Guest post from ‘Lucy Skywalker’.
Last time I described my visit to Roderich Graeff’s seminar. Now we look at the experiments in detail. Experiment trumps theory. Experiment is the final arbiter, as Einstein said. Only after looking at the experiments do I want to consider the theoretical elements.
HISTORY AND CONTEXT
One has to be aware of the depth to which the Second Law has been held most sacrosanct of all the laws of physics. Eddington said famously:
“If someone points out to you that your pet theory of the universe is in disagreement with Maxwell’s equations—then so much the worse for Maxwell’s equations. If it is found to be contradicted by observation—well these experimentalists do bungle things sometimes. But if your theory is found to be against the second law of thermodynamics I can give you no hope; there is nothing for it but to collapse in deepest humiliation.”
But today, Dan Sheehan of the University of San Diego could write in his 2005 book “Challenges to The Second Law of Thermodynamics“:
“The second law has no general theoretical proof. Except perhaps for a few idealized cases like the dilute idal gas, its absolute status rests squarely on empirical evidence. As remarked by Fermi and echoed by others, “support for this law consists mainly in the failure of all efforts that have been made to construct a perpetuum mobile of the second kind”… [yet] One would be hard-pressed to name ANY physics theory, concept, law or principle that has not undergone major revision either in content or interpretation over the last hundred years… The damning question is, why has it taken so long for [the 2LoT’s] absolute status to be questioned?”
Dan Sheehan thought it worthwhile to visit Graeff at home and see his experiments. Graeff’s unique challenge is backed by years of engineering-quality experimental work. His apparatus can hardly be thought of as a perpetual motion machine. And his challenge is not to the essence of the Second Law, but a modification needed to one of its commonly supposed consequences, namely, the believed equality of temperature between top and bottom of a column of air in equilibrium. Unbelievably, until Graeff, nobody actually tested this supposition. Graeff’s results, at laboratory scale, are tiny but are highly consistent, significant, and replicable. But perhaps even twenty years ago such results could not have been detected.
Graeff presented an excellent paper at Sheehan’s 2011 conference, that is well worth perusing. He noted wryly that he was the only one at Sheehan’s conference who had actually done experiments. This is from his introduction to his paper:
“It is known that temperature gradients in gases and liquids are stable only up to the adiabatic lapse rate… In order to make greater values possible, the author tried various convection-suppressing designs. It was found that the use of fine powders like glass powder largely eliminated convection currents. This has the added advantage of preventing any heat exchange by radiation within the test setup.
“The basic setup consists of an elongated container in a vertical position, with volume varying from ½ liter up to 2 liters, and height varying from 15 cm up to 100 cm. This container is highly insulated from the environment… The temperature gradient T(Gr) of the inner axis is measured with thermocouples, arranged as a thermopile.”
TWO CLASSIC EXPERIMENTS
This is the setup for the 2007 water experiment B372, from the paper already discussed on this blog, with colouring added for clarity. Pinks are insulating layers; greens are thermal-equalizing layers (metal, water jacket). The core (1-5) is not drawn to scale: it is narrower and taller. Read the details of experiment B372 further down.
TESTING AIR: B74 (from website)
When planning the initial experiments in 1998, Graeff did not know what to expect. If there was a temperature difference, it would be a very small one, as otherwise somebody would have measured it long ago. But was it 0.01 K/meter of height, or 0.001 or only 0.0001K/m?
He settled very quickly on the use of thermocouples to measure the temperature difference. Thermocouples don’t introduce any energy into the experiment. They cannot create temperature differences. Just the opposite in fact.
For measuring the voltage produced by the thermocouple he selected a multimeter with a resolution of 0.1 microvolt, which, dependent on the type of thermocouple selected, would have a resolution of about 0.003 K.
The most difficult task is to insulate the actual experiment from the temperature influences in the space around it. Rooms typically have a temperature gradient of +1K/meter of height, warmer at the top. Temperatures fluctuate from day to night, from winter to summer. How can one expect to measure meaningful temperature differences of a few thousandths of a degree if the outside temperatures show fluctuations more than 100 times as great?
This picture shows the setup. A Dewar insert of a commercial Thermos bottle (1) was mounted within a wide mouth Dewar insert of 1 liter size (2) which was covered by a similar Dewar insert of 1/2 liter (3). The space (4) between the innermost Dewar and the two outside Dewar inserts was filled with fine PET fibers.
The innermost Dewar (1) of 1/2 litre was filled with a fine powder in order to eliminate convection currents and radiation between the inner wall surfaces. A thermocouple (5) was arranged vertically in the middle axis with a distance between junctions of 170 mm. A second thermocouple (6) was taped to the outside of the Dewar insert (1) with a vertical distance of 180 mm. A third thermocouple (7) was taped to the outside of Dewar insert 2 with a vertical distance of 230 mm.
The Dewar inserts were held in place by fine PET fibers within a box (8) fabricated out of 40 mm thick polystyrene foam panels. This box was surrounded by 50 mm thick panels (9) consisting of copper wires pressed together into rectangular blocks. The whole setup was insulated from the air in the room by 100 mm thick polystyrene foam panels (10).
The diameter of the thermocouple wire is kept as small as possible in order to reduce any heat conduction through these wires. The measuring instrument measures the voltage of the thermocouple with a resolution of 0.001K.
TEST RESULTS OF B74:
The temperature differences shown by the three thermocouples were recorded every 4 minutes over a period of half a year. In this graph, each point represents the average of 60 measurements over a 4 hour time span.
Any point above the zero line means that the upper junction of the thermocouple is warmer than the lower junction.
It can easily be seen that the temperature difference on the outside of Dewar insert 2 is quite constant and always warmer at the upper junction than at the lower one by about .045K. This is the result of the temperature gradient in the surrounding room air, which is warmer at the top and cooler at the bottom, typically by 1K/m of height. The insulation around the Dewar inserts, and especially the thermal equalizing effect of the thick copper plates, are why this gradient for the Dewar inserts is so low.
An opposite effect can be seen at the inner axis, where most of the time the temperature of the upper junction is lower than the lower one.
This result is more clearly demonstrated in the following graph. Each point represents the average of all values from the beginning of the test up to that point [date].This cumulative calculating procedure shows a clear average steadily emerging from noisy data:
The middle axis shows, on average, a negative temperature gradient, cooler at the top and warmer at the bottom, that cannot be explained by applying the normal formulas for the conduction of heat. Under these laws, heat can travel only from an area with a higher temperature to an area with a lower temperature. The value of the inner axis of -0.0705 is surprisingly close to the theoretical calculated value of -0.07. One would expect a measured value somewhat closer to that of the surrounding gradients, and certainly not one in opposition to them.
Both calculation and explanation require consideration of the effect of gravity on the molecules in the innermost space of Dewar insert 1, translating kinetic energy acquired into heat transported from top to bottom. Only one of the degrees of freedom is affected by gravity, and therefore the normal specific heat must be divided by the number of degrees of freedom involved, to calculate the theoretical temperature gradient. Normally this gradient is lessened by convection in the atmosphere, and seems to be completely neutralized by convection in the oceans – thankfully, otherwise the planet would be uninhabitable like Venus.
TESTING WATER: B372 (from Graeff’s paper). See setup diagram higher up.
The temperatures inside the test setup are measured by thermocouples and by thermistors. These are mounted at the tops and at the bottoms of the inner axes of the two glass tubes. Additional sensors are mounted on the outside of these glass tubes and on the outside of the two PVC tubes. The temperatures of the double wall aluminum housing are measured 3 cm below the top and above the bottom.
The test setup was installed in May 2006. All sensors were connected to DMM Multimeter Keithley model 2700 and the data fed into a computer. Measurement results are reported from December 2006 through March 2007, a time period long after the setup, so that it can be expected that equilibrium conditions had been reached.
WATER TEST RESULTS
Caveat:: I’m waiting for Graeff to say whether the numbers 9-14 below are correctly allocated.
Each point of the curve represents a 10 value average (of a ten times repeated reading of the same object) measured every hour, using the scale on the left side of the graph. The smooth lines represent the thermistor measurements, each value measured hourly in centigrade, using the scale on the right side.
This graph yields many secrets. First, see how far the convection-inhibited water (1) depresses the negative temperature gradient. (1) is firmly negative. (6) and (7) are firmly close to zero. (8) is firmly positive. By the standard interpretation of the Second Law there should be nothing at all in the blue section. The “free” water (2) also shows a negative gradient, but far closer to zero, and to its PVC casing. Has it simply picked up the gradient of the convection-inhibited water? Plus that of the surrounding convection-inhibited air in the lagging? Now see how steady the results are holding There are no wild flickers as with the air experiment (B74). This is because thermal capacity is far higher so the experiment is more robust to external fluctuations. All the dots connect coherently into sets of lines that run parallel, so we can trust that something is being measured reliably. And what a fine scale – this is because they are 10x more sensitive to gradient than to absolute temperature. Yet the thermistors also give very steady curves, running parallel showing they too are measuring coherent values. See how the gradients all together blip up shortly after the temperature stops falling and starts rising? Conversely, all the gradients dip down shortly after the temperature stops rising and starts falling. Why? Evidence suggests that the top of the core is affected by external temperature changes before the bottom of the core is affected. The thin lines in mid-January indicate a nonfunctioning datalogger for that period – but results are not affected.
The paper on B372 has two more graphs which are worth revisiting: it is vital to appreciate the precision of work here, and how it has been possible to extract further precision through cunning application of statistics. The question still needs to be asked: why is this measured gradient a tiny bit larger than the calculated gradient? But even this question cannot take away the fact of a negative gradient surrounded by a positive-gradient environment.
THEORY
We will elaborate on the theory next time. For now, it is important to establish the validity and importance of the experiments. Until Climate Science with Santer, Trenberth, and others, the primary importance of significant “rogue” data, either from experiment or from observations, has always been the case with Science. Almost always, theories have followed data discoveries; the existence of theory-less data is not an indication of bad science, in fact quite the opposite. This should not need to be said, but I have seen too many scientists claiming in effect that without a theory, the data does not constitute Science.
Meanwhile, for those already interested, there are calculations, with theory explained more or less, here and here. Graeff’s book contains two chapters I regard as important, which explain nicely his own journey to understanding, and how his building of theory happened.
OTHER EXPERIMENTS
Graeff had a drum made from thick aluminium cylinders, with inner and outer containers capable of revolving separately, very slowly. First he rotated the outer drum, to provide an external environment with a much more constant temperature – only to prove that this did not materially affect his essential core results anyway. He then rotated the inner drum with the tests, and showed that about a day after inversion, the negative temperature gradient would reestablish itself. Here it is difficult to explain these results by anything other than gravity.
Graeff has tested metals and other materials like oil. Xenon testing is hoped but difficult. Prof Chuanping Liao has done interesting tests including using a centrifuge. But as Graeff says:
“These results are only meaningful as long as the environment shows a positive gradient, opposite to the negative gradient measured for the inner axis. This question Prof. Chuanping Liao does not discuss in his paper”.
Some mention is made of Graeff’s range of experiments in his 2011 paper. The experiments are ongoing and more has been tested since then. Graeff will now say that whereas he would have had doubts earlier that his experimental results could be flukes or have some non-gravity explanation, he cannot really assert this any longer, in the wake of his hundreds of experiments containing data that is both statistically significant and well-tested for experimental bias.
WHAT NEXT?
I am planning another post to look at Graeff’s theoretical work, and to discuss my plans for replication. I thought I could do both these in this post, but I see we will overload, and important insights and directions for discussion will be neglected. IMHO Graeff has worked out all the theory we need, in a straightforward way and with a delightfully human touch.
I am hoping to return to Graeff in the Black Forest presently with a small group, to apprise ourselves of exactly what we need for replication, to discuss what we should focus on, and how to get the word out where it needs to go ie universities. This will also be an excellent opportunity to learn to work together as a team.
My mind is in some ways quite simple and my scientific virtuosity is sometimes limited, and I really don’t want to get any more complicated than we need. I am focussed above all on restoring integrity to Climate Science, and by extension, to Science in general again – and to open up the field to participation with amateurs, as was always originally the case. I have tried to tackle one issue at a time, with enough thoroughness and politeness so that like Steve McIntyre we can work towards stopping all back exits to the current levels of slovenliness, bias, corruption and stupidity.
To me, it is plain that this experimental challenge of Graeff’s is highly important, both to Science in general, and to Climate Science in particular. I personally am also concerned that this important work has so far not been accorded the status of reposting at blogs like WUWT. I’m aware of course that problems arose over Willis’ perception of Joel Shore’s treatment here, and over widespread dismissal of Nikolov and Zeller that was largely because of their alleged flouting of the Second Law. So after explaining Graeff’s theory, I propose to write an article on Science By Blog, effectively Experimentum Summas Iudex part 3, with reference also to some familiar issues of “Freedom of Speech.”
For now, I ask commenters to stick with the overall message of this post as far as you can please! I think it is important that we take one step at a time, and validate the experiments first, before proceeding to theory and thence to the questions of getting a fair hearing, both on the climate skeptics’ blogs and in the universities’ research departments.
Tallbloke's Talkshop 
Rog that was quicker than I expected, thanks! I trust you will upload Graeff’s 2011 paper and hyperlink it to my piece as described in my latest email ie (a) between pics 1 & 2 (b) in the THEORY section first “here” of “here and here”. It’s a good paper.
Done! 🙂
The water experiment graph has some figures on it which I am still checking with Graeff, his email was refusing attachments so I’m emailing him telling him he can now see it here.
Lucy – Fine top post, thx.
Top post: “The innermost Dewar (1) of 1/2 litre was filled with a fine powder in order to eliminate convection currents and radiation between the inner wall surfaces.”
Q1s: Filled w/powder? Whoa. How am I to interpret? Can you add more details on the fine powder amount/type? This says “filled” with no mention of any filling w/air. I assume air is in there too, ha. Where did the air come from & what was the initial T&P profile? Room temp.? Mass of air? Mass of powder?
Q2: Where there any experiments w/o any fine powder at all to investigate any difference?
Q3: Items 6 & 7 not shown in figure for B74?
It is very likely that the experiment does not violate the 2nd law. Rather that the 2nd law was misapplied to conclude that no such gradient would appear. 150 years later, we finally have the equipment sensitive enough to check.
The gradient cannot exist without an external energy source. Any engine that makes use of the gradient is simply drawing energy from the external source.
For example, with an engine shut off, the gradient would maximize. As the engine ran, the gradient would decrease and as it did the efficiency of the engine would decrease until it stopped. At which point the gradient would increase and the cycle repeat.
The energy to create the gradient comes from outside the container, be it the conversion of molecular potential energy to kinetic energy by gravity, or some other process. Without an external energy supply there would be no gradient.
ferd berple 9:59pm: “The energy to create the gradient comes from outside the container, be it the conversion of molecular potential energy to kinetic energy by gravity, or some other process. Without an external energy supply there would be no gradient.”
This is correct (except it is an external force supplied) from recent theory advances over classical soln.: if the force of gravity crosses into the control volume and creates the f * dz energy, then get a theoretical gradient in air & non-isothermal (cooler at top), isentropic at LTE if constraints are like Graeff’s closed dewar.
If no gravity under same constraints, then no gradient & find isothermal LTE air in same dewar. Just turn on gravity again somehow, the g force then supplies the molecules f *dz energy & get non-isothermal gradient at LTE.
Trick, thanks.
Q1: The “fine powder” is almost certainly glass powder. I’ve seen the stuff and it flows around when you handle it like a liquid. I’m not totally sure if the spheres are hollow too, in this case, but it certainly seems the particles are spherical and same-size, so that there is air in the interstices. It’s difficult to slow air down without using some kind of substance, and yes this substance is not air and will therefore likely affect the reading! I believe Graeff actually tried many different impeders and generally settled for this “glass powder”. And for whatever reason, the measured data for air are remarkably close to the theoretical calculations (see links for these, or wait for next instalment).
Yes, air at STP, nothing filtered out. He’s still trying to work out how to test xenon satisfactorily. Graeff’s experiments have reminded me that it is pretty well impossible to exclude all irrelevant material, yet the whole of Science has advanced on experiments that were able (often only just able) to achieve results despite such limitations.
The gradient measured is Kelvins per metre so actually ambient temperature and pressure don’t actually matter, and the water experiment shows the gradient holding very steady even when the ambient temperature changes.
Q2: Control experiment? It seems to me, the atmosphere outside is such – where we find the adiabatic lapse rate which is characteristically less than Graeff’s convection-impeded rate.
Q3: I guess the items 6 & 7 that you refer to, must belong to the diagram for the WATER experiment. I put that picture a bit out of place, it really belongs lower down together with the water graph but I reckoned it would be good to start with a picture that is probably already familiar to readers here, from prior exposure to the water experiment.
The AIR experiment was a much earlier and actually cruder experiment. But its results are simple to see, and telling. At that stage, Graeff did not trust thermistors not to inject spurious heating into the experiment, for example.
More tomorrow, I’m tired tonight!
For Trick esp.
Q4 (my own): I wonder about all components affecting each other. I wonder whether, in the water experiment in particular, the “free convection” water tube is affected by gravity effects in (a) the glass of the tube (b) the surrounding “impeded convection air” of the insulation (c) the nearby “impeded convection” water. What is important too is that they are all in a near-zero-gradient container. But the “free water” shows at least some negative gradient, whereas oceans do not. And the most important thing is the clear presence of the negative gradient that “should not” be there.
Memo to myself to ask Graeff.
I feel that Graeff’s experiments are very interesting, particularly due to the counter intuitive results from what temperature profiles occur in liquids in which convective stratification occurs. I am not sure hoverer that this is directly applicable to the N&Z hypothesis. The N&Z hypothesis as I see it is simply that the conductive transfer of energy from a heated surface to a gas in contact with it increases with the density of the gas.
Graeff’s experiments seem to be dealing with another effect, with hotter molecules in a closed container acting as if they were heavier than cooler molecules when normal convective flow is restricted. This may be due to the speed at which individual molecules or individual electrons in those molecules are actually moving. It is claimed that as matter approaches relativistic speeds, its apparent mass increases. What speeds are individual molecules or their electrons moving at?
Lucy 12:53am – I’ve run into this fine glass powder – hollow glass beads. One use is to mix them w/epoxy to repair dings in fiberglass gliders/airplane wings b/c they are so light. Also used as filler paste between foam blocks. Why did Graeff need the “impedes” at all? I haven’t found time to read his stuff.
You didn’t mention to what extent the beads “fill” the dewar. And I do mean 6,7 missing from the air dewar diagram, count the left side numbers see two are missing.
I will not be able to contribute much informed discussion on the water experiment; I’m just tuned up on ideal gas nature.
Trick asked:
Why did Graeff need the “impedes” at all?
To mnimize convection.
If convection were allowed to occur, the lapse rate would be limited to the Dry Adiabatic Lapse Rate. With this design, convection is limited to turbulence in the space between the beads, or maybe inside the beads.
That does raise the question of whether or not the beads in water were hollow, and if the water filled the beads or if they remained filled with something else.
Trick 1:54am – thanks for confirming what I suspected that the “fine powder” is actually hollow glass spherules. He is testing convection-impeded air here, otherwise he might just as well refer to the wellknown adiabatic lapse rate. I know he tried various things to impede convection and found these spherules best. And the fact that they have air inside them means that the addition of glass to the vertical column being tested, is more minimal. It would be good, in the fullness of time, to know the exact proportion of glass to air but it’s still a secondary matter to the very presence of the negative gradient.
How full is the Dewar? Enough to cover the thermocouple, I guess, plus a little extra. I don’t know any more exactly than that, but of course, this is something that we can keep tabs on if/when we replicate. Again it seems to be not of primary importance.
Missing numbers? I see you are right, and will try to get this corrected. They are there in Graeff’s original sketch used, but I spliced text from here with improved pic from here
Glass beads used in water convection impedance… were these also hollow? and whether hollow or not, I think their composition might affect the water results… possibly (if hollow glass spherules were used) a significant contribution from the AIR gravity temperature gradient would raise the gradient measured.
Theoretically, air has a gradient of 0.07K/m while water’s gradient is 0.04K/m yet the measured “water” gradient is 0.05 K/m. I suspect one could calculate how the overall effect must have been partitioned between air, glass and water… and discover that THIS total, calculated theoretically, would match the result gained in practice, even more closely.
Aaaaah, thanks Trick and Q Daniels. That might be a good starting-point for another experiment….
Konrad: I feel that Graeff’s experiments are very interesting… I am not sure hoverer that this is directly applicable to the N&Z hypothesis. The N&Z hypothesis as I see it is simply that the conductive transfer of energy from a heated surface to a gas in contact with it increases with the density of the gas.
Graeff’s experiments seem to be dealing with another effect, with hotter molecules in a closed container acting as if they were heavier than cooler molecules when normal convective flow is restricted.
Not as I see it. Nikolov and Zeller show (a) a huge discrepancy between true blackbody temperature and actual Earth surface temperature (b) a link between atmospheric pressure and surface temperature, that can cope with this massive increase of “greenhouse effect” where the CO2 thesis becomes strained to the point of being ridiculous.
Gravity is heavily implicated.
Graeff’s measurements AND calculations (which fit data well) show a thermal gradient due to gravity well in excess of the adiabatic lapse rate.
The implication is that in the free atmosphere, at least, convection nullifies most of the gravitational effect… but not quite all… and what remains is the adiabatic lapse rate.
It was Anthony Watts (and others) who believed that N&Z’s pressure/gravity thesis contradicted the Second Law, or rather its believed consequence (believed by Maxwell etc but never tested) that a column of air in equilibrium would have the same temperature top and bottom. Graeff demonstrates with both experiments and theory that this is not the case – and does not in reality contravene the Second Law – it only puts the record straight on this untested belief of its effect on a column of air.
Trick, re. your thermocouples (6) and (7). I’ve looked and it seems too fiddly to alter.
My guess is that Graeff decided not to include them in his improved diagram, because it’s really impossible to draw them at this scale. However, he does indicate their lengths in the text, and these lengths correspond Ithink to two height measurements on the RHS of the diagram. I cannot say with more certainty. But I am pretty sure he would have measured the thermocouple span rather than the full flask size, or at least used the thermocouple span in his calculation to convert the temperature gradient from a pure temperature figure K to a gradient K/m.
Again, a little point we can hopefully ensure is not left ambiguous, when we do replication.
Q. Daniels 8:11am:
Add beads to: “To minimize convection.”
The glass beads in B74 add confusion so far as I can see. There is no theoretical reason to minimize convection since the closed container theory does not suppress convection in any way in showing a lapse will exist in standard air at LTE w/gravity. That’s why I asked if experiments have been performed w/o beads.
Minimizing radiative heat effects might be a good use of the beads as the theory assumes dry ideal air, adiabatic container control volume. It is possible powder is to dry the air or add more confusion than eliminate.
I’m too busy happily reading Truesdell 1980 et. al. at the moment to dig into Graeff’s writings.
Lucy 12:59pm “…(believed by Maxwell etc but never tested) that a column of air in equilibrium would have the same temperature top and bottom. Graeff demonstrates with both experiments and theory that this is not the case – and does not in reality contravene the Second Law..”
Graeff is testing a different set of closed column constraints than classic (“Maxwellian”) theory which for the atmosphere was applied primarily to get an isothermal mid-air column open to work transfer at both ends (constant enthalpy & mass). Closed container classic theory invoked the 0th law (haphazardly) to derive the isothermal barometric equation by simply (and now shown incorrectly) demanding equilibrium of temperature in the column. Much of the thread(s) on WUWT focused on debating this 0th law demand IIRC.
The incorrect 0th application seems to be verified so far by B74 experiment being non-isothermal if replicated enough independently w/o glass beads. Some apply 0th incorrectly to only one body in control volume of interest being analyzed or tested – the closed air column in B47 – when 0th is actually a three body law.
Some write the 0th is really derived from 2nd law as you write there is no hope of violating.
Trick 3:35pm: I have difficulty understanding you here.
Let me put what I understand in simple language, that I do not think is far-removed from what Maxwell understood. I have avoided using the words isothermal, enthalpy, zeroth law. I trust this does not lessen the sense, but makes it more accessible to people.
Maxwell believed that a column of air would have the same temperature top and bottom, if it was in equilibrium, all other things being equal. This is what I (and I think Maxwell) would regard as classic Maxwellian theory. Now to me, if one could snap a very long tube round a very high column of air, reaching up above the snow line, one would catch the classic Maxwellian setup in practice: and it would not have the same temperature top and bottom, but as Loschmidt said, would be warmer at the bottom, in fact much the same temperatures as outside the tube. The tube in place would stop the gross effects of convection over distance (wind), but would not stop convection completely. Thus the air inside would show something like the classic adiabatic lapse rate. And this would not change even if the tube were in a room with a thermostat so that day and night temperatures were the same.
However, the narrower the tube, the more the convection would be impeded. All Graeff has done with the glass spherules is to make the “tube effect” so narrow that convection is pretty well stopped. And a temperature gradient appears that is about ten times the normal adiabatic lapse rate. No heat, no pressure, no force of any kind is applied except gravity.
The pure gravitational effect is just big enough to measure with the current setup and limits of tolerance – but it still fluctuates a lot owing to air’s comparatively low thermal inertia, and averaging out over a long period is needed. If we were to set up the experiment without convection impeded by the glass powder, I would still expect a negative gradient, but too low to measure with certainty, with current setup. I would in fact expect to rediscover the adiabatic lapse rate.
Lucy 5:09pm: “Maxwell believed that a column of air would have the same temperature top and bottom…”
Ok, I’m with you.
Lucy continues: “…snap a very long tube round a very high column of air, reaching up above the snow line…one would catch the classic Maxwellian setup in practice: and it would not have the same temperature top and bottom.”
I lose you here, please explain further or more clearly. You seem to say Maxwell will have same temperature classically top and bottom then quickly catch classic Maxwell will NOT have same temperature top and bottom.
Lucy continuing: “ If we were to set up the experiment without convection impeded by the glass powder, I would still expect a negative gradient, but too low to measure with certainty, with current setup.”
This is very disappointing. Informed critics then are free to point at the powder preventing convection as the sole reason the column has any negative gradient at all. If the B74 style air experiment cannot find a gradient without the powder they will debate experiment proves there is in fact no gradient and classic Maxwell theory has correct results for a closed insulated container in gravity field and by extension to the real atmosphere.
This would lead to search for a possible issue (yet to be found) with more recent improved integration in non-classical theory.
Lucy; before I read the comments, I suggest you go easy on the “Freedom of Speech” stuff. The 1st Amendment protects critics of the government, and does not mandate or create any right to a hearing in other respects. IOW, no blog is obliged to give a platform to anyone.
Trick: I should have said “…snap a very long tube round a very high column of air, reaching up above the snow line…one would catch the classic Maxwellian setup, put to the test. But in reality, it would not have the same temperature top and bottom…”
As to you being disappointed by the difficulty of setting up a no-glass-impedance experiment;
(a) perhaps we can devise this experiment. But at a guess, it will have to run for months and months to achieve a statistically significant result at the scale of feasibility we are currently dealing with, with shoestring funds, equipment, etc.
(b) I disagree, I think informed critics are not free to blame the powder. The fact of a negative temperature gradient at all is the thing of real significance, of most importance, and in that sense it matters not a jot what the material is. There shouldn’t be a negative gradient at all, whatever the substance. You also have to consider Graeff’s other experiments and take them all together because their results reinforce each other. Graeff did experiments in which the core column was regularly inverted. Always it re-established the negative gradient in about a day. It is really difficult to explain this by anything other than gravity. Can you? (theory next instalment)
Hope this helps. I still puzzle myself: but am applying Graeff to Erl Happ at present 🙂
Brian, thanks for your advice. I will have to look up the First Amendment (not being a US citizen) and certainly will try to go very gently, remembering that for every finger pointing at someone else, three point back towards myself. But that is for next article, not this one. Hope this answers you.
I wonder — do the swings in the ‘middle axis’, 3rd figure, track barometric pressure? Since the measurements are absolute, not relative, this seems like an interesting possibility and possible relevant datum.
Ok, Lucy I understand your 7:44pm update & snipped it in but then quickly you lose me again with…
“…but as Loschmidt said, would be warmer at the bottom, in fact much the same temperatures as outside the tube. The tube in place would stop the gross effects of convection over distance (wind), but would not stop convection completely. Thus the air inside would show something like the classic adiabatic lapse rate.”
The classic iso solution is a 0 lapse rate b/c as you say “Maxwell believed that a column of air would have the same temperature top and bottom..”
Right? So I corrected that myself to keep parsing my way thru… Then I ran into:
“However, the narrower the tube, the more the convection would be impeded.”
I cannot see this unless you are talking very near the column walls where boundary layer physics have to take on an effect. I think these effects are not of interest. Not sure. What do you say knowing Graeff’s writings? Maybe just a reality to live with given the column aspect ratio length/width reduction forced on the shoestring experiments.
“ And a temperature gradient appears that is about ten times the normal adiabatic lapse rate.”
By this I take it you mean the normal lapse rate of the standard atmosphere. Right? Not the lapse rate that is calculated by closed container non-iso ideal theory? (See Verkley 2b for that.)
(a) Yeah months and months, but if that is the finding so be it. Seems like the expense of running the experiment is just a longer shoestring. Still fairly small for data logging electricity unless I miss something. The red does damp much faster than the blue in B74.
(b) Critics not free? Whoa. OTOH I see no restraint offered or accepted. There would be no restraining them concluding evenly wrongly the difference in the blue and red curves from green must be somehow all, ALL, the result of powder holding back their precious convection. LOL.
Trick wrote:
I cannot see this unless you are talking very near the column walls where boundary layer physics have to take on an effect.
That’s what’s being referred to.
By this I take it you mean the normal lapse rate of the standard atmosphere.
The Dry Adiabatic Lapse Rate. The logic refers to the instability of any gas which has a lapse rate greater than the DALR. In this case, macroscopic movements of parcels of gas within the volume are likely to cause the warmer parcels to rise and the cooler parcels to fall, aka convection.
Graeff’s solution is to impede all macroscopic movements, thereby impeding convection.
Q. Daniels 11:32pm –
Oh ok, I see, thx. 10x standard DALR using powder convection impediment in B74. I wonder what the difference is if no convection impediment is employed? More or less than 10x? Or is that known or too small to measure say at 1x?
Too, would be especially interesting to see the lapse rate difference from that expected by no convection impediment ideal theory. Expect higher than 1x. Haven’t followed Graeff exp. history.
Trick wrote:
I wonder what the difference is if no convection impediment is employed? More or less than 10x? Or is that known or too small to measure say at 1x?
I tried to look at this question, and found myself heading for Fluid Dynamics. I stopped before I lost my lunch. It was a close thing.
The best I can offer is a guess of measured/DALR=1 +0.5/-2.
A value of less than 2 is going to be that much harder to measure.
The bottom line of all of this is if the pressure and density differentials exactly track each other with altitude, dp/dρ = constant at all altitudes, you are going to have an isothermal situation. However, if that ratio changes with altitude, you are going to have a lapse rate. If you are ever going to identify the ‘why’ you will have to identify the reasons that they diverge, and I can think of many, that is why nothing is ideal. (Or analytically why they never diverge.) It seems ideal may be isothermal mathematically, however in reality, you are bound to have a lapse rate of some degree. Knowing it makes heads sore trying to gather all of the coupled equations simultaneously, maybe one of those factors at a time would be far easier.
Trick, here’s a restatement. Thanks for making me improve my language, hope it works this time:
Maxwell believed that a column of air would have the same temperature top and bottom, if it was in equilibrium, all other things being equal. This is what I (and I think Maxwell) would regard as classic Maxwellian theory, his theoretical belief, his thought experiment.
Now my thought experiment is, that if one could snap a very long tube round a very high column of air, reaching up above the snow line, one would be performing what Maxwell’s thought experiment performs: but behold! it would NOT have the same temperature top and bottom as Maxwell believed, but as Loschmidt said, would be warmer at the bottom, in fact much the same temperatures as outside the tube. The tube in place would stop the gross effects of convection over distance (wind), but would not stop convection completely. The air inside would show a negative temperature gradient fairly close to the classic adiabatic lapse rate, somewhere between that and Graeff’s measured rate for convection-impeded air. And this would not change even if the tube were in a space with a thermostat so that day and night temperatures were the same.
However, the narrower the tube, the more the convection would be impeded. And this “near-surface” convection impedance effect is crucial. It is precisely why insulators like feathers and expanded polystyrene work.
All Graeff has shown in practice with his many experiments, using glass spherules and other convection-inhibitors, is to make the “tube effect” so narrow that convection is pretty well stopped, and a temperature gradient of ~0.07K/m appears that is about ten times the normal adiabatic lapse rate of ~0.007K/m = 7K/km (I know, that’s a crude approximation to keep figures easy to remember). No heat, no pressure, no exposure to radiation, no force of any kind is applied except gravity.
and yes, Trick, of course critics can say what they like 🙂
Brian H says: June 12, 2012 at 7:51 pm | Reply w/ Link
I wonder — do the swings in the ‘middle axis’, 3rd figure, track barometric pressure? Since the measurements are absolute, not relative, this seems like an interesting possibility and possible relevant datum.
Take care what kind of “absolute” you mean. The figures are the temperature GRADIENTS that were measured in degrees Centrigrade or Kelvin, and each line tracks for a slightly different height measurement. These measurements have not, on that graph, been converted into true gradients ie Kelvin per metre. Excuse: this was an early experiment, perhaps it was impossible to correct the graph later on without loss of detail. However, the next graph showing cumulative averages, does make this correction, and the y-axis is scaled to gradient as K/m.
From talking with Graeff, and other hints in his book, I get the impression we have two factors at work causing the fluctuations. First is the low thermal capacity of the air, compared with the vessels surrounding it. And we are trying to measure temperature gradients that are of the order of one hundredth of the surrounding gradients and fluctuations. Second factor is that, for whatever reasons (one can ponder this) the top of the air core warms (and cools) slightly quicker than the bottom, with respect to external changes. So if the temperature outside rises, the gradient may rise into the positive area; and if it falls, the gradient may become more negative than the true value – hence longterm averaging is so important.
Lucy 10:08am: “..a temperature gradient of ~0.07K/m…about ten times the normal adiabatic lapse rate of … 7K/km”
Yeah closed insulated experiment of 70K/km is about 10x 7K/km actual DALR 6.49K/km standard.
So…experimentally the lapse with edge effects and powder is WAY more than Maxwellian classic 0 w/o edge effects and powder in closed container. Need some discussion and thinking on what Maxwell et. al. classic theory would derive for how the powder and edge effects would modify the lapse if at all.
Then think about the edge effects and powder on recent closed container theory if any.
Hi Lucy
You must be exhausted fielding all these queries, and now I have another:
If Graeff reduced the tube diameter to lessen convection by exploiting the boundary layer, why didn’t he go the whole way and use tubes that were a couple of millimetres diameter or whatever diameter allowed the boundary layers against the glass to meet in the middle? This would almost cut off convection and negate the use of beads.
I think I might guess the answer: was it because the thermocouples are too bulky to measure such a fine column? Or that their tendency to sap heat from the very thing they are measuring would be amplified because the heat energy in the air column would be negligible?
It’s a shame if that’s the case because it would be a neat experiment if one could analyse just an air column, pure and simple.
Scute,
Any effect is thermally short circuited by the in context highly conductive walls. Alternatively there is a thermal gradient in the solid as well.
Packing the space with an in context highly thermally conductive solid has the same effect.
This is a minor point relative to what Graeff has omitted to say.
tchannon says, June 14, 2012 at 1:41 am:
Scute, Any effect is thermally short circuited by the in-context highly conductive walls. Alternatively there is a thermal gradient in the solid as well. Packing the space with an in-context highly thermally conductive solid has the same effect.
Agreed. I can’t see much conceptual distinction between doing the experiment with glass sludge and doing it with solid glass.
This is a minor point relative to what Graeff has omitted to say.
Spot on, Tim!
There are so many omissions of detail in Graeff’s paper that it is very difficult to evaluate its credibility. And, because Graeff is mysteriously absent from this blog trail, Lucy is having to take all the flack, which really isn’t fair on her.
For me, disturbing questions abound. For example, in the B372 water experiment:
(1) There is no explanation of why a variety of different insulating materials have been chosen rather than just one really good one.
(2) There is no explanation of why there are so many nested containers (1st diagram above; or Fig.1 in Graeff’s paper). Why not just bury the two inner tubes inside one nice big insulating jacket inside one sturdy outer aluminium container?
(3) Why are the two tubes (apparently) so close together. It is surely just as important not to have heat leakage between them as it is not to have heat leakage between each of them and the ambient environment.
(4) The thermistors (plots 9 to 14 in the fifth diagram above; or Fig. 2 in Graeff’s paper) are apparently all positioned further in towards the centre than the outermost aluminium housing, i.e. they are all separated from it by one or more layers of insulation. Yet they show larger temperature swings than plot 8 which appears to be the outermost sensor of the lot and which shows comparatively little variation over the whole period of the experiment. One would surely expect it to be the other way round?
(5) It doesn’t help that Lucy’s tentative labelling of the plots 9 to 14 have still not been confirmed by Graeff, making it a rather dispiriting process trying to puzzle things out.
An additional major problem for me in Graeff’s paper is the way he jumps back and forth between quoting the air and water experiment results, rather than laying out the various resulting gradient figures in one place with a suitable accompanying narrative, developing the story consecutively. (At one point he even gets the gradient for the pure water tube wrong, 0.12K/m when he means 0.012K/m. OK, it’s a typo but it really added to my confusion on my first read through.)
I think the distinct water/water+glass/air experiments are not only muddled in presentation (a mistake that Lucy has unfortunately compounded above, as has already been pointed out) but they are also bound to raise the suspicion that: (i) the air experiments were rather iffy; so (ii) he moved on to water experiments but found they were rather iffy too; so (iii) he moved on to water+glass particle experiments.
I don’t have any problem with this last observation as such, because he is an empiricist and this experiment is operating right at the limits of feasible temperature measurement which he would not have been able to predict in advance. What he has done represents a journey of valid experimental investigation carried out over several years. I guess the problem is that the journey doesn’t come over quite that positive way in the paper (nor in Lucy’s rendering) and this is a pity.
But having listed all the above horribly negative things, I must say that I still have a gut feeling that he has probably found something significant and has shown that there is now at least a ‘case for investigation’. As I have said here before, I don’t think for one moment that it violates any of the Laws of Thermodynamics. But what he may well have demonstrated is the first experimental glimpses of what a growing number of scientists and engineers (including me) have believed for some time and with growing certainty: that the average temperature gradient in the atmosphere is wholly accounted for by its weight and not at all by the presence or absence of so-called greenhouse gases.
So the positive message is that we must surely build on this pioneering start. I think it would be worthwhile constructing a much more ambitious (and expensive) experimental apparatus. This will take money and time. In my view there is absolutely no point in just replicating Graeff’s experiment on a shoestring. It won’t convince anybody, least of all us skeptics!
Lucy,
A MAJOR mistake has been made with the glass experiment!
This experiment ASSUMES that the weight of water on the surface of the cylinder is the same as at the bottom of the cylinder.
Now take an ordinarily spoon and stir in a rotation and this will create a funnel in the center.
WHY?
Because the levels of mass are slightly different and heavier.
If all parts being equal, there would be NO funneling of water mass.
The shape of our planet being an orb has a significant reason, but our experiments do NOT allow for motion forces that are unseen.
Trick was saying we need more thought on way glass beads could somehow effect the gradient. I was mulling over this aspect. Most the talk has been on limited convection and edge effects. But something just struck me and I have no idea as yet if this could have any real affect at all.
When you fill a column with glass beads, being solid, they support themselves and the beads higher in the column by the stress, and I’m not going the address that. But when you pour a liquid in to fill all of the tiny gaps between these beads, each tiny parcel of that liquid no longer has to support the liquid vertically above, or does it? Well, it does have to some greatly reduced amount and each parcel mostly bears it’s weight downward on the beads, not the liquid below. Could this somehow affect the density gradient within the liquid vertically? And if so, could that altered density gradient then affect the temperature?
In some respects each parcel of liquid (or gas) within this matrix of solid is basically ‘at the bottom’ to some degree, for most of the support is supplied by the solid bead just below it.
Haven’t taken the time yet to get too deep on that thought. First, heading to bed myself but maybe someone might give that a thought or let me know if that is just a truly crazy idea, physics has good way to toss new thoughts curves, or worse, spit balls. 😉
Trick says: June 13, 2012 at 1:15 pm
Yes. I set to thinking about edge effects and imagining being a molecule. What I notice about outside is that edge effects work to a considerable distance, in real life. Shelter from wind; wind far lower near the ground; jerseys and feather duvets and all insulators that utilize “trapped” air. Against which, tornadoes and hurricanes start in the air.
I don’t think there is anything especially magical with air: with water edge effects I don’t know.
Still, nothing detracts from (a) observed negative temperature gradient (which “shouldn’t exits”) while surrounded by positive one (b) observed results seem to match theoretical results closely (next article).
Scute says: June 14, 2012 at 12:41 am
You’ve answered your own question I think.
Thanks for sympathetic thoughts. It’s ok.
David Socrates says: June 14, 2012 at 11:00 am
I’ll take your questions one by one. It was difficult to know what to include or omit, for the sake of not making the piece too long or too short, and the only solution is to allow questions. I have either direct answers or educated guesses, all arising from actually having read Graeff’s book (yes, another plug!) and having met him and examined the experiments myself. For various reasons, the seminar this year was not as concentrated on examining and replicating experiments as it has been sometimes I think, so I am hoping to return presently with a few others, to pick up further details.
(1) There is no explanation of why a variety of different insulating materials have been chosen rather than just one really good one.
I think there are likely various reasons. Cost and availability from scrap merchants. He made extensive use of scrap merchants. What would one do in his shoes? Shape and ease of fitting at that scale. Degree of “total insulation” needed.
(2) There is no explanation of why there are so many nested containers (1st diagram above; or Fig.1 in Graeff’s paper). Why not just bury the two inner tubes inside one nice big insulating jacket inside one sturdy outer aluminium container?
Availability? Rigidity? Heightened effect? Possibly this, since Graeff was experimenting with making-up a coil of alternating insulator and metal-equalizer. He says he found by trial and error what seemed to work best. And like a good engineer he has simply described the materials he used, so that his work can be replicated.
(3) Why are the two tubes (apparently) so close together. It is surely just as important not to have heat leakage between them as it is not to have heat leakage between each of them and the ambient environment.
I agree. And I wonder if the small negative gradient in the “free” water may be the combined effect of “heat leakage” from the convection-impeded water AND the air trapped by the insulation – AND the glass – AND the pvc.
Perhaps it was “needs must suffice” – a limit on supplies sizes, particularly the inner aluminium tubes that were maybe more important in temperature equalization, than allowing separation.
Still, we have the most important thing – a negative gradient that shouldn’t be there.
That’s long enough for one post…
David Socrates: (4) The thermistors (plots 9 to 14 in the fifth diagram above; or Fig. 2 in Graeff’s paper) are apparently all positioned further in towards the centre than the outermost aluminium housing, i.e. they are all separated from it by one or more layers of insulation. Yet they show larger temperature swings than plot 8 which appears to be the outermost sensor of the lot and which shows comparatively little variation over the whole period of the experiment. One would surely expect it to be the other way round?
No, you misread. The thermistors are measuring actual temperatures (and yes, with these swings) scaled on the RHS, but plot 8 is measuring GRADIENT (scale to LHS). I know it’s a lot to take in. But I can see Graeff’s logic for putting all these together. The subtle way in which the blips follow the changes in temperature direction are very telling. Also very telling is the fact that the gradient is maintained at a steady level, (it’s a much finer scale) despite “riding on” the “carrier wave” of temperature fluctuations operating at a much bigger scale.
In this context, the jaggedness of 8 is natural (at the fine scale of the LHS), as well as its strong but reasonably steady positive gradient. Both factors are because 8 is close to external conditions where there is a positive temperature gradient in the room, fluctuating within overall temperature fluctuations.
I went through your doubts and misunderstandings too, initially.
David Socrates: (5) It doesn’t help that Lucy’s tentative labelling of the plots 9 to 14 have still not been confirmed by Graeff, making it a rather dispiriting process trying to puzzle things out.
Graeff emailed me to say it really doesn’t matter which number belongs to which line, because the thermistor readings’ scaling is not that trustworthy. What is important is to see them all move together, parallel, which gives confidence that they are measuring temperature together, even if it is uncertain as to exactly what the temperature is.
This may feel irritating, but then, what can one do? I now agree with Graeff, and think it’s important to relax – this one really does not matter too much, compared with the existence of ANY negative gradient. And the measurements from thermocouples we can trust. Graeff said something that was important for me to hear, to help me understand. He said, in effect, “eventually, after you have done lots of experiments with different variations, you just get a feeling for what is working and what is essential”
David Socrates: An additional major problem for me in Graeff’s paper is the way he jumps back and forth between quoting the air and water experiment results, rather than laying out the various resulting gradient figures in one place with a suitable accompanying narrative, developing the story consecutively. (At one point he even gets the gradient for the pure water tube wrong, 0.12K/m when he means 0.012K/m. OK, it’s a typo but it really added to my confusion on my first read through.)
I think the distinct water/water+glass/air experiments are not only muddled in presentation (a mistake that Lucy has unfortunately compounded above, as has already been pointed out) but they are also bound to raise the suspicion that: (i) the air experiments were rather iffy; so (ii) he moved on to water experiments but found they were rather iffy too; so (iii) he moved on to water+glass particle experiments.
I don’t have any problem with this last observation as such, because he is an empiricist and this experiment is operating right at the limits of feasible temperature measurement which he would not have been able to predict in advance. What he has done represents a journey of valid experimental investigation carried out over several years. I guess the problem is that the journey doesn’t come over quite that positive way in the paper (nor in Lucy’s rendering) and this is a pity.
David, I’m confused now. Here is Graeff’s air experiment B74 written on his website with his original sketch which I replaced with the 2011 paper’s drawing, coloured by yours truly. Here is his later water experiment B372 written-up as a paper. Here is his paper presented to Sheehan’s 2011 conference, which refers to the air experiment, the water experiment, the turning experiment, and other experiments, but all with rather brief mentions.
I found Graeff’s style very confusing at first. His editor Marianna knows it could do with vast improvement. I guess I made a wrong choice by putting the water apparatus diagram above the whole air experiment. I thought I needed to put it in there because people here have probably already seen it so they would immediately say “ah, here’s Graeff’s experiments” and I would work from the familiar to the unfamiliar. Bad judgement of mine.
But that’s life. Life comes confused, and gradually we sift out what matters, and next thing, those confusing sounds are words that make sense and we say, why, it’s so simple and so obvious really! The more I re-read Graeff’s book, the more logical his meanderings and repetitions and heartrending stories all seem. They didn’t at first. But I persevered because I thought, this work has the potential to put the whole of Climate Science on a better footing, together with Ned Nikolov and Karl Zeller – and others. And more. It’s important to be free to shake up conventional perspectives – with good evidence.
Yes, occasionally a decimal point has strayed.
Yes, Graeff would I am sure agree that all the experiments are iffy – none of them should be producing negative temperature gradients surrounded by a positive one. David, please please do read his book. I think you would appreciate it. He describes beautifully how one “iffy” attempt led to another slightly less “iffy” one and to another… and another.. and how over time he learned and improved his techniques, even while not lavishly funded… how does one decide how best to use one’s time and resources when one is 84?
So the positive message is that we must surely build on this pioneering start. I think it would be worthwhile constructing a much more ambitious (and expensive) experimental apparatus. This will take money and time. In my view there is absolutely no point in just replicating Graeff’s experiment on a shoestring. It won’t convince anybody, least of all us skeptics!
David, be very careful of underestimating Graeff’s engineering ability. He is a genius IMO. You are unlikely to succeed without fully appreciating that even his apparent failures and limitations may be revealing important details. Graeff says that one Chinese professor has been trying to replicate, using a centrifuge… but no description of insulating the device…
As I said, I’m hoping to visit him again. I think you in particular would benefit from a visit, and enjoy the meeting. It would also help us to work together as a team. If you have money for improved replication, fantastic, but you have to ensure you aren’t missing simple tricks. Nothing will replace a keen eye and precise imagination.
I will email him and invite him again to contribute here, directly.
I apologise for not being around much. I’m firefighting.
wayne says: June 14, 2012 at 1:14 pm
Wayne, neither density nor pressure come into Graeff’s experiments. The factors are gravity, height, and specific heat and degrees of freedom of the substance in question.
Nikolov and Zeller work with pressure. But this too is an effect of gravity. Now please correct me if I’m mistaken. I seem to remember the adiabatic lapse rate is linear with height up to the tropopause. This would then seem to mirror Graeff’s linear rate, not the pressure decrease rate which is logarithmic if I’m not mistaken. Over a substantial height, it might be important to distinguish between the two specific heats (at constant pressure and constant volume), but I don’t think it matters here, certainly not for the basic evidence of negative temperature gradient that “should not be there”.
Lucy:
“Glass beads used in water convection impedance… were these also hollow? … Theoretically, air has a gradient of 0.07K/m while water’s gradient is 0.04K/m yet the measured “water” gradient is 0.05 K/m.”
nice observation! The air in the glass beads is something I had overlooked when thinking about these experiments.
“Graeff says that one Chinese professor has been trying to replicate, using a centrifuge… but no description of insulating the device… ”
indeed. While the Chinese guy’s measured gradients matched his formula, when I did a centrifuge experiment all I got was wind-chill effects – the whole temperature of the centrifuge dropped considerably making any gradient measurement dubious. If he was working in a warmer climate, maybe he got wind-warming effects http://en.wikipedia.org/wiki/Humidex (not sure how to interpret humidex for a thermometer, but might be relevant)? Definitely a case for working under vacuum, which complicates things.
Have you been getting a parts list together? Even if you wish to wait until the second visit before buying anything, it would be good to have some kit in mind to discuss with Roderich when you meet him again.
In a container with a pressure reduction from bottom to top so that there can be expansion with height:
with circulation – lapse rate.
without circulation – isothermal.
because with no circulation the energy will travel through the material only by conduction which will equalise over time.
Graeff specifies no convection (at equilibrium) which means no circulation which should mean isothermal but his results show otherwise.
How does he ensure that there really is zero circulation ?
Is zero circulation possible in a container on a planet spinning through space ?
Gravity could be causing the non isothermal result not via its vertical pull on the materials in the container but by applying a centrifugal force inducing a circulation.
How could one screen that out from a surface bound experiment ?
To clarify, the temperature should become isothermal but because of the continuing pressure differential the molecules at the lower pressure would then be carrying more potential energy than those at the higher pressure.
Now, that should be the position with no circulation as proposed by Graeff UNLESS gravity intervenes in some way. But one doesn’t need to invoke any gravitational effect, merely a circulation which Graeff may not have been able to suppress.
If one introduces a circulation the molecules at lower pressure move to higher pressure so some of the potential energy converts to heat and the temperature rises as a result of compression.
Meanwhile the molecules at higher pressure move to lower pressure so some of their heat converts to potential energy and the temperature falls due to decompression.
And then you have the lapse rate with denser molecules warmer than the less dense molecules.
The secret is that the changes in pressure swap potential energy for heat with the sign of the effect being opposite at each end of the pressure gradient so as to produce the lapse rate.
A simple redistribution of the available energy so no perpetuum mobile and no breach of the Laws of Thermodynamics.
Note that the whole process implies that with no circulation the equilibrium state must be or must be capable of becoming isothermal hence my suggestion that Greaff’s results may be a consequence of a circulation of some sort remaining in his container despite his best efforts to exclude external influences.
Lucy – if you haven’t already found it, check out http://paias.org/Science/Entropy/entropy1.htm where the ideas behind 2LoT are dissected. The total block on questioning this Law has stopped a lot of questioning of it – the real basis for it is that so far we haven’t found anything that breaks it, not that it is by definition unbreakable. If you get down to single molecules, Newton’s laws of motion (or the relativistic equivalent) take precedence since 2LoT only really applies to cyclic things and large numbers. With nanoengineering becoming more used, you can expect some devices that break the rules.
Thanks Lucy for a very interesting post.
For validation, it would help to access calibration lab quality equipment to eliminate most measurement uncertainty.
See: Guidelines for Realizing the International Temperature Scale of 1990 (ITS-90)
e.g., A water triple point cell defining 0.016C
Gallium “point 29.7646 C (requires also the triple point of water”)
(“Confidence in and reproducibility of the gallium melt point is 0.00015 C.”)
NIST REALIZATION OF THE GALLIUM TRIPLE POINT
NIST Temperature & Humidity Group
Then you probably want NIST calibrated platinum resistance thermometers. See:
Standard Platinum Resistance Thermometer Calibrations from the Ar TP to the Ag FP December 19, 2007
Primary calibration lab quality thermometers. e.g.,
Fluke 1594A/1595A Super-Thermometers “Accuracy as good as 0.06 ppm (0.000015 °C)”
Graeff’s method has the potential for an independent method to establish a temperature gradient. Thus it may be worth a grant to test the method at a primary lab like PTB, NPL or NIST etc.
Re: “neither density nor pressure come into Graeff’s experiments. The factors are gravity, height, and specific heat and degrees of freedom of the substance in question.”
Pressure varies with elevation. For a quantitative thermodynamic model of the lapse rate see:
Robert H. Essenhigh. “Prediction from an Analytical Model of: The Standard Atmosphere Profiles of Temperature, Pressure, and Density with Height for the Lower Atmosphere; and Potential for Profiles-Perturbation by Combustion Emissions”. Paper No.03F-44: Western States Section Combustion Institute Meeting: Fall (October) 2003.
^ Robert H. Essenhigh (2006). “Prediction of the Standard Atmosphere Profiles of Temperature, Pressure, and Density with Height for the Lower Atmosphere by Solution of the (S-S) Integral Equations of Transfer and Evaluation of the Potential for Profile Perturbation by Combustion Emissions”. Energy & Fuels 20: 1057-1067. DOI: 10.1021/ef050276y.
This could be refined to account for the variation in gravity with elevation, and using a Line By Line radiation model for the radiation properties.
Use pure gases, not air. e.g. argon, nitrogen, CO2, water vapor.
Lucy
You also will want to measure absolute pressure at one end and the differential pressure top to bottom.
eg. see Paroscientific Digiquartz
2000 absolute pressure
5300 for differential pressure or
Model 202BG Pressure range of ±2 psig “(±15kPa) Resolution better than 0.000001 psig (0.007 Pa); Total accuracy of 0.0004 psig (3 Pa)”
[…] Lucy Skywalker: Graeffs experiments and the second law of thermodynamics […]
Sorry about leaving remarks unanswered so long.
br1 says: June 18, 2012 at 10:57 am
Have you been getting a parts list together?
Effectively, the answer is in the fourth instalment.
Stephen Wilde says: June 18, 2012 at 6:18 pm
Graeff specifies no convection (at equilibrium) which means no circulation which should mean isothermal but his results show otherwise.
How does he ensure that there really is zero circulation ?
All insulators depend on effectively reducing convection to near-zero, by trapping air bubbles: feathers, expanded polystyrene, glass fibre, wool… Then all that remains is conduction, which for air and all the above, is reasonably low, certainly low enough to give time for the negative gradient to reveal itself.
The real point is, that if there were convection, the negative temperature gradient (at the centre of a positive temperature gradient) would not be able to exist at all.
Simon Derricutt says: June 21, 2012 at 11:38 pm
Simon, thanks for that reference. Have a look at my latest piece on Graeff’s theoretical underpinning which shows that we don’t need to worry about the “gambling” improbabilities your ref. suggests, we simply look a bit more closely and carefully so as to explain the experimental anomaly.
However, if you are interested in nano-applications, you might like to investigate Sheehan further since most of the material he’s collected is challenges to 2LoT at this level. But they are theoretical in general whereas Graeff has done the experiments too, and this difference is to me absolutely crucial.
David L. Hagen says:
June 24, 2012 at 3:23 am; 3:30 am; 3:53 am
Thank you very much David for such detailed suggestions. I will keep them bookmarked. These are my thoughts:
(1) I am a know-nothing about all this!
(2) I have discussed some of this with Graeff;
(3) my part 4 article will open up these issues a bit further.
Roderich uses instruments at the limits of their capacity. He showed me how to make a thermocouple using Constantan and I forget the other alloy. He’s aware of the German “standards institute” and he explained how he could use instruments to ten times the “stated” accuracy when measuring gradients rather than absolute temperatures. I can ask him about the platinum resistance thermometers etc. I should think it’s likely Graeff has been in touch with PTB but I’ll ask. Meanwhile there have been other developments I’ll report later.
Pressure: yes of course pressure varies with height – and weather. But in Graeff’s experiment, it is not a significant factor. His equations (that I was referring to) don’t involve pressure directly. Pressure affects air’s specific heat, but only a little. However, your question has unearthed a problem for me and I need to get back to Graeff first but he’s in the States…
Graeff has a pressure-flask of Argon, he’d like to test it. But think about the practicalities of testing it on a shoestring budget. He’s still figuring out that one.
[…] Lucy Skywalker: Graeffs experiments and the second law of thermodynamics […]
Lucy
PS Accounting for self heating and conduction will be a major issue with the temperature sensors.
For gravity to have this temperature effect on a gas in an enclosed column, gas must be allowed to circulate!
How else would the temperature gradient develop if the gas molecules were constrained.
Otherwise some appear to suggest that if the impeding material was hollow gas filled spheres, that the gas within spheres of differing height would maintain different temperatures. In my mind this is not sensible.
Has anyone news of an air experiment without circulation impeding material?
I hope to be able to construct some apparatus to duplicate the air experiment but without impeding material.
Self heating and conduction can be minimised. Using PT100s (platinum 100 ohms at 0 degrees C) are the most popular and most accurate way of measuring temperatures that humans tolerate.
It would be easy to arrange for the current through the PT100s to be off unless a measurement were to be taken. So the PT100 would only be heating the column for say 10 seconds per 6 minutes. The power/heat input from a PT100 would typically be 100uA^2 * 105 ohms approximately 1 microwatt, and this would be injected into the top and bottom of the column equally. The on ratio 10/360 = 0.0277 so the power input into the column is approximately 0.0277 * 1uW * 2 = 55nW.
Not much compared to the room environment?