature from that of the atmosphere to that of space at top of atmosphere in the width of a molecule.
It is the pressure gradient that determines the lapse rate which determines atmospheric height and which gradually replaces KE with PE all the way up until the top of the atmosphere is the same temperature as that of space.
So there is a lapse rate set by gravity via the pressure gradient which can never be vertical.
I like the idea of the lapse rate moving clockwise and counterclockwise as one goes up but that is already apparent in the ‘W’ shape of Earth’s vertical temperature profile. But the starting point cannot be vertical due to the pressure gradient.
I’m pretty sure that it is the pressure gradient which biases the starting lapse towards cooling with height that allows total energy (KE+PE) to control the height of the atmosphere rather than just KE.
It is like that jar of water I mentioned. The system can only retain as much KE as gives it the right temperature to radiate out to match incoming energy. Any more and the excess just slops over the ‘rim’ and becomes PE instead.
I think my equation VT=nRE, where E=KE+PE and the proportions can vary, comes close.
wayne.
I can tell you why the lapse rate is not vertical.
That would represent no atmosphere and no gravity like the moon.
The surface gets hot and radiates straight out but from just above the surface upward there is no further loss of energy because there isn’t any.
A horizontal lapse rate represents infinitely powerful gravity and an infinitely dense atmosphere, a black hole where nothing gets out.
The slope of the lapse rate therefore depends on gravity forming a pressure gradient and the stronger the gravitational field the shallower the slope becomes.
So the natural lapse rate for a given gravitational field is actually somewhere between 12noon and 3pm using the clock analogy.
You are right to say that composition can vary the lapse rate but in the end the average of all lapse rates within the vertical column must equal the lapse rate set by gravity.
However it is not necessarily radiative characteristics that change the lapse rate.More likely it is other qualities such as phase changes in the case of water vapour or the absorption ability of ozone when hit by solar shortwave.
I think it likely that radiative characteristics go straight to a volume increase with possibly no change in lapse rate and because the pressure gradient biases the system towards cooling with height it goes straight to PE and not KE simply because it does cause expansion rather than a change in the lapse rate.
Having gone to PE in a higher atmosphere the vertical height of the adiabatic loop increases and it takes longer for KE to be returned to the surface by the descending half of the loop.
So,
IF (not demonstrated to me as yet) CO2 holds more energy for longer then it raises the atmosphere to create a delay in the return of KE from the adiabatic loop to the surface and the net effect on T is zero.
Stephen and Tallbloke:
You guys are going to find this paper a ‘must read’ and very interesting though if you are not that familiar with statistical mechanics, you might just try to grasp the essence of the words:
Atmospheric absorption by IR-sensitive molecules
Click to access IR-absorption_updated.pdf
I came across this after writing my last comment to Stephen, just a few minutes ago, but I can already tell it’s important to know. Here is someone capable of doing the heavy-lifting statistical td analysis. Even has a bit on lapses too Stephen, but I haven’t even read it in detail myself.
—
“You are right to say that composition can vary the lapse rate …”
When you say ‘composition’ you seem to mean water vapor exclusively, I meant any changes in O2, N2, Ar, CO2 concentrations not necessarily including H2O and state change. No, I didn’t say that per se, I said the composition would change all of ‘P’, ‘n’, and ‘Rair’. For me to say that about the lapse rates I would need to dig a bit… the answer to my answer to that is not on the top of my head.
It’ll take me a while, some times hours to read your comment back to me one sentence at a time, so I might comment back a bit later, but that was on comment that popped right out at me. 🙂
[Reply] As I said the other day on the emissivity thread, that paper has much to commend it, though it does confuse ‘heat’ and ‘energy’ more than I like.
“As I said the other day on the emissivity thread, that paper has much to commend it, though it does confuse ‘heat’ and ‘energy’ more than I like.”
Somehow I missed that in the comments but thanks much, I’ll watch out as I read it.
Stephen Wilde says:
January 21, 2013 at 7:43 pm
Question ( i )
THe IGL is a model. We let pressure start off constant. Gravity will create a lapse rate. We ignore the small change in volume caused by increasing height
Question ( iii )
Even N2 and O2 absorb and radiate a bit. So there is always a lapse rate
In ( ii ) you say
“The amount of energy flowing through MUST be regulated so as to match energy in at top of atmosphere”
We are applying the IGL and the Law of conservation of energy ( in particular KE and PE ) to a small vertical column of and within the atmosphere. We assume all columns are the same. So our result is also for the atmosphere as a whole.
We are not considering energy flow in the atmosphere or energy entering the atmosphere.
wayne:
You know things make a lot more sense for my hypothesis if the effect of CO2 is nominally cooling. It goes like this:
i) CO2 in an atmosphere allows more radiative energy out to space than does a less radiatively active atmosphere.
ii) Atmosphere cools and so contracts.
iii) Contraction results in faster conversion of PE to KE by speeding up my adiabatic loop. It speeds up because it doesn’t have to go so high.
iv) The additional KE is attributed incorrectly to the CO2 and is taken to be a net warming effect.
v) But it isn’t because all the extra KE is doing is offsetting the cooling effect of more upward radiation.
vi) Net effect of more CO2 being zero.
Doesn’t it make more sense that way around ?
Roger Clague:
i) You shouldn’t ignore the ‘small’ change in volume. CO2 produces a ‘small’ change in energy flow rates.
ii) My point is that due to the pressure gradient there is a lapse rate even if the entire atmosphere is radiatively inert.
iii) You should be considering energy flow in the atmosphere AND energy entering the atmosphere. That is what makes it all clear. There can be no equilibrium and therefore no atmosphere unless somehow the system always adjusts to ensure that the flow through the atmosphere always results in energy out equalling energy in. Subject to internally generated variations around the mean.
Stephen Wilde suggests “i) CO2 in an atmosphere allows more radiative energy out to space than does a less radiatively active atmosphere.”
No.
Cold CO2 in the upper atmosphere radiates LESS in the 15 um band than the warm ground radiates in the 15 um band. So less radiation will escape to space with cold CO2 blocking the copious IR from the warm ground and replacing it with sparse IR from the cold upper atmosphere (until the surface warms enough to make up the difference).
wayne says: January 21, 2013 at 9:02 pm
“You guys are going to find this paper a ‘must read’ and very interesting though if you are not that familiar with statistical mechanics, you might just try to grasp the essence of the words …
There is no statistical mechanics in this paper as far as I can see, just plain old thermodynamics.
And as Tallbloke says, it confuses heat and energy. And it assumes that a two-sided object emits thermal radiation from only one side. Unfortunately, he then spends ~ 30 pages solving the wrong equations, based on radiation from only one side of an object.
Tim Folkerts says: January 22, 2013 at 1:12 am
“Cold CO2 in the upper atmosphere radiates LESS in the 15 um band than the warm ground radiates in the 15 um band. So less radiation will escape to space with cold CO2 blocking the copious IR from the warm ground and replacing it with sparse IR from the cold upper atmosphere (until the surface warms enough to make up the difference).”
??? 😦
You’re comparing apples with pears! Do you mean that the “15 um band” isn’t so profuse/radiant where CO2 is cold at that altitude? Surely that can only indicate that most of the 15 um band has already been radiated above TOA?
How does CO2 cause “blocking” of the “copious IR from the warm ground and replacing it with sparse IR from the cold upper atmosphere”???
I avidly await your response, but I need to sleep just now. 😉
Best regards, Ray.
Whoa, that Reynen paper getting posted just now is trippy, that’s what I was ranting about in the adiabatic thread.
“How does CO2 cause “blocking” of the “copious IR from the warm ground and replacing it with sparse IR from the cold upper atmosphere”???
With all due respect, if you don’t understand the basic IR properties of GHGs (they absorb and emit IR) & the Stephan-Boltzmann Law (warm matter emits more IR than cold matter), then I won’t be able to explain this in a brief post here. This was the guts of a different post, which should explain this better ( https://tallbloke.wordpress.com/2012/12/06/tim-folkerts-simple-argument-supporting-a-radiative-greenhouse-effect/ ).
Tim Folkerts says: January 22, 2013 at 5:05 pm
“With all due respect……”
Look deeper into a ‘wet lapse rate’ and you may find the GHE that you were looking for in your link. 😉
CO2 has little ‘hidden’ energy. 🙂
Best regards, Ray.
Ray,
“The greenhouse effect” is a function of the lapse rate and of the IR properties. It is not one or the other. So no amount of looking at just ‘wet lapse rate’ or at just the IR properties will give people a full understanding.
Tim Folkerts says: January 23, 2013 at 8:24 pm
“Ray,
“The greenhouse effect” is a function of the lapse rate and of the IR properties. It is not one or the other. So no amount of looking at just ‘wet lapse rate’ or at just the IR properties will give people a full understanding.”
I concur! 🙂 So why discuss all the complexities of ‘spectral lines’, ‘depths to extinction’, ‘TOA’ and ‘thermal IR/spectral IR’ when these approaches need a ‘LBL’ (line by line) analysis that takes a super-computer to work through for a global analysis. It takes the ‘focus’ away from the ‘atmospheric hydro-cycle’, ‘ELR’ and ‘latent heat’. All LBL calculations are for a ‘DLR’ (dry lapse rate) anyhow, so what do they miss out on? GHE! They CAN’T model clouds, or the top of the ‘greenhouse’, (which is at ~the tropopause).
Why not treat Earth’s atmosphere as a ‘radiative interface’ that shows TOA from the ‘surface’ up to ‘~mid stratosphere’ (depending on the altitude that you understand doesn’t ‘re-heat/insulate’ the surface. Mark altitudes as ‘bands’ that represent the percentage of TOA for both ‘incoming’ and ‘out going’ radiation (including the surface). This’ll give people some idea of what goes where so they can continue to speculate a warming or cooling scenario and let the people that want to discuss the ‘validity’ of the ‘apportioned bands’ continue their discussions.
Oh, wait! Trenberth et al already did this. However, they were hampered by incomplete data (they have my sympathy) and produced a graphic that has come to be known as ‘The Cartoon’ in climate circles. It really does need to be depicted with ‘finer’ detail. Does this ‘dissuade’ others from this approach? Probably. 🙂
IMHO, we need to include the ‘entire’ atmospheric hydro-cycle (including clouds) to enable us to express the full function of the GHE.
BTW. My apology for evoking your response to a ‘rhetorical’ question by me! I need to remember to make my rhetoric more obvious and less ‘cryptic’. 😦 I guess I’m just getting too cynical in my old age.
Best regards, Ray.
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