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OK, I’ll drop that subject and deal directly with the subject of your blog post.
You state that:
“If the Earth’s atmospheric pressure is to contribute to the enhanced surface temperature, then that would mean that the atmosphere would need to continually provide energy to the surface. It could only do this through the conversion of gravitational potential energy to thermal energy. This would then require the continual contraction of the Earth’s atmosphere.”
This quote demonstrates that you’ve fundamentally misunderstood Ned Nikolov’s hypothesis. He’s not positing a raised surface T due to an ongoing gravitational collapse producing a compression, generating heat which is then lost to space.
Atmospheric pressure produces a density gradient; i.e. it forces there to be more air molecules per unit volume at lower altitude than at higher altitude. Denser air intercepts and absorbs more of the sunlight passing through it than less dense air, producing more molecular collisions and excitation. It therefore holds more kinetic energy.The more kinetic energy it holds the higher its temperature will be.
Now, a gas at a higher temperature will expand, thus reducing density, but note well that this is a much smaller secondary effect than the increase in density caused by gravitational compression. Thus the effect of the gravitational force on atmospheric mass is to create a gradient not only in pressure and density, but temperature too.
Since 70% of Earth’s surface is covered in a medium that Ray Pierrehumbert correctly points out has great difficulty in losing energy via IR, it has to lose energy via evaporation and conduction instead. However, as a triple whammy, increased pressure suppresses the rate of evaporation because it reduces wind velocities as well as increasing the BP and raising the surface temperature. The ocean has to rise in temperature to the point where it can lose energy as quickly from its 2D surface as quickly as it gains it from solar radiation in 3D. A higher surface air pressure makes that equilibrium temperature higher than it would be with a lower surface air pressure.
Tallbloke's Talkshop 
Waste of time. Ken is always right.
Short Succinct and Scientific.
That is one too many Ss for Ken Doll to deal with.
Watching Ken’s comments on JC’s blog he comes across as an arrogant know-it-all who simply will not consider he may be wrong about anything. I constantly look forward to seeing him and his ilk get taken down a peg or two. In fact there are days when that is all that gets me out of bed in the morning.
Ned’s theory is quite elegant and it makes sense. Unfortunately there are those who mis-characterize it as being a perpetual motion machine and so wrong when as you explain here it is a thermal gradient resulting from atmospheric density being able to utilise solar radiation increasingly as the density rises towards the surface.
Oh well, new ideas always struggle to be accepted, even briefly.
I think you are over egging the Ideal Gas Law. The density gradient is a pure function of gravity. The temperature at the surface is a pure function of the earths average solar insolation and SB balance.. The “greenhouse effect” is the ramp up of temperature, moving down to the earths surface, from the altitude of SB radiative balance.
You say
Atmospheric pressure produces a density gradient
and later
increase in density caused by gravitational compression.
and
Thus the effect of the gravitational force on atmospheric mass is to create a gradient not only in pressure and density, but temperature too.
These seem to me to be different
Is it
(1)gravity(g) > density(d) > pressure (p)> temperature(T)
> = causes
or
(2)g>p>d>T
or
(3)g> d,p and T all at the same time, according to the gas law.
I support (3)
as explained in this paper
Click to access 10.11648.j.earth.20170606.18.pdf
Density and pressure curves vs. altitude are the same.
http://www.digitaldutch.com/atmoscalc/graphs.htm
Good to read a mention of kinetic energy and pressure. Need to let people know this applies to all “greenhouse gas molecules” which will then emit photons over their specific radiation bands. For example CO2 molecules will be happily radiating over the 13 to 17 micron bands and helping to cool the atmosphere in their small way. Also note that slightly LESS THAN HALF that radiated energy will reach the surface. This will not warm the surface, just reduce the rate of surface cooling over that very specific low intensity band.
Is there not a place for including both theories side by side as complementary.
Yes there is a gravity gradient and yes more molecules produces more friction and heat.
Yes GHH molecules help catch and distribute this heat.
Hence an atmosphere with GHG as the only difference will retain more energy init, ie be hotter, than one withoutout though both need the density derived from gravity to exhibit this heat.
People who say only one or only the other have agendas, not science in mind
Sailboarder: The temperature at the surface is a pure function of the earths average solar insolation and SB balance.. The “greenhouse effect” is the ramp up of temperature, moving down to the earths surface, from the altitude of SB radiative balance.
Where’s the empirical measurement of this “altitude of SB radiative balance” of which you speak? It’s not just a hypothetical construct, is it?
Actually, Roger, all 3 are correct and not mutually exclusive. It depends on what at the moment in time is a driving factor. IF P1V1/T1 = P2V2/T2, then changing either P or V or T will cause a change in the other variables to maintain the same value of Entropy. PV=nRT goes to density.
It should go without saying but ALL of these gas laws are dependent upon GRAVITY and Entropy which are assumed to be constant, i.e. an existing potential variable/influence that doesn’t change for the purposes of making those calculations. You must have an acceleration (force) to give mass a weight to create a closed system of a planetary atmosphere. And you must have Entropy, i.e. energy to be transferred to cause the effect.
IF earth’s gravity were for the sake of argument doubled, what would be the effect on the same mass of air? It would affect the pressure? Yes or No? IF you assumed the volume stays the same (e.g. pressure at 100 km altitude of Venus is essentially the same as Earth), then T must what?
Tallbloke
I am not trying to funny, but the “the empirical measurement of the “altitude of SB radiative balance” is located at the exact same place as the “global average temperature”.
Both exist as an abstraction.
dscott: If gravity doubled (with no change in surface area), pressure per unit area would increase, volume would decrease. What would happen to surface T? What would happen to the lapse rate? Good questions.
Sailboarder: The global average temperature is abstracted (some would say tortured) from actual empirical measurements made by ground based thermometers and satellite MSUs. There is no equivalent set of measurements of the “altitude of SB radiative balance”. It’s a contrived hypothetical with no realistic possibility of being actually measured by any instruments we have or will have anytime soon.
ANother problematic measurement is the TOA energy balance, which is only known to within an error of around 8W/m^2, or around 3 times the size of the signal it’s supposed to be constraining.
Tallbloke
” There is no equivalent set of measurements”
True, and unless balloons are equipped and lofted all over the globe.. the variation would be large, yet the SB balance exists overall.
I don’t have a problem with the idea that in the end, thermodynamics rules and it is expressed in the Ideal Gas Law. The net change in temperature on the surface would be a result of average humidity changes(lapse rate, density) due to the CO2 increases altering the energy flows. The humidity changes would change the insolation. I don’t think we will ever measure or model the AGW separate from the larger noise in the system, as you suggest. IMO, it should be small to essentially non existent.
Sailboarder: The net change in temperature on the surface would be a result of average humidity changes(lapse rate, density) due to the CO2 increases…
Let me show you something you didn’t know about humidity up near the tropopause at the 300mb level where it actually makes a difference to something in radiative theory.
The Sun controls humidity where it matters, not CO2.
I disagree with Ned Nikolov’s hypothesis on the simple basis that it does not take into account where in a planet’s atmospheric gases or surface materials that solar radiation in initially absorbed.
On Earth almost all solar radiation is absorbed at the surface, so understanding solar thermal gain in the true surface materials of the planet is the first step in understanding the climate system on Earth. Ned and the establishment scientists ignore this step, which leads to the erroneous belief that Earth’s atmosphere is warming the surface of the planet, not cooling it.
I do agree with Tallblokes claim –
“The ocean has to rise in temperature to the point where it can lose energy as quickly from its 2D surface as quickly as it gains it from solar radiation in 3D.”
– as I have verified this claim via empirical experiment.
If we were to remove all atmospheric properties above the oceans excepting pressure and cloud albedo (ie: no conductive or evaporative cooling and no backradiation), the Sun alone would drive our oceans an average of around 335K, far higher than the 255K that is the foundation claim of establishment climate scientists. Just as in spacecraft thermal control, in studying climate on Earth, surface properties are critical.
For climate on Venus, things are very different. Most solar radiation is absorbed in the middle of an atmosphere exhibiting strong vertical convective circulation. Solar energy absorbed in mid atmosphere warms gases which are adiabatically heated when compressed to 90 bar on decent to the surface. However just as on Earth, vertical atmospheric circulation is driven by absorption of solar radiation below the level of energy loss by emission of LWIR from atmospheric gases.
There can be no “quick fix” mathematical model that solves for temperature distribution on differing planets where the solar thermal gain in the true surface and atmospheric materials is ignored.
Hi Konrad, nice to see you drop by. I’d still like to publish your experimental work if you ever get the time to collate the diagrams and text.
You said: There can be no “quick fix” mathematical model that solves for temperature distribution on differing planets
And yet Ned and Karl’s equation does a good job of resolving spherically averaged surface temperature on a number of widely varying celestial bodies. Their next paper will deal with equator-pole surface energy distribution under an atmosphere.
Tallbloke
“The Sun controls humidity where it matters, not CO2.”
Thanks.
I accept that heat movement is slowed slightly by our added CO2. To compensate, a slight amount more of water is evaporated, time shifting/spreading the daily vertical mass/energy transport. The surface temperature change imo must be trivial, due this negative feedback. CO2 can only be a miniscule control knob imo.
I don’t know what to make of the 300 mb humidity rise, following sun spots, other that to suggest it is consistent with the above. More insolation = more water vapor.
Random fluctuations or noise around a mean is inevitable, ie, the 8 watts/m2 you mentioned.
(IMO, without measuring heat flows, not temperature alone, on a minute by minute basis, worldwide, we have nothing to validate our models. At best we will model the big influences, ice ages, 1000 year, 600 year, maybe 60 year cycles. We should stop funding this CO2 wild goose chase).
Small point. Radiative gases DO ABSORB finite quantities of sunlight energy. For example CO2 absorbs over the 2.7 and 4.3 micron bands. Check out the peak temperature of those bands. This energy is mostly transferred kinetically to other atmospheric molecules, warming the air, and shielding the surface from a small portion of sunlight.
Richard111: more than a small portion. NASA estimates 20% or so.
Hah! So NASA confirms not all the sunlight reaches the surface!
I assume some of that energy is used in the production of ozone and 14CO2.
And still they claim that radiation from CO2 over the 13 to 17 micron bands warms the Earth’s surface. Again check out peak temperatures of those bands using Wien’s Law and you will find the 13 micron band peaks at 243K, -30C, the rest of the band is of course much cooler.
Not much surface warming potential there.
Konrad mentioned ‘the erroneous belief that Earth’s atmosphere is warming the surface of the planet, not cooling it’.
But the Moon with no atmosphere to speak of is cooler than the Earth?
The Earth and Moon each receive the same flux of solar radiation; the important difference is that the Moon doesn’t have an atmosphere to insulate its surface.
http://staff.diviner.ucla.edu/science.shtml
Is there any real doubt that temperature increases with pressure?
I thought we had a lapse rate of known size that demonstrates this.
Then there’s the gas laws.
PV=nRT
V is constant for modest time periods. As is n and R. Leaving, for short time periods:
P ~= T
where ~= is proportional. So at higher altitudes, lower pressure in the column, lower T.
Over geologic time, n, the number of atoms can change. Over solar cycles as UV shifts, V the volume taken up (atmospheric height) changes somewhat. R is a constant.
One could also point out a direct potential action of UV by changing atmospheric height thus V:
Sun cooled off, less UV, height lowered (per NASA data) so for V being initial large V and v being later smaller v:
Pv=nRT while holding n R and P as constants (surface pressure constant), says that lower v directly ought to lead to lower T or cooling somewhere in the gas column.
Im a layman, but in tallblokes explanation of kinetic energy I cant help wondering that if we treat the atmosphere as just a thinner surface (I,e, take the entire planets mass as a unit) then the densest part would be the surface, which would therefore have even more kinetic energy than the bottom of a dense atmosphere.
Thanks E.M. It is rather astonishing that people who profess to know abut physics have so much trouble grasping the simple fact that gases at higher pressures are also at higher temperatures, all else being equal. Ken is starting to fluster, threatening to censor my further comments. I’ve left him with this to chew on:
tallbloke says:
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March 14, 2018 at 6:50 am
ATTP: This is getting silly. If you include evaporation and thermals, as well as radiation, then the solar actually loses about 500W/m^2.
I assume you meant ‘ocean’ when you wrote ‘solar’.
If you look at Trenberth’s original energy budget diagram, you’ll see that the net IR flux represents a cooling of the surface, not a warming. 390 upwards, 324 downwards.
So this 66W/m^2 loss along with 102W/m^2 loss via evaporation/convection, equals the 168W/m^2 incoming solar radiation absorbed at the surface.
I hope you don’t think this is ‘misinformation’. It’s easily verifiable at many many websites.
Konrad says
On Earth almost all solar radiation is absorbed at the surface,
http://mpe.dimacs.rutgers.edu/images/climate-system-energy-balance
absorbed by surface 161 W/m^2
absorbed by atmosphere 78 W/m^2
total absorbed 239 W/m^2
78/239 = 0.33
atmosphere absorbs 33% of all energy absorbed
http://mpe.dimacs.rutgers.edu/images/climate-system-energy-balance
awww come on now Tallbloke, you know that was the typical misdirect by someone who knows they can’t win a counter argument to that paper. They just hare off in the wrong direction with lots of smoke, flashing lights, and bright shiny objects to distract the mouth breathers.
I personally found their paper shocking. Shocking in it’s thermo dynamics simplicity (along with good science data to back it up). Then there’s the application of Henry’s law to dissolved gases (CO2 in the oceans) plus a dozen other very, very ordinary science with some new wrinkles like cosmic rays and clouds and pretty soon there is little to zero AGW to deal with. Just nature and science.
But of course that way you’d lose hundreds of millions in grants and maybe have to get a real job.
This earlier thread looks relevant:
”Is there any real doubt that temperature increases with pressure?”
Yes there IS real doubt as weather station records indicate. Because surface density is not constant. Sometimes the data shows temperature increases with pressure increasing and sometimes temperature decreases with pressure increasing. To find the latest data use a google string similar to: monthly weather record las vegas
This found a site showing weekly and monthly chart of temperature and pressure at Las Vegas. Inspection of the data shows for the surface atm. there is real doubt that temperature increases with pressure as sometimes temperature goes down with increasing pressure for “modest time periods”.
An indication your assumption, at least for surface weather records, “V is constant for modest time periods. As is n and R” is not supported as recorded in the weather data.
Rice’s dogma goes back years. He did not like it when three years ago Paul Homewood started looking at the land surface temperature, launching a dogmatic counter-attack of his own. In an article on temperature homogenisation, in which he accurately portrayed standard reasons for adjustments, ATTP concluded
That is, if the data contradicts your beliefs (and I can point to multiple lines of evidence that strongly suggests ATTP’s viewpoints are extremely strong held and lop-sided) then you adjust it. In looking at a number of examples temperature data sets across the globe, I found that the principle assumption of temperature homogenisation – that nearby stations are exposed to almost the same climate signal and that thus the differences between nearby stations can be utilized to detect inhomogeneities – does not hold in many places. Therefore, homogenisation will not only eliminate temperature biases, but will also eliminate real variations in trends, whilst producing unstable results. As data is often homogenized a number of times, trends will become increasingly contaminated with the views of the compilers of the data sets. Maybe the data adjusters in the field are not quite so as ATTP, but they are mostly of the opinion that “the world is warming and humans are the cause of it.” I
My quote from ATTP is in a summary article.
The comments from ATTP are interesting in themselves, the first one appearing within about 30 minutes of my publishing the post.
Despite being an astrophysicist, Rice seems to clearly avoid any semblance of the scientific method.
There is quite a lot you can learn from ATTP by critically reading his blog – though I would only recommend it in small doses. His dogma on temperature homogenisation is an illustration of how not to evaluate an issue. When looking at issues ATTP looks at secondary opinion pieces, filtering them strongly through his own opinions. A proper evaluation of any area should relate opinions in the context of real-world evidence. It is like a historian evaluating primary evidence through light of highly opinionated history books.
I created a graphic to illustrate the method. You will find a similar line in many Guardian opinion pieces on climate change.
mbc – is that purple thing at the top a flying saucer / UFO? 😎
Oldbrew
I am found out! It is an alien invading spacecraft that sucks in the thoughts of denialists. Members of the climate consensus are immune from such alien powers, as they are too busy looking inwards and communing with the higher realities of climate models to be influenced by such forces.
[reply] of course 😀
Trick says:
March 14, 2018 at 5:34 pm
”Is there any real doubt that temperature increases with pressure?
Yes there IS real doubt as weather station records indicate”
Oh dear! surface weather stations record surface pressure, typically 1000mb.
Typical maximum variation in surface pressure is +/- 40mb about 4%.
Going to the 300mb altitude you are reducing air pressure to approximately ONE THIRD.
I would like to think we could agree that a change in air pressure by 1/3 is going to have a distinct effect upon temperature whereas a 4% change would likely be lost in the daily noise.
“It is rather astonishing that people who profess to know abut physics have so much trouble grasping the simple fact that gases at higher pressures are also at higher temperatures, all else being equal.”
Actually, that depends on what else specifically you are considering equal. For example (assuming ideal gases) …
* a high pressure cylinder of N2 and a low pressure cylinder of N2 sitting in a room (with ‘everything else equal’) will be the same temperature.
* a high pressure piston of gas that is allowed to expand as the piston moves out (with ‘everything else equal’) will get cooler than it was before.
* a high pressure container of gas that is allowed to freely expand into an empty space (with ‘everything else equal’) will stay the same temperature.
* the gas in a tall cylinder at thermodynamic equilibrium (with ‘everything else equal’) will be the same temperature at the bottom as at the top.
Statements like “all else being equal” can be much more subtle than they seem at first! The first example above is probably the most intuitive situation where ‘everything else besides pressure is equal’ — same gas and container size and elevation and surroundings — and yet the temperature is indeed the same for both!
”* a high pressure cylinder of N2 and a low pressure cylinder of N2 sitting in a room (with ‘everything else equal’) will be the same temperature.”
All else equal means the densities are equal, here they are not. P=density*R*T
”* a high pressure piston of gas that is allowed to expand as the piston moves out (with ‘everything else equal’) will get cooler than it was before.”
All else equal means the volumes are equal, here they are not.
”* a high pressure container of gas that is allowed to freely expand into an empty space (with ‘everything else equal’) will stay the same temperature.”
Yes, but all else equal means the volumes are equal, here they are not.
”* the gas in a tall cylinder at thermodynamic equilibrium (with ‘everything else equal’) will be the same temperature at the bottom as at the top.”
Only if there is no gravity field. Also, thermodynamic equilibrium cannot be obtained in this example unless you make your tall cylinder a universe to itself.
Trick, the point is that there are many equations for ideal gases. PV = nRT is just one of them. We could consider U = 3/2 nRT which is true for a monatomic ideal gas. If we keep internal energy constant, then T is constant, independent of pressure, density, or anything else. It’s all a question of what you want to keep constant. You are NOT keeping internal energy constant, so not ‘all else is constant’ in your scenarios. Certainly several important things are constant, but not everything!
“[Temperature in a tall cylinder of gas is constant] Only if there is no gravity field.
No — even in a gravity field, a gas in thermodynamic equilibrium will be uniform temperature. This is subtle, but if it were not true, then you could easily build a perpetual motion machine.
For what it’s worth, any atmosphere of any real planet will have a temperature gradient closely tied to the pressure gradient. This is because any real atmosphere is NOT in thermodynamic equilibrium — it is constantly heated from the bottom and cooled from the top.
”Trick, the point is that there are many equations for ideal gases.”
The point is if ideal gas density is constant then necessarily P ~ T. If density is not constant then not necessary for P ~ T.
”This is subtle, but if it were not true, then you could easily build a perpetual motion machine.”
It is not true and you cannot build a perpetual motion machine. Your column, as stated, can never reach max. entropy until the entire universe does. If you make your column a universe to itself then it can reach max. entropy and at that point the thermodynamic machine will stop.
Trick,
1) You are ARBITRARILY imposing the condition that DENSITY is part of what you are keeping constant. That is a fine choice. But you are simultaneously assuming that internal energy (and entropy and any number of other things) are NOT kept equal. I am simply pointing out that ‘all else being equal’ invariably means some things are NOT equal!
2) I know many people think that the adiabatic lapse rate is consistent with thermodynamic equilibrium. It is not. The ‘adiabatic’ part of the name means that heat flow is not allowed. Gas rises and cools — but is forbidden from exchanging heat. Forbidding heat flow excludes a system from approaching thermodynamic equilibrium. Convection (ie non-equilibrium) is what creates the adiabatic lapse rate.
3) Your main argument seems to be “since nothing ever fully reaches thermodynamic equilibrium, then I can safely ignore any parts of thermodynamics when it is convenient.” We can (either theoretically or practically) make any system arbitrarily close to thermodynamic equilibrium as we like. The problems with the perpetual motion machine continue even as we get arbitrarily close to equilibrium.
4) Specifically, different gases have different adiabatic lapse rates. So when the gases are in thermal equilibrium at the bottom of the columns (ie at the same temperature), they would not be in thermal equilibrium at the tops of the columns (ie at different temperatures). Any claim that a temperature difference would be maintained at equilibrium means a heat engine could run perpetually off the difference in temperature. QED
”You are ARBITRARILY imposing the condition that DENSITY is part of what you are keeping constant.”
No arbitrary imposition, ideal gas density is not an arbitrary variable when discussing how measured pressure and temperature vary in an Earthian weather record. P=density*R*T ideality holds to a very close approximation of reality in Earth lower atm. If density, R are held constant, only then can discuss P ~ T meaningfully for the atm.
”Your main argument seems to be “since nothing ever fully reaches thermodynamic equilibrium, then I can safely ignore any parts of thermodynamics when it is convenient.”
Not my words, those are Tim’s words. No real system in this universe ever does reach strict thermodynamic equilibrium; all real processes produce entropy. Although there are plenty of real steady state processes.
”Any claim that a temperature difference would be maintained at equilibrium means a heat engine could run perpetually off the difference in temperature.”
Cannot run perpetually off a T difference, any arbitrary heat engine will stop when the universe in which it exists reaches max. entropy. Anything that cannot go on forever, will stop.
Perhaps you are thinking of some different situation than I am, Trick
I claim the state of thermal equilibrium for a gas in a gravitational field is NOT the adiabatic lapse rate.
Proof by contradiction.
1) Assume that the adiabatic lapse rate IS the thermal equilibrium state.
2) Get two columns of different gases.
3) Different gases have different adiabatic lapse rates.
4) Let the bottoms of the columns be in equilibrium with each other. (for example, put them in contact until no heat flow
5) Let the tops of the columns be in equilibrium with the bottoms. (for example, insulate the columns and wait until there is no movement of gas or energy within the columns).
6) This implies the tops are in equilibrium with each other.
7) Since the lapse rates are different, the temperatures at the top are different
6 & 7 contradict each other — two adjacent objects cannot be in thermal equilibrium and also be different temperatures. So SOMETHING is wrong above. 2,4,5 are simply stating the conditions of the situation. 3 is a well-known property of the adiabatic lapse rate. 6 is a consequence of the Zeroth Law. 7 is a consequence of 3 & 4.
Unless you can point out something I missed here (and please be specific), the only thing left is that (1) is wrong.
”Unless you can point out something I missed here (and please be specific)”
You miss: 1) is wrong assumption, DALR is not max. entropy if you mean by thermal equilibrium thermodynamic internal equilibrium (thermal is a shortened form for therm-odynamic intern-al)
You miss: 2) whether each column is perfectly isolated from surroundings
3) is correct as Cp is different, 4), 5) you miss that you then redefine initial setups i.e. you change the problem so that 6,7 contradict each other at least initially i.e. you add entropy to the initial setups in 2).
Trick says: “You miss: 1) is wrong assumption, DALR is not max. entropy”
Actually, that was the point — DALR cannot be max entropy because it leads to the contradiction at the end. The actual equilibrium condition (ie max entropy) is isothermal.
“The actual equilibrium condition (ie max entropy) is isothermal.”
Tim, isothermal T(z) = constant is lower entropy than the Poisson T(z) for an isolated ideal gas column in a gravity field so isothermal cannot be max. entropy thermodynamic equilibrium. Try your 1-7 assuming Poisson T(z) in 1) and make the columns isolated. Thinking them through that way will help.
Are you talking about “potential temperature”? Suggesting that a gas column that has a gradient equal to the potential temperature is the max entropy state = equilibrium state?
Do you have a reference to back up that claim?
Yes, defining eqn. for potential temperature is part of the solution for max. entropy in isolated ideal gas column. Ref. is introductory atm. thermo. text Bohren 1998 Chapter 4.4.
Use that work for your 1), then in 2) make the columns isolated. Use 3) as is, think though where 4), 5) take you then connect the top and bottoms and just think through what happens, the calculations for combining R1, R2 ideal gas would be straightforward but too complex for here.
@oldbrew
Sorry for the slow response. You asked:
“But the Moon with no atmosphere to speak of is cooler than the Earth?”
The answer is very simple: Surface properties are everything!
71% of this planet’s surface is liquid salt water. Solar thermal gain in water over 200m deep is very different from solar thermal gain in the sharp edged vacuum insulated basalt grains of the lunar regolyth.
Here’s a simplified PDF on spacecraft thermal control:
Click to access Satellite_TC.pdf
Laugh at slide #25. (That one’s there to amuse engineering students).
Now look at slide 53. For equal solar illumination, differing materials reach very different equilibrium temperatures. Surface properties are everything!
But those figures are just for solar opaque materials. It gets far more complex for solar translucent solids and far more complex again for solar translucent liquids. Now add an intermittent cycle of solar illumination. You can’t solve for solar thermal gain in the oceans using instantaneous radiative balance equations like the S-B equation. Only CFD or empirical experiment can solve for these conditions. Climastrologists provably used neither in formulating their crazed foundation claim: “surface Tav of 255K without radiative atmosphere”.
Trick, I strongly suspect that your textbook does not say what you think it does.
We are not going to work it out here, but let me give you once simple thing to ponder. Pretty universally, as systems head toward thermodynamic equilibrium, they ‘settle’ down toward the lowest elevation they can reach. (For example, ball bouncing around in a room settles to the floor and stops moving).
For a gas, the center of mass will settle if the bottom cools and the top warms (so the bottom gets more dense). A gas that follows the adiabatic lapse rate is the REVERSE of this, with warm, low density gas at the bottom. The gas can ‘settle’ by cooling at the bottom. Of course, it can’t cool any further than isothermal. (Certainly this is not a ‘proof’, but it is highly suggestive.)
Tim, you are debating with an energy minimization argument (Hamiltonian) when entropy maximization is the subject. On p. 167 ed. 1 just after proving max. entropy T(z), Bohren asks the reader: “Why isn’t the equilibrium profile isothermal?” So, there is a text book answer for you should you choose to dig in deeper.
Trick, there are also several textbook answers that say the profile should be isothermal.
I just googled a bit and found several sources that talk about the “equilibrium” solution being non-isothermal. However, careful reading of ALL of them shows they actually mean “steady-state”, not true “thermodynamic equilibrium”. I will bet 10:1 that is what your source says if your read closely.
Remember, true thermodynamic equilibrium means no net energy flows within the systems, and no energy flows to/from outside the system. Any discussion of “radiative equilibrium” is about (energy flows in) = (energy flow out). This is — by definition — NOT true thermodynamic equilibrium.
[It’s much like putting a cool pan on a warm stove-top and waiting for the pan to come to “equilibrium” at some new, higher temperature. That is NOT “thermodynamic equilibrium”; that is “thermodynamic steady-state”. Energy is constantly entering the pan from the heating element, moving through the metal, and exiting to the room. But colloquially (and clearly even in many textbooks), ‘equilibrium’ is used in place of the more technically correct “steady-state”. ]
Also … entropy is a measure of the randomness of energy. The more randomly the energy is distributed, the higher the entropy. Initially, a lot kinetic and potential energy was concentrated non-randomly in the ball (in my previous example), but eventually the energy gets spread out as thermal energy in the walls and floor of the room. Random thermal energy never leaves the floor and spontaneously concentrates back into the ball to increase the KE or PE. Similarly, in an isothermal column, potential energy is low. To create a lapse rate, more and more energy gets concentrated into potential energy, which is not how nature tends to work. This sort of concentrated, non-random energy is exactly the sort of thing the 2nd Law says cannot happen in a disordered system.
”I just googled a bit and found several sources that talk about the “equilibrium” solution being non-isothermal”
Links?
Maximum entropy being obtained and proved for an isolated system (a universe to itself) means there are no further net energy flows within the systems, and no energy flows to/from outside the system as that would produce entropy. So Bohren’s entropy maximization proof meets your def. of true thermodynamic equilibrium. No further entropy can be produced in the universe at that point.
Here’s another intuitive argument I just saw. If the gas in the column were CO2 and if there were a temperature gradient, then there would be a net flow of energy up the column in the form of thermal IR. By definition, such a system is not it thermodynamic equilibrium. Such a flow of thermal IR would continue until the temperature became isothermal. If the temperature NEVER became isothermal, then the internal flow would never stop!
“If the temperature NEVER became isothermal, then the internal flow would never stop!”
By 1LOT. By 2LOT, if that column is isolated, the net energy flows continue until max. entropy and no further net energy flow is possible at that point & stops as any further net energy flow would increase entropy. This is one of the reasons the 2LOT needed to be invented.
Bohren mentions this and writes you are letting intuition of conduction in a solid interfere with thinking about net energy flow in a gas. You really need to get a copy of the text, should be easy at your local college library for free.
“if that column is isolated, the net energy flows continue until max. entropy”
Exactly. Are we talking past each other??
Net energy continues to flow (in the form of thermal IR) as long as the bottom is warmer and the top is cooler. Hence any situation where the bottom is warm and the top is cool has not reached max entropy.
Only when the top and bottom are the same temperature will this flow of energy stop. Only when the top and bottom are the same temperature is no further net thermal IR energy flow possible and only at that point is max entropy reached. This seems to be using exactly your words and line of reasoning.
”Only when the top and bottom are the same temperature will this flow of energy stop.”
No, compute the entropy in isothermal profile. It will be lower than computed for the T(z) found from Bohren’s max. entropy T profile, thus isothermal T(z) continues to produce entropy in this universe until it reaches the T profile for the max. entropy and all net energy flows then stop. Don’t know how many times I have to write this. Read the text.
Trick — I am just using your ideas and the most basic of syllogisms:
If P then Q
P
Therefore Q
If (there are net energy flows) then (not max entropy)
(there are net energy flows) [thermal IR from bottom to top]
Therefore ….
In 2012 when the Nikolov and Zeller hypothesis debate raged, I did a simple empirical experiment which Roger kindly published.
All I did was put two identical matt black solar targets in two identical pressure vessels. I included a solar shielded thermocouple in each vessel to measure air temperature. The only difference between the vessels was one was held at 1.0 Bar and the second at 1.25 Bar. On solar illumination the air temperature rose faster and higher in the higher pressure vessel. The answer is simple: there were more air molecules in conductive contact with the solar illuminated surface.
Atmospheric pressure plays a critical role in atmospheric temperature, but instantaneous linear equations can never solve for it. This is why Sir George Simpson of the Royal Meteorological Society warned Callendar in 1938 –
“..but he would like to mention a few points which Mr. Callendar might wish to reconsider. In the first place he thought it was not sufficiently realised by non-meteorologists who came for the first time to help the Society in its study, that it was impossible to solve the problem of the temperature distribution in the atmosphere by working out the radiation. The atmosphere was not in a state of radiative equilibrium, and it also received heat by transfer from one part to another. In the second place, one had to remember that the temperature distribution in the atmosphere was determined almost entirely by the movement of the air up and down. This forced the atmosphere into a temperature distribution which was quite out of balance with the radiation. One could not, therefore, calculate the effect of changing any one factor in the atmosphere..”
If Sir George Simpson were alive today, we may not be drowning in the pseudo-science of the AGW conjecture …
“(there are net energy flows) [thermal IR from bottom to top]
Therefore ….”
Therefore Tim is wrong, as at max. entropy point there can be no net energy flows in the gas column universe. Bohren explains why on p. 167, read the text.
I see that Mr Rice has now added a post on his Forum “Moderation”.
It appears someone might have upset him just a tad.
You keep saying I must be wrong. Are you saying energy in the form of thermal IR does NOT flow from warm areas to cool areas? That if there is a column of CO2 that is warm at the bottom and cool at the top, that thermal IR just decides not to obey the Stefan-Boltzmann law? If the same column was sideways, would IR energy flow then?
”Are you saying energy in the form of thermal IR does NOT flow from warm areas to cool areas?”
As in a solid? No, but yes for a gas universe. Tim, again, your repeated responses make it clear I am not a source to you for the answers you seek. I urge you to get a copy of Bohren’s 1998 work and read the detail of the subject general proof.
But if you want to discuss with me anyway, realize first at max. entropy point in the isolated ideal gas column in a gravity field there is no longer any thermodynamic free energy. Thus, net energy cannot “flow” any longer. Again, p. 167 Bohren answers your question that he also poses: “Why isn’t the equilibrium profile isothermal?”
When you pose reasoning for any other answer something must be wrong. You seem to be insistent that thermodynamic energy can flow in this gas universe at max. entropy. This is wrong, processes that produce entropy can’t be at work, and I’ll continue to point that out. Again, read the text, you won’t ever agree with me without doing so as I’d have to write about 10 pages of text & that without the foundation already built.
manicbeancounter says:
March 14, 2018 at 9:31 pm
Rice’s dogma goes back years. He did not like it when three years ago Paul Homewood started looking at the land surface temperature, launching a dogmatic counter-attack of his own. In an article on temperature homogenisation, in which he accurately portrayed standard reasons for adjustments, ATTP concluded
What if there isn’t a full record, or you can’t find any reason why the data may have been influenced by something non-climatic? Do you just leave it as is? Well, no, that would be silly. We don’t know of any climatic influence that can suddenly cause typical temperatures at a given location to suddenly increase or decrease. It’s much more likely that something non-climatic has influenced the data and, hence, the sensible thing to do is to adjust it to make the data continuous.
Uhm, I do, it’s called a cloudy day, on any given spot, every passing cloud will temporarily block the sun lowering the air temperature until it passes then the sun comes out raising the temperature just like a switch… /sarcasm/
It’s well documented in meteorology that sudden radical temperature swings do occur.
Heat Burst: http://www.crh.noaa.gov/oun/?n=heatburst_info 10 to 15 F rapid increase
5 Incredible Temperature Swings – 49 Degree Change in Two Minutes
Spearfish, S.D.
https://weather.com/sports-recreation/ski/news/5-extreme-temperature-drops-20130118#/1 You can click for the other dramatic temperature swings at the bottom of the link.
In other words by discounting actual acts of nature that typically perturb the temperature, they substitute their estimates thus corrupting the data.
ATTP claims: ‘We don’t know of any climatic influence that can suddenly cause typical temperatures at a given location to suddenly increase or decrease.’
Try wind. Any wind will do but…
Föhn winds can raise temperatures by as much as 14 °C (25 °F) in just a matter of minutes.
http://en.wikipedia.org/wiki/Foehn_wind
I’ve experienced it myself. Weather went from hot and sunny to thunderstorm with hail in about 20 minutes.
(That was the sudden end of the Föhn).