'Twas an inspired idea of Dung's to revive this thread, and some interesting stuff followed. Unfortunately there was an unwelcome intervention from someone (yes, him again) all too forcefully asserting, in effect, that if the 'right' people don't say it, it can be dismissed out of hand. Ned Nikolov (a Bulgarian emigre to the USA I believe and thus naturally resistant to effete Western BS), whether or not his and Karl Zeller's theory is proven correct in part or whole, is a superlative communicator of science and for that reason alone is well worth reading.

Mike Jackson is right to be annoyed. His posts always make absolute sense and are eminently readable - no obfuscatory and convoluted (ab)use of the English language for him. Far too much time and blog space is indeed wasted in repetitious and dreary displays of gobbledegook, even if some of those spouting it don't have the insight to recognize it in themselves.

Ned Nikolov[...] whether or not his and Karl Zeller's theory is proven correct in part or whole, is a superlative communicator of science and for that reason alone is well worth reading.

Having just attempted to read it last night, I have to take issue with this - it's impenetrable, and full of polemical statements. I hope they have stumbled on a chink the GHE armour, but to say they are great communicators is egging a rather stodgy pudding IMO.

I challenge anyone here to explain the convection problem presented in that paper to me in noramal undergraduate mathematics way. What I suspect is that it's just been swallowed entire by a group of people desperate for anything.

Fair enough TBYJ, and I respect your opinion on that. My recollection of Ned's communication skills is based on the early threads on the subject on Tallbloke's Talkshop, in which Ned directly answered questions on the threads. I was impressed, and some of the more numerately scientific people seemed to be as well.

I'd like to read them, it might help me understand the maths, do you have a link?

Here's one of them TBYJ. Three of the 'Most Commented Posts' on the Talkshop's main page are N&Z threads.

http://tallbloke.wordpress.com/2012/01/17/nikolov-and-zeller-reply-to-comments-on-the-utc-part-1/

Over the past year, at different blogs, there has been discussion of different aspects of the Nikolov and Zeller theory. This has spilled over into debate about the adiabatic lapse rate, the importance of radiatively active gases, the role of convection etc. I've just glanced at the N&Z summary and read the following statement:

"..pressure directly controls the kinetic energy and temperature of the atmosphere".

This statement alone should be enough to assign the N&Z theory to the garbage can of discarded ideas. It is central to the kinetic theory of gases that the average kinetic energy of the molecules depends only on the temperature of the system.

On January 1st Roy Spencer at his blog restated the basic principles of the GHE and Lubos Motl re-iterated these. I suggest readers visit both these postings and consider them carefully. I am in complete agreement with both these scientists on the basic principles of the GHE. Without any radiatively active gases the atmosphere would be isothermal and hydrodynamically stable. There would be no lapse rate and no 'pressure heating' as suggested by N&Z. The atmosphere, through thermal conduction, would assume the surface temperature of a grey body Earth.

The crux of the problem seems to be a misunderstanding of the adiabatic behaviour of an isothermal gas column in a gravitational field. There is an apparent ambiguity in our perception of what should be happening. On the one hand we might assert that the temperature is equal at every height in the column since it is isothermal. On the other we then have the problem of the loss of kinetic energy of molecules as they move to higher elevations. Since temperature is a measure of the mean kinetic energy of molecules then surely the gas temperature should decrease as one rises up the column.

This ambiguity in our perception was elegantly considered in 1985 by Coombes and Laue who pointed out that it is the mean kinetic energy of the local assemblage of molecules that defines the temperature. As one moves to higher elevations in the field the total number of molecules decreases, as does the total energy whilst the mean energy (and thus temperature) remains constant. They show that the Maxwell distribution is invariant as one changes altitude in the column.

The take home message is that the lapse rate comes about through the adiabatic expansion and compression of the atmosphere as it convects and is not a function of a hydrodynamically stable atmosphere in a gravitiational field which is isothermal. Convection would not occur in an IR transparent atmosphere since it becomes isothermal at the planetary grey body temperature.

References:

Coombes, C and Laue, H, 1985, A paradox concerning the temperature distribution of a gas in a gravitational field., Am. J. Phys, V53, 272-273

rhoda

Now, does it mean that any energy used to heat the N2/O2 bit of the air (ie, nearly all of it) is taken out of the radiative equation

Not entirely, after being heated, O2 and N2 molecules may then collide with a CO2 of H2O molecule, and excite it, and those molecules ARE able to emit photons, so it goes the other way too. The heat energy can be turned back into IR by this mechanism.

This is why claims that greenhouse gases being at 'trace levels' and thus cannot contribute to warming or cooling are off the way off the mark - the heated air, containing the usual atmospheric mix of gases can ONLY emit IR ito space through greenhouse gases! O2 and N2 can't emit!

(Of course, the air wouldn't be hot in the first place if it wasn't for GH gases, so it cuts both ways :)

Paul Dennis,

I have no doubt at all that you know much more about this than I do. As a scientifically literate non-scientist (I got about 90% correct in a science quiz WUWT once linked to) I try to keep an open mind about the scientific arguments, knowing that historically many long-cherished theories have had to be discarded in the face of new evidence.

Ironically Roy Spencer and Lubos Motl are two of the scientists in the climate blogosphere I respect the most, and I visit their websites regularly. On the other hand Willis Eschenbach, an autodidact with no formal relevant training, is a divisive figure who pilloried N&Z via a defective attempt at ridiculing their mathematical skills, even though they are both physics PhDs and soon put him in his place. This incident made me more inclined to look favorably on what they are trying to say with their theory. I still don't know if the theory has much if any merit, but surely alternative viewpoints are part of what science is all about.

Chris M,

From reading what I've done so far, I can buy the spherical SB problems with the IPCC estimate for the temperature difference attributable to having an atmopshere, unfortunately this just makes the GHE (or ATE) larger than we thought - now at 93K-177K instead of the usually assumed 33K. While finding such a mistake is a real coup, it appears to make matters worse for those arguing against the GHE.

In the paper they then use the existence of this erroneous estimate by the IPCC to say that radiative GHE CANNOT explain such a large number, and claim Thermodynamics cannot account for such a large temperature benefit. That was the point I began to have my doubts, because this was a polemical assertion, not a scientific proof. Why can't the GHE be providing this temperature differential?

The second half of the paper uses the doubts fostered by discovering that mistake to ram yet another 'temperature by pressure' theory which is no different from the ones which came before down the hole. The two halves don't seem to be related, except that the first part is the knock-down, which allows you to let the second part in by the back door.

ChrisM, I remember very well Eschenbach's discussion of the N&Z theory and was not too impressed by the tenor of the discussion. I contributed several times myself, mostly to do with the lapse rate and role of convection and was given short shrift then ignored. At that point I decided that it wasn't worth my while to engage further in discussion over at WUWT. I now rarely contribute there.

Personally I think N&Z are wrong when they discuss Atmospheric Thermal Enhnacement in terms of the ideal gas laws. They are definitely wrong when they state that pressure controls molecular kinetic energy. This misunderstanding is so profound I wonder where it came from.

However, not with standing this criticism their analysis of grey body temperature, the possible role of convection and the empirical observation of increasing planetary surface temperature with increasing atmospheric pressure is interesting and worthy of consideration and critique. Analysis of alternative viewpoints, even when possibly in error, always deepens our understanding of processes.

I hope TBYJ has the time to follow up on your links.

Yes, the air near the surface would be heated by a purely kinetic (convection) mechanism, and you would get a rather thin and unstable temperature gradient, but absolutely not enough to account for the actual measured gradient. Remember, the ground is quite happy to emit photons and would lose most of its energy through IR emission directly to space - there wouldn't be much left for kinetic heating to provide the temperature gradient we know and love.

Simply put, the ground wouldn't warm an O2/N2 atmosphere very much, because it would lose most of its energy by direct IR emission. The only reason O2/N2 warms in the real atmopshere and causes convection, lapse-rates etc. is because of the existence of GHGs absorbing surface IR and heating up all air molecules around it.

Rhoda,

your question concerning the ideal gas column is a really interesting one. I've thought about this myself and haven't come up with an adequate answer. Every sunrise the surface would warm, some of the heat would be transferred to the lower layers of the gas column and destabilise it setting up a convection cell and introducing a lapse rate. I only introduced the Coombes and Laue analysis as a starting point. If you like the most simplest, basic model against which it might be possible to identify the key processes.

Richard,

you and Rhoda have already introduced several new factors which are interesting to explore. As Rhoda pointed out heating and cooling associated with a planet's rotation around it's axis will surely lead to thermal instability. I don't know enough, or indeed anything, about how an atmosphere will respond to the axial rotation, but presumably this will establish pressure gradients with an equatorial bulge of the atmosphere. These will lead to winds. How important these are in an atmosphere without any GHE I don't know.

As I said to Rhoda the model is a starting point to explore how important some processes might, or might not be.

TBYJ,

exactly.

MartinA,

As I pointed out to Rhoda and Richard I agree with what you state above. My comment was in relation to an imaginary planetary body without a GHE as a very simple starting point. I was drawn to it because of the reference others had made to the N&Z atmospheric thermal enhancement effect.

Any theory that relies on an unchanging 'pressure' to provide work to heat an atmosphere against normal thermodynamic equilibrium is little more than a perpetual motion machine, imo.

rhoda,

Absolutely, the higher up the GHG is the easier it can emit IR to space, so the more effective a coolant it is. (Remember that by rising it will have lost temperature, though, through expansion - and for every parcel of air that goes up, one must come down) I read somewhere that without convection the GHE would be about twice as strong.

I think the main cooling mechanism of convection, though is not CO2, but H2O (in the same way as it dominated absorption) - as part of the water cycle, water convected up to altitude, cooling via emission of IR, and then falling back down is the major player in the 'cooling' effect of convection, but of course CO2 has its place here too.

Which is why I think the water cycle plays and will play the major role as a negative feedback mechanism when the temperature goes up - more moist air gets pushed up higher and faster and cools the atmosphere both by emitting photons to space but also by condensing as clouds at altitude and reducing insolation. I think this will be enough to offset the increased warming from all GHG combined. That's contentious though, and I can't prove it. Hopefully someone will soon, though.