Guest Post by Willis Eschenbach
A couple of apparently related theories have been making the rounds lately. One is by Nikolov and Zeller (N&Z), expounded here and replied to here on WUWT. The other is by Hans Jelbring, discussed at Tallblokes Talkshop. As I understand their theories, they say that the combination of gravity plus an atmosphere without greenhouse gases (GHGs) is capable of doing what the greenhouse effect does—raise the earth at least 30°C above what we might call the “theoretical Stefan-Boltzmann (S-B) temperature.”
So what is the S-B temperature, theoretical or otherwise?
A curious fact is that almost everything around us is continually radiating energy in the infrared frequencies. You, me, the trees, the ocean, clouds, ice, all the common stuff gives off infrared radiation. That’s how night-vision goggles work, they let you see in the infrared. Here’s another oddity. Ice, despite being brilliant white because it reflects slmost all visible light, absorbs infrared very well (absorptivity > 0.90). It turns out that most things absorb (and thus emit) infrared quite well, including the ocean, and plants (see Note 3 below). Because of this, the planet is often treated as a “blackbody” for IR, a perfect absorber and a perfect emitter of infrared radiation. The error introduced in that way is small for first-cut calculations.
The Stefan-Boltzmann equation specifies how much radiation is emitted at a given temperature. It states that the radiation increases much faster than the temperature. It turns out that radiation is proportional to absolute temperature to the fourth power. The equation, for those math inclined, is
Radiation = Emissivity times SBconstant times Temperature^4
where the Stefan-Boltzmann constant is a tiny number, 0.0000000567 (5.67E-8). For a blackbody, emissivity = 1.
This “fourth-power” dependence means that if you double the absolute temperature (measured in kelvins), you get sixteen (2^4) times the radiation (measured in watts per square metre, “W/m2”). We can also look at it the other way, that temperature varies as the fourth root of radiation. That means if we double the radiation, the temperature only goes up by about 20% (2^0.25)
Let me call the “theoretical S-B temperature” the temperature that an evenly heated stationary blackbody planet in outer space would have for a given level of incoming radiation in W/m2. It is “theoretical”, because a real, revolving airless planet getting heated by a sun with the same average radiation will be cooler than that theoretical S-B temperature. We might imagine that there are thousands of mini-suns in a sphere around the planet, so the surface heating is perfectly even.
Figure 1. Planet lit by multiple suns. Image Source.
On average day and night over the planetary surface, the Earth receives about 240 W/m2 of energy from the sun. The theoretical S-B temperature for this amount of radiation (if it were evenly distributed) is about -18°C, well below freezing. But instead of being frozen, the planet is at about +14°C or so. That’s about thirty degrees above the theoretical S-B temperature. So why isn’t the planet a block of ice?
Let me take a short detour on the way to answering that question in order to introduce the concept of the “elevator speech” to those unfamiliar with the idea.
The “elevator speech” is simply a distillation of an idea down to its very basics. It is how I would explain my idea to you if I only had the length of an elevator ride to explain it. As such it has two extremely important functions:
1. It forces me to clarify my own ideas on whatever I’m discussing. I can’t get into handwaving and hyperbole, I can’t be unclear about what I’m claiming, if I only have a few sentences to work with.
2. It allows me to clearly communicate those ideas to others.
In recent discussions on the subject, I have been asking for that kind of “elevator speech” distillation of Jelbring’s or Nikolov’s ideas, so that a) I can see if whoever is explaining the theory really understands what they are saying and, if so, then b) so that I can gain an understanding of the ideas of Jelbring or Nikolov to see if I am missing something important.
Let me give you an example to show what I mean. Here’s an elevator speech about the greenhouse effect:
The poorly-named “greenhouse effect” works as follows:
• The surface of the earth emits energy in the form of thermal longwave radiation.
• Some of that energy is absorbed by greenhouse gases (GHGs) in the atmosphere.
• In turn, some of that absorbed energy is radiated by the atmosphere back to the surface.
• As a result of absorbing that energy from the atmosphere, the surface is warmer than it would be in the absence of the GHGs.
OK, that’s my elevator speech about why the Earth is not a block of ice. Note that it is not just saying what is happening. It is saying how it is happening as well.
I have asked, over and over, on various threads, for people who understand either the N&Z theory or the Jelbring theory, to give me the equivalent elevator speech regarding either or both of those theories. I have gotten nothing scientific so far. Oh, there’s the usual handwaving, vague claims of things like ‘the extra heat at the surface, is just borrowed by the work due to gravity, from the higher up regions of the atmosphere‘ with no mechanism for the “borrowing”, that kind of empty statement. But nothing with any meat, nothing with any substance, nothing with any explanatory value or scientific content.
So to begin with, let me renew my call for the elevator speech on either theory. Both of them make my head hurt, I can’t really follow their vague descriptions. So … is anyone who understands either theory willing to step forward and explain it in four or five sentences?
But that’s not really why I’m writing this. I’m writing this because of the claims of the promoters of the two theories. They say that somehow a combination of gravity and a transparent, GHG-free atmosphere can conspire to push the temperature of a planet well above the theoretical S-B temperature, to a condition similar to that of the Earth.
I hold that with a transparent GHG-free atmosphere, neither the hypothetical “N&Z effect” nor the “Jelbring effect” can possibly raise the planetary temperature above the theoretical S-B temperature. But I also make a much more general claim. I hold it can be proven that there is no possible mechanism involving gravity and the atmosphere that can raise the temperature of a planet with a transparent GHG-free atmosphere above the theoretical S-B temperature.
The proof is by contradiction. This is a proof where you assume that the theorem is right, and then show that if it is right it leads to an impossible situation, so it cannot possibly be right.
So let us assume that we have the airless perfectly evenly heated blackbody planet that I spoke of above, evenly surrounded by a sphere of mini-suns. The temperature of this theoretical planet is, of course, the theoretical S-B temperature.
Now suppose we add an atmosphere to the planet, a transparent GHG-free atmosphere. If the theories of N&K and Jelbring are correct, the temperature of the planet will rise.
But when the temperature of a perfect blackbody planet rises … the surface radiation of that planet must rise as well.
And because the atmosphere is transparent, this means that the planet is radiating to space more energy than it receives. This is an obvious violation of conservation of energy, so any theories proposing such a warming must be incorrect.
Q.E.D.
Now, I’m happy for folks to comment on this proof, or to give us their elevator speech about the Jelbring or the N&Z hypothesis. I’m not happy to be abused for my supposed stupidity, nor attacked for my views, nor pilloried for claimed errors of commission and omission. People are already way too passionate about this stuff. Roger Tattersall, the author of the blog “Tallbloke’s Talkshop”, has banned Joel Shore for saying that the N&Z hypothesis violates conservation of energy. Roger’s exact words to Joel were:
… you’re not posting here unless and until you apologise to Nikolov and Zeller for spreading misinformation about conservation of energy in their theory all over the blogosphere and failing to correct it.
Now, I have done the very same thing that Joel did. I’ve said around the web that the N&Z theory violates conservation of energy. So I went to the Talkshop and asked, even implored, Roger not to do such a foolish and anti-scientific thing as banning someone for their scientific views. Since I hold the same views and I committed the same thought-crimes, it was more than theoretical to me. Roger has remained obdurate, however, so I am no longer able to post there in good conscience. Roger Tallbloke has been a gentleman throughout, as is his style, and I hated to leave. But I did what Joel did, I too said N&Z violated conservation of energy, so in solidarity and fairness I’m not posting at the Talkshop anymore.
And more to the point, even if I hadn’t done what Joel did, my practice is to never post at or even visit sites like RealClimate, Tamino’s, and now Tallbloke’s Talkshop, places that ban and censor scientific views. I don’t want to be responsible for their page views counter to go up by even one. Banning and censorship are anathema to me, and I protest them in the only way I can. I leave them behind to discuss their ideas in their now cleansed, peaceful, sanitized, and intellectually sterile echo chamber, free from those pesky contrary views … and I invite others to vote with their feet as well.
But I digress, my point is that passions are running high on this topic, so let’s see if we can keep the discussion at least relatively chill …
TO CONCLUDE: I’m interested in people who can either show that my proof is wrong, or who will give us your elevator speech about the science underlying either N&K or Jelbring’s theory. No new theories need apply, we have enough for this post. And no long complicated explanations, please. I have boiled the greenhouse effect down to four sentences. See if you can match that regarding the N&K or the Jelbring effect.
w.
NOTE 1: Here’s the thing about a planet with a transparent atmosphere. There is only one object that can radiate to space, the surface. As a result, it is constrained to emit the exact amount of radiation it absorbs. So there are no gravity/atmospheric phenomena that can change that. It cannot emit more or less than what it absorbs while staying at the same temperature, conservation of energy ensures that. This means that while the temperature can be lower than the theoretical S-B temperature, as is the case with the moon, it cannot be more than the theoretical S-B temperature. To do that it would have to radiate more than it is receiving, and that breaks the conservation of energy.
Once you have GHGs in the atmosphere, of course, some of the surface radiation can get absorbed in the atmosphere. In that case, the surface radiation is no longer constrained, and the surface is free to take up a higher temperature while the system as a whole emits the same amount of radiation to space that it absorbs.
NOTE 2: An atmosphere, even a GHG-free atmosphere, can reduce the cooling due to uneven insolation. The hottest possible average temperature for a given average level of radiation (W/m2) occurs when the heating is uniform in both time and space. If the total surface radiation remains the same (as it must with a transparent atmosphere), any variations in temperature from that uniform state will lower the average temperature. Variations include day/night temperature differences, and equator/polar differences. Since any atmosphere can reduce the size of e.g. day/night temperature swings, even a transparent GHG-free atmosphere will reduce the amount of cooling caused by the temperature swings. See here for further discussion.
But what such an atmosphere cannot do is raise the temperature beyond the theoretical maximum average temperature for that given level of incoming radiation. That’s against the law … of conservation of energy.
NOTE 3: My bible for many things climatish, including the emissivity (which is equal to the absorptivity) of common substances, is Geiger’s The Climate Near The Ground, first published sometime around the fifties when people still measured things instead of modeling them. He gives the following figures for IR emissivity at 9 to 12 microns:
Water, 0.96 Fresh snow, 0.99 Dry sand, 0.95 Wet sand, 0.96 Forest, deciduous, 0.95 Forest, conifer, 0.97 Leaves Corn, Beans, 0.94
and so on down to things like:
Mouse fur, 0.94 Glass, 0.94
You can see why the error from considering the earth as a blackbody in the IR is quite small.
I must admit, though, that I do greatly enjoy the idea of some boffin at midnight in his laboratory measuring the emissivity of common substances when he hears the snap of the mousetrap he set earlier, and he thinks, hmmm …
>>Thanks, Dr. B. But misleading? I have shown that there is no way for an IR transparent atmosphere to affect the surface temperature. What is misleading about that?
Yes, GHG’s exclusively set the surface temperature in your model. However, it is misleading because your model exacerbates the apparent impact of GHG’s in the real world. The 70% of the Earth’s surface with cloud cover, does not behave according to your model. It might be useful to model the area covered by cloud in a comparable fashion to your naked sphere. It does not seem to me that modelling cloud as a thin shell is adequate, because the surface temperature becomes the same as the cloud temperature. I’d be most interested to see you take the next step and present an enhanced model.
There are all kinds of Potential Energies that can turn into actual thermal energy.
Gravitational Potential Energy can turn into thermal energy when a object with mass enters into or falls through a gravity field.
Nuclear Potential Energy can turn into massive thermal energy when mass is converted into energy.
Chemical Potential Energy, Electric Potential Energy.
The universe is not only made up of radiation transfers between objects.
In fact, the only reason the solar forcing exists is because a great deal of mass gained thermal energy falling into the gravity field of the Sun (gravitational potential energy) and then Nuclear potential energy took over and now the Sun is putting out 63,200,000 watts/m2 of solar radiation towards us.
All kinds of strange things that we wouldn’t expect happen in real quantum physics.
” SO far, no one has provided any disconfirming evidence of SB while there is plenty (IMO) of confirming evidence(such as photos taken by infrared cameras) of it.”
Maybe use Miles Mathis’ derivation of SB? Might be some entertainment value in that…
http://milesmathis.com/stefan.html
“I’m sorry to say that I do not understand your post. My question was referring to the fact that the Earth as a whole emits ~240W/m2 while the surface emits~390W/m2. From the POV of my question, it doesn’t matter whether the 390w/m2 comes from the sun or a giant bonfire or gravitational collapse of the planet or microscopic amounts of pressure induced nuclear fusion or whatever. In the case of a Nitrogen atmosphere if the surface emits 390W/m2, then the planet as a whole should based on current theory emit 390W/m2. Since this is not what we observe in the real world, we can either explain what is different about the actual atmosphere compared to a nitrogen one of the same mass and pressure or we can explain how a nitrogen atmosphere would actually produce the difference in emission btw the surface and the planet as a whole. If we can’t do either, then we do not have a useful hypothesis IMO.”
Well the surface of earth doesn’t emit 390 w/m/2, nor does it radiate 240 W/m/2 at top of atmosphere. These are models.
The surface emits varying amounts of energy- depending on where and when.
15 C or 288 K can emit 390 watts. My temperature outside is not 15 C.
Now, suppose I lived somewhere where it was 15 C, and suppose it was night time and my driveway was 15 C and remained around 15 C for an hour, Do you think it would be producing 390 watts of energy per second per square meter- or emit 3600 times 390 watts per hour?
What is the difference in term power produced between my 15 C driveway and if my floor, walls and ceiling were also about 15 C?
Could I not say that my walls are kept warm due to air temperature? Can not also say the driveway is also kept warm from air temperature?
DeWitt Payne says:
January 16, 2012 at 4:08 pm
“Science of Doom has lots more detail, specifically in this article.”
DeWitt – You appear to have commented there a lot, and to be fairly knowledgeable, so maybe you can answer my question about this article. I fear the thread there has gone stale, and I doubt I can get an answer as nobody will be looking any longer.
As can be seen in Figure 4, the emissivity drops off precipitously as the observation angle approaches 90 deg. Not surprising, of course, but SB is calculated assuming a completely clear field of view, i.e., the surface is completely smooth, so the emissions are roughly uniform over the overarching hemisphere. Experience tells me that a smooth and polished black panel will reflect a lot more light than one with a rough surface. I would expect the same would be the case with emissions, which is, after all, essentially 1/2 of the reflection process.
And, Figure 4 appears to back this impression up. So, it seems the proper equivalent emissivity for a body with a rough surface should, in fact, be scaled by the area under these curves.
When I integrate, for example, the function in Figure 4a over the hemisphere, I get something like 0.8 as the total effective emissivity. If I assumed that the Earth were all ocean with this as the effective emissivity, that takes it down from equivalent radiated energy of 390 W/m^2 to 312 W/m^2.
Now, if I suppose that these were pretty calm waters, and that the lowered effective emissivity were more on the order of maybe 0.7 worldwide, that would get me down to 273 W/m^2. Only 33 W/m^2 to go to reach the incoming 240 W/m^2. Actually, if I take the incoming to be distributed across a sphere 100 km higher than the surface, that becomes 248 W/m^2 (ratio of radii squared), so that takes me down to 25 W/m^2 to account for.
I suspect GHG warming does account for at least some of the budget, so give or take a little here or there, and there are other things to consider, but I do not want to detract from my point here. The point is, the putative GHG warming effect could be, at the very least, a lot less than commonly believed.
So, the question is, have climate folks actually factored the losses due to surface roughness into their estimates? Or, have they perhaps grossly overestimated total emissions of non-ideal bodies?
There are other considerations, e.g., does the morphology of emissions spectra change with observation angle as well? Experience with optical gratings suggests to me that the spacing of interfering bumps and crags could be important in determining which frequency components get out, and which get reabsorbed. And, so on. But, perhaps this will do to go on for now.
Dear Willis Eschenbach ,
Karl Zeller and I have been working on preparing a reply to your questions, which have also been asked by a number of other people. Our reply will be in two parts. Part 1 will become available by Wed (Jan 18). Part 2 will arrive a week or so later … Part 1 focuses on the magnitude of the GH effect, as this topic seems to be the crux for most people including yourself. You will learn (and see physical proof of) that our atmosphere actually raises the surface temperature not by 33K, but by well over 100K! Now, think what are the implications of this fact alone for the current GH theory? Do you know what’s the total amount of GH gases in the atmosphere as a percent of total atmospheric mass? How likely is that handful of gases can raise the near-surface temperature by 133K through ‘back radiation’?
About the ‘elevator speech’ – that was given in our first paper! However, you apparently did not get it. So, it will take far more explanation to convey the basic idea, which we will try to do in Part 2 of our reply.
In the mean time, if I may offer an advice, please try to find some good old textbook on classical thermodynamics preferably published before 1985, and read about the implications of the Gas Law, specifically what is the role of pressure in isobaric processes. That would be a time well spent for you!
Thank you.
– Ned
“So, it seems the proper equivalent emissivity for a body with a rough surface should, in fact, be scaled by the area under these curves.”
Scaled by the sine of the observation angle to get the correct incremental area on the hemisphere.
Willis,
The more I think on it… the more I think that your clear IR transparent atmosphere actually cools the surface of your theoretical planet.
Consider….
Although N2 and O2 are transparent in the IR spectrum… the DO still radiate if at a temperature above 0 kelvin. Granted, they don’t radiate in the IR spectrum… but energy out is still energy out… regardless of what frequency it occurs.
So, your atmosphere acquires heat energy from the surface via conduction, and propagates it throughout the atmosphere via convection, and finally radiates it out to space via SB radiation. Albeit, again, not at IR frequencies.
Both your surface, and your atmosphere are now radiating.
Thus, because of conservation of energy, the surface must now be radiating less than it would without the atmosphere. This is understandable since it gave up some of its energy to the atmosphere.
Another way to look at it is that the non-GH gasses in the atmosphere are sucking energy from the surface… cooling it… much in the same way that sweat sucks heat from our skin (via phase change).
I don’t know if this helps anyone’s argument.
One thing is clear though… focusing on only what’s going on in the IR spectrum causes one to miss what’s really going on. We need to focus on radiative energy transfer… regardless of the frequency. Although N2 and O2 are poor absorbers in the IR spectrum and thus poor IR radiators, they are certainly not poor radiators across all frequencies.
Also, I contend that my theoretical bottle of N2 or O2 gas would loss temperature pretty much as rapidly as any other gas… again just not radiating in the IR spectrum.
-Anton
Willis Eschenbach says in response 1/16 3:16pm (fine turnaround time with all these conversations & I will risk not restating my standing elevator speech):
“If any mechanism increases the surface temperature with a transparent GHG-free atmosphere, the surface will be radiating more to space than it is absorbing, and that is a violation of conservation of energy.”
Right, to preserve conservation of energy, the surface temperature with any mechanism ADDED to the black body by Willis (a transparent GHG-free atmosphere) (or any added by me) means the planet surface CANNOT be thermally radiating to space more than it is absorbing, nature needs a rescue that must be provided by any mechanism added to BB. Willis added this particular second mechanism to the planetary black body, not me. I have not added any mechanism.
This particular second mechanism added by Willis brings into the nature of the system thermal conduction which did not operate in Willis’ one mechanism black body thermally radiating to space. This particular two mechanism surface temperature is now both thermally radiating AND thermally conducting then radiating to space just right to preserve energy conservation, nature is rescued. These two mechanisms are from Willis. No two mechanism system energy conservation violation does or need arise.
Details:
Top post starts w/one mechanism: planetary black body with gravity thermally radiating to space; no thermal conduction operates.
Willis’ top quote verbatim: “Let me call the “theoretical S-B temperature” the temperature that an evenly heated blackbody planet in outer space would have for a given level of incoming radiation in W/m2.”
Planet equilibrium temp. T established on physical details. No violation.
———————————————
Any mechanism is added by Willis: in particular a transparent GHG-free atmosphere second mechanism is added to the same one mechanism planetary black body.
Willis top quote verbatim: “Now suppose we add an atmosphere to the planet, a transparent GHG-free atmosphere.”
Two mechanisms now: 1) a planetary black body surface thermally radiates to space + 2) transparent GHG-free atmosphere thermally conducts and then thermally radiates to space at TOA.
As Willis quote above states: this planet surface cannot be radiating more to space than it is absorbing so it doesn’t (i.e. the BB surface radiates exactly what it receives in the presence of Willis’ added thermal conduction which comes to nature’s rescue).
Same planet has equilibrium temp. near surface established higher T + delta T due to second mechanism added by Willis: the ideal gas KE from a transparent GHG-free atmosphere introduced in presence of gravity so nature reveals operation of gravity, the ideal gas law AND thermal conduction to us – all at once, & at least ideally, permanently w/sun & no loss of mass in that atmosphere mechanism. No energy conservation violation thus need arise, energy in = energy out as long as sun & gravity lasts with two mechanisms at equilibrium T + delta T.
Fun & interesting discussion Willis et. al., though Willis appears to me might be growing weary from the size of it. Just my observation from reading a blog, could be wrong.
PS: Apologize about cap.s used, I am not screaming – just don’t know how to emphasize w/underline or bold on this site.
Phil. :
January 16, 2012 at 12:43 pm
Absorption and emission are symmetric conditions quantum mechanically. If a line exists it can be excited, meaning it can absorb the same line. The ambient electromagnetic spectrum is a continuum as the black body radiation shows (frequency is 1/wavelength). The high tail of the kinetic energy distribution always has enough energy to excite and ionize some of the gas during a collision , though it would be quite rare.
Argon, as all molecules will also have the continuum radiation arising from the collisions distorting its field and creating continuum levels that can absorb and emit radiation.
There is no physical bulk matter that will not radiate as a black body.
There seem to be a lot of people who do not understand the concept of a thought experiment. It does not have to be physically plausible! Especially when the point is that it is part of a proof by contradiction, as the whole point of such a proof is to show that an impossible conclusion has resulted and therefore the starting point must have been incorrect.
So those saying that Willis’s model should be improved, e.g. because all substances interact with electromagnetic radiation, and so must absorb at some frequency, even an inert gas like Argon, are correct, but have missed the point completely. The completely transparent atmosphere is not Willis’s invention – it is implicit in the models he is criticising. These models claim that all of the GHE can be explained without any mention at all of absorption or emission of radiation by the atmosphere. It follows that their theories should be true for an atmosphere which is completely transparent. Perhaps the authors of these theories do not realise that they have built this into their model, but they have. So it is legitimate to ask how a completely transparent atmosphere would behave. Willis has given the answer, and shown that the ‘it’s all due to gravity’ models are nonsense.
PS to Trick above – a transparent atmosphere does not radiate anywhere, even at TOA.
Bart says:
January 16, 2012 at 4:54 pm
““Personally, I doubt that there is any substantial effect here, as this would be easy to measure and would make anyone who finds contradictory evidence pretty famous.”
Well, hell, let’s just end scientific inquiry altogether, as there’s nothing left to discover. If it hadn’t been, lots of people could be famous. Since they aren’t, there’s nothing left to discover. QED.”
Here’s a reality check for you: Can you point to a **single** piece of evidence that supports your position? I submit that every day there are thousands if not millions of tests of the SB relationship. You want to say that those tests don’t mean anything because they don’t meet your (self-imposed) standards. I submit that there is no reason to believe that more tests will only find what has already been found. I’m quite sure that the theory of gravity hasn’t been tested in all the different environments you think SB needs to be tested, but most folks are pretty confident in that theory even so. Why?: because no one has been able to produce any evidence of real world occurences that contradict the theory.
If you are really interested in scientific inquiry into the SB relationship – here is a pretty good place to start IMO:
http://www.cce.ufes.br/jair/web/stefBoltz.pdf
Cheers, 🙂
@Bart
I see you understand my major point: A non-GHG atmosphere will emit energy, apart from the black body surface. The total energy entering will not all leave from the surface as IR. Part will radiate from the atmosphere because it will heat up.
@Phil
>>To repeat, just because a gas does not absorb IR radiation does not mean it will not emit IR and other radiation.
>Repetition of a fallacy doesn’t make it true, the Physical Law that contradicts your statement is known as Kirchoff’s law. Emissivity at a wavelength is equal to the absorptivity at that wavelength.
I refer you to the explanation given at length above by George E Smith. I have no need to repeat its truths.
Anna V also states very clearly the point I was trying to make. It is incorrect to say that a black body planet with a GHG-free atmosphere must emit all its energy by IR radiation from the surface, and equally untrue that the atmosphere will not increase in temperature, the same regarding the absence of thermals and wind.
With regards to Willis’ investigation, the heavier and the deeper the atmosphere, the greater the insulating effect (with nod to the argument that gases vary in conduction coefficients with pressure). If gravity were to increase, the efficiency of conduction from the surface to the atmosphere would increase (directly) in efficiency and the proportion emitted from the non-GHG atmosphere into space would increase as the molecular collisions would be more frequent and more enegetic.
There is no such thing as a non-GHG atmosphere that does not emit radiation so the thought experiment is not going far. I agree with Willis’ earlier calculation that the surface might well be hotter if all GHG’s were removed and the ‘non-GHG’s’ retained because evaporated/condensed water is an efficient working (heat transport) fluid and superb IR radiator.
Regards
A radio HAM
Crispin,
“There is no such thing as a non-GHG atmosphere that does not emit radiation so the thought experiment is not going far.”
On the contrary, the thought experiment shows precisely what it is supposed to, namely that a model in which the radiative properties of the atmosphere do not exist, cannot be correct. So, instead of criticising Willis’s thought experiment, you should be asking Nikolov and Zeller why they omitted these factors.
shawnhet says:
January 16, 2012 at 10:15 pm
“I submit that every day there are thousands if not millions of tests of the SB relationship.”
I have not questioned the SB relationship at all. I have questioned the shallow manner in which it is being applied. The difference between us appears to be, I know how it is derived, and the conditions upon which its successful application depends. You, however… apparently not so much.
gbaikie says:
January 16, 2012 at 7:05 pm
“Could I not say that my walls are kept warm due to air temperature? Can not also say the driveway is also kept warm from air temperature?”
The driveway can be warmed by the air, but it can only do so by transferring heat into it. In the absence of a GHE it cannot increase the amount of heat in the Earth system at any given time. OTOH, a GHE can increase the amount of heat in the Earth system at any given time by causing some IR radiation to be absorbed and re-emitted multiple times before the radiation finally gets high enough to radiate to space.
Cheers, 🙂
DeWitt Payne says:
January 16, 2012 at 4:37 pm
“You will need to do more than make an assertion about the Laplacian in spherical geometry to prove that an isothermal atmosphere is unstable. The atmosphere is a very thin shell around the planet and the planar approximation is quite good.”
No, I really don’t. Unstable is unstable. It does not matter if it is fast or slow, eventually the unstable state will find a way to transition to a stable one. And, the discussion is about a system in “steady state”.
In physics – all topics require being aware of the frame of reference
With that in mind here is an ‘elevator scenario’
1st scenario – no atmosphere
Ok, the Sun just turned on:
Our black body starts to heat up
as the temp increases the black body emits energy back out
equilibrium is achieved
life is happy
2nd scenario – add an atmosphere
Ok, the Sun just turned on
Our black body starts to heat up
There is a delay in the heat getting back to space because of the atmosphere.
as the temp increases the black body which includes this atmosphere emits energy
equilibrium is achieved
life is happy
But – note the delay. If you agree this start up scenario introduces a delay in how soon equilibrium is achieved then you’ll recognize there is a lapse rate and delay in the conduction of heat back to space caused by the atmosphere.
That’s my attempt at a simple elevator type thought.
The rest is more musings on the above.
The total frame of reference will make both scenarios the same looking at the whole planetary system. But if you narrow the frame of reference to just the surface of the planet where there is always a delay taking place you’ll see a local rise in temps near the surface and above this as you head towards space a cooler area. The net of the whole system is the same but there is a differential in temps in the atmosphere depending on what altitude you measure the temps.
ie: Warmer by the surface, cooler as you approach space.
If there is a delay in the energy getting into space as the planet is first being heated by the sun creating a warmer and cooler zone in the atmosphere, then this difference will persist.
If there is no delay in the initial energy getting into space as the planet is first being heated by the sun then your original premise is correct.
The greater the pressure of the atmosphere the greater this initial delay. Also the greater the local frame of reference of temperature will be from low altitudes to high altitudes, though the system average temp – surface and air will be at the constant for a planet with no atmosphere.
So, is there a delay in the initial heating of a black body if there is an atmosphere? Does the presence of said atmosphere create a gradient of measurable temps that are highest near the surface and get cooler as you move towards space? Yet the cooler temps as you go higher do not emit as much as the surface does and conduction is the major player here in both the delay and the local apparent increase in temps near the surface.
As any pilot knows the surface of the earth is too warm and as you go up it’s too cold. But the average atmospheric temperature plus surface radiation will be the same as a black body with no atmosphere. It simply has to be. Also the cold area offsets the warm area and as an earlier poster says this equilibrium point is about 5k up. So just measure in the atmosphere where the expected S-B temp is and you’ll have warming below and cooling above netting to no change. But if the local frame of reference is not the whole system but just a small area by the surface, since above 5k is cooler, that below 5k area must be warmer or equilibrium will not be at the expected value for the whole system.
Lapse rate, delays, high and low temps as altitude changes in an atmosphere are what the N-Z theory seems to be about. Hopefully the above helps to potentially describe where they are coming from.
I can see this thread is slowing to a snails’ pace. Thank goodness. Time for an elevator speech on my humble observations of the exhausting few days of following the entertainment. Since it is an elevator speech, I shall not be mentioning names. You know who you are. Nor will I get technical. We have had enough of that.
Here goes:
1. The majority, but certainly not all, of the posters seem seriously confused about the difference between the concepts of temperature and heat (or energy).
2. A great many posters are seriously hazy as to how adiabatic pressure vs temperature works in an atmosphere, particularly about the ‘need’ for convection for it to work. Think isothermal vs isentropic
3. The confusion about radiation (or not) from transparent atmosphere at above 0K is epic. The adamant to-the-death defense of the stance of the ‘not’ was a sight to behold, especially but not confined to the main poster.
4. The pervasive and abysmal ignorance on just the above three points so dominated the discourse that the thread is probably 10x as long as it needs to be. 50% of the remainder was wasted on personal and unbecoming bitchiness that would give my youngest daughters’ school classmates a run for their money. (And that is saying a lot)
5. One comes away with a feeling of disbelief that so many individual posters who clearly believe they know a lot and can swamp us with technicality still err on basic issues.
My sincere thanks to the few voices in the wilderness who get the basics right and who thereby refreshed my own very rusty memory. I also stand deliciously refreshed in my scepticism of majority opinion out there.
Gabriel van den Bergh, signing off… (phew)
jimmi_the_dalek says:
January 16, 2012 at 9:20 pm
There seem to be a lot of people who do not understand the concept of a thought experiment. It does not have to be physically plausible!
A thought experiment must not contradict existing data. It is a form of a “theoretical model”. They must not contradict physical data. If they do, they are science fiction, not physics models. Particularly if they are used to a proof by contradiction (Reductio ad absurdum). Conservation of energy is a basic physical law.
PS to Trick above – a transparent atmosphere does not radiate anywhere, even at TOA.
only in science fiction.
I miss one point in this discussion: reflexion. Every electromagnetic wave -and IR is such an EM-wave- can be reflected, and we know that it is happen because of such things as radio, especially longwave, fata morganas etc. Each boundary layer, especially with relatively large discrepancies between the strata, is capable to reflect radiation.
All radiative interacting substances act with three relevant parameters:
– absorption
– transmission
– reflexion
Actually, none of those is 0. Therefore it is necessary to know the ratio between reflection and absorption.
If one knows the transmission one can answer the question: how much of the downwelling radiation is reflected? This is relatively easy to find out – as far as we have the transmission ratio (see below).
Idealized one can assume that absorbed energy is re-emitted upwards and downwards with the same ratio, means 50% each. Considering that reflected goes 100% down and absorbed energy goes 50% down resp. 50% up, one has to take the difference between up and down radiation and gets the amount of reflected energy.
To find out the effects of GHG we have to consider that it needs 2 times of the absorbed energy to equal the reflected energy. This leads to the following:
If
– 2x absorbed > reflected ==> warmer
– 2x absorbed = reflected ==> no difference
– 2x absorbed cooler
To calculate the amounts of transmitted energy and therewith the ratio contains a problem. It is quite difficult to number the actual amount because it contains not only the atmospheric window (40W/m²) but also the unsaturated absorption bands of GHG (at least difficult for me, perhaps someone can help).
The higher the transmitted energy the lower the absorbed and re-emitted part of energy and with this the higher the part will be reflected.
– 2x absorbed cooler
Actually it has to be:
2x absorbed cooler.
I would be apreciated if someone would consider this and change it.
Thanks.
It appears that many people have been confused about the fact that most greenhouse effect calculations are based on average energy flow rates–usually measured in watts per square meter. Technically, power in watts represents the energy flow rate in joules per second. These calculations are based on steady-state conservation of radiant energy requirements. To make these values palpable, they are often represented by the uniform temperature that the Stefan-Boltzmann formula says would produce that same average energy flow from a presumed level, flat surface on the Earth.
Conservation of energy says that the Earth must radiate over its whole surface the same energy flow that it is absorbing (not reflecting) from the disk of intercepted solar radiation. This is an average escaping LWIR energy observed at the top of the atmosphere and it is independent of any greenhouse effect in the atmosphere below.
The nominal value for this required flow is usually stated as 239 or 240 W/m². If the surface were emitting energy at a higher average rate, say 396 W/m², then something must be extracting 156 W/m² from the *radiant* energy flow going up in the atmosphere and returning it back to the ground. Only greenhouse gases can perform that function on a continuous basis.
– 2x absorbed ‹ reflected ==> cooler
Sorry again.
Paul Dennis says:
January 16, 2012 at 1:22 am
Thanks, Paul. I’ll have to think about that some more. The oddest statement is that
Seems paradoxical to me, all right. I’ll have to ponder some more.
Fortunately, it makes no difference to my proof above.
Many thanks,
w.