Guest Post by Ira Glickstein
This series began with a mechanical analogy for the Atmospheric “Greenhouse Effect” and progressed a bit more deeply into Atmospheric Windows and Emission Spectra. In this posting, we consider the interaction between air molecules, including Nitrogen (N2), Oxygen (O2), Water Vapor (H2O) and Carbon Dioxide (CO2), with Photons of various wavelengths. This may help us visualize how energy, in the form of Photons radiated by the Sun and the Surface of the Earth, is absorbed and re-emited by Atmospheric molecules. 
DESCRIPTION OF THE GRAPHIC
The animated graphic has eight frames, as indicated by the counter in the lower right corner. Molecules are symbolized by letter pairs or triplets and Photons by ovals and arrows. The view is of a small portion of the cloud-free Atmosphere. (Thanks to WUWT commenter davidmhoffer for some of the ideas incorporated in this graphic.)
- During the daytime, Solar energy enters the Atmosphere in the form of Photons at wavelengths from about 0.1μ (micron – millionth of a meter) to 4μ, which is called “shortwave” radiation and is represented as ~1/2μ and symbolized as orange ovals. Most of this energy gets a free pass through the cloud-free Atmosphere. It continues down to the Surface of the Earth where some is reflected back by light areas (not shown in the animation) and where most is absorbed and warms the Surface.
- Since Earth’s temperature is well above absolute zero, both day and night, the Surface radiates Photons in all directions with the energy distributed approximately according to a “blackbody” at a given temperature. This energy is in the form of Photons at wavelengths from about 4μ to 50μ, which is called “longwave” radiation and is represented as ~7μ, ~10μ, and ~15μ and symbolized as violet, light blue, and purple ovals, respectively. The primary “greenhouse” gases (GHG) are Water Vapor (H2O) and Carbon Dioxide (CO2). The ~7μ Photon is absorbed by an H2O molecule because Water Vapor has an absorption peak in that region, the ~10μ Photon gets a free pass because neither H2O nor CO2 absorb strongly in that region, and one of the 15μ Photons gets absorbed by an H2O molecule while the other gets absorbed by a CO2 molecule because these gases have absorption peaks in that region.
- The absorbed Photons raise the energy level of their respective molecules (symbolized by red outlines).
- The energized molecules re-emit the Photons in random directions, some upwards, some downwards, and some sideways. Some of the re-emitted Photons make their way out to Space and their energy is lost there, others back down to the Surface where their energy is absorbed, further heating the Earth, and others travel through the Atmosphere for a random distance until they encounter another GHG molecule.
- This frame and the next two illustrate another way Photons are emitted, namely due to collisions between energized GHG molecules and other air molecules. As in frame (2) the Surface radiates Photons in all directions and various wavelengths.
- The Photons cause the GHG molecules to become energized and they speed up and collide with other gas molecules, energizing them. NOTE: In a gas, the molecules are in constant motion, moving in random directions at different speeds, colliding and bouncing off one another, etc. Indeed the “temperature” of a gas is something like the average speed of the molecules. In this animation, the gas molecules are fixed in position because it would be too confusing if they were all shown moving and because the speed of the Photons is so much greater than the speed of the molecules that they hardly move in the time indicated.
- The energized air molecules emit radiation at various wavelengths and in random directions, some upwards, some downwards, and some sideways. Some of the re-emitted Photons make their way out to Space and their energy is lost there, others back down to the Surface where their energy is absorbed, further heating the Earth, and others travel through the Atmosphere for a random distance until they encounter another GHG molecule.
- Having emitted the energy, the molecules cool down.
DISCUSSION
As in the other postings in this series, only radiation effects are considered because they are the key to understanding the Atmospheric “Greenhouse Effect”. I recognize that other effects are as important, and perhaps more so, in the overall heat balance of the Earth. These include clouds which reflect much of the Sun’s radiation back out to Space, and which, due to negative feedback, counteract Global Warming. Other effects include convection (wind, thunderstorms, …), precipitation (rain, snow) and conduction that are responsible for transferring energy from the Surface to the Atmosphere. It is also important to note that the Atmospheric “Greenhouse Effect” and a physical greenhouse are similar in that they both limit the rate of thermal energy flowing out of the system, but the mechanisms by which heat is retained are different. A greenhouse works primarily by preventing absorbed heat from leaving the structure through convection, i.e. sensible heat transport. The greenhouse effect heats the earth because greenhouse gases absorb outgoing radiative energy and re-emit some of it back towards earth.
That said, how does this visualization help us understand the issue of “CO2 sensitivity” which is the additional warming of the Earth Surface due to an increase in atmospheric CO2? Well, given a greater density of CO2 (and H2O) molecules in the air, there is a greater chance that a given photon will get absorbed. Stated differently, a given photon will travel a shorter distance, on average, before being absorbed by a GHG molecule and be re-emitted in a random direction, including downwards towards the Surface. That will result in more energy being recycled back to the Surface, increasing average temperatures a bit.
“If it returns to the surface and does not warm it must be totally reflected. If it is totally reflected then the surface cannot emit at that wavelength either (basic law of thermodynamics). Therefore it is not possible for radiation to be emitted from the surface, absorbed by the atmosphere and re-radiated downwards without increasing the temperature of the surface”.
My understanding is that this is not correct. As a cooler body can not warm a warmer body. Otherwise if for example a human was in a container of CO2 they would heat up rather than just cool at a slower rate. Or a human in a vacuum with a perfect radiation reflector would eventually cook to death. This surely is not possible.
So my understanding is that radiation from a colder body can not heat a warmer body. As a teacher can pass and increase knowledge of a student. And a student to a younger student. But not increase knowledge (heat) by passing it back
.
Gerge E Smith says: My impression is that there is confusion between thermal transfer between molecules (rotation, vibration etc) and radiation emission/absorption. The first depends on the thermodynamics, the second on quantum physics
I would lkie an euro for every time I’ve said this on this site and stil people continue.
Surely they can only re-emit much lower energy photons, of similar energy levels to the black-body curve at -20C.
This is a confusion between kinetic heat energy and quantum radiative energy.
Dave Springer says:
March 29, 2011 at 12:30 pm
The air is ALWAYS emitting a continuous blackbody spectrum! Everything with a temperature above absolute zero emits a continuous blackbody spectrum with a peak frequency that rises with rising temperature. The higher the peak frequency the more energy in the emission. This is where the downwelling radiation comes from and its existence is without doubt.
Of course it does not. Only a black body emits a black body spectrum. The atmosphere is not a black body. If it were a black body we would not be able to see the sun! Indeed most things are not even close to black bodies – that is why the world is colourful. Did you not see the spectral distribution looking up at the night sky that was posted about a week ago? It looked nothing like the black body curve. It was completely dominated by the greenhouse gas spectral lines as one would expect. The atmosphere is pretty transparent in the visible region and has an atmospheric window around 10 micron where there is not much absorption, so these wavelengths are absent in the downward radiation as well.
This was a great post!
Brilliant.
Very very nice presentation.
Thank you, now I will consider this in depth.
The greenhouse effect and the energy retaining effect of the oceans are different things. The atmosphere and the ocean may retain heat, but the atmospheric heat retention is infinitesimal compared to the heat retention of the oceans. The greenhouse effect changes the amount of heat that flows out of the system.
The oceans absorb the vast majority of the RADIATIVE ENERGY stiking the planet from the sun. This RADIATIVE energy leaves the planets surface by a route proportional to the density of the atmosphere (not just GHGs) and the speed of light. That’s why Stephen Wilde said what he said. ALL the energy on this planet comes from the sun ~ 99.9%. The Earth approximates to a blackbody in as much as it’s surface albedo modifys the amount of RADIATION that is reflected back into space. A blackbody cannot re-absorb radiation it has given up after equilibrium is reach. After equilibrium all radiation striking the BB is reflected away that’s why the earth and the moon cannot heat the sun by radiative reflection. After bombarding the earth with radiation for 5 billion years they are as near as damn it at BB equilibrium unless the sun’s radiative output changes.
Dave Springer says:
March 29, 2011 at 12:30 pm
You were doing fine until you said no back radiation takes place.
I was speaking very narrowly about CO2 per the drawing of Ira’s. If CO2 has at STP no emissivity then by Kirchoff’s Law it did not absorb.
Thanks Reed Coray for your clear example that works for you (and me) in the cold vacuum of space. Thanks also for agreeing with my argument that the Atmospheric “Greenhouse Effect” raises the temperature of the Surface under the conditions I stated, namely that I was not considering conduction and convection (although I also stated that they have significant effects on the Surface temperature of the Earth).
I hope I am not wasting my time or yours.
Whether or not the Atmospheric “Greenhouse Effect” is present, the effects of convection and conduction (and precipitation and so on and on) depend upon the Surface and Atmospheric temperatures, humidity, and a bunch of other things. I think we both agree they have a net cooling effect.
How could the effects of convection/conduction/precipitation more than counteract the effect of GHGs in the Atmosphere, which you agree, taken alone, would increase Surface temperatures?
Are you proposing that a warmer Surface would cause more convection/conduction/precipitation? Well, yes, I think it would! However, if these net cooling effects were greater than the warming due to the GHGs, the Surface would cool, and the increased convection/conduction/precipitation would go away. Thus, it seems to me that convection/conduction/precipitation can only moderate the effects of GHGs, not cancel them out entirely.
Inter-radiation of energy between molecules in all planetary atmospheres are random walks with an upward bias due to the curvature. The only place this does not occur is in the window where radiation can move from the surface to space directly.
Cassandra King, you should be able to see this effect. It is what further reduces the effect of that 0.039% factor you mentioned for we live on a round Earth.
Try reviewing this comment and the contained image: http://wattsupwiththat.com/2011/03/10/visualizing-the-greenhouse-effect-emission-spectra/#comment-629487
cal says:
March 29, 2011 at 12:12 pm
Cal, thank you for your response.
My argument has little if any relevance to the computation of the surface temperature of the Earth in the presence of greenhouse gases. However, it does have relevance to Ira’s statement: “That said, how does this visualization help us understand the issue of “CO2 sensitivity” which is the additional warming of the Earth Surface due to an increase in atmospheric CO2? Well, given a greater density of CO2 (and H2O) molecules in the air, there is a greater chance that a given photon will get absorbed. Stated differently, a given photon will travel a shorter distance, on average, before being absorbed by a GHG molecule and be re-emitted in a random direction, including downwards towards the Surface. That will result in more energy being recycled back to the Surface, increasing average temperatures a bit.”
In particular, his statement implies backradiation results in (a) more energy being returned to the Earth surface, and (b) an increase in average temperatures. If any situation can be constructed where (a) backradiation does NOT result in more energy being recycled back to the active object’s surface, and/or (b) backradiation does NOT increase the active object’s surface temperature, then in my opinion Ira’s statement requires additional justification.
By applying Planck’s blackbody radiation law to the surfaces of (1) an active, uniform-surface-temperature sphere and (b) a thin, co-centered, disjoint, inert, planar, uniform-surface-temperature, circular annulus, it can be shown that in the presence of object-to-object conduction, the rate of inert-object to active-object backradiation, although present, can be made less than the rate of conductive energy transfer from the active object to the inert object. This will result in a lower active-object temperature. Furthermore, even in the absence of object-to-object conduction, increasing the outer radius of the inert annulus beyond a certain point, which provides a larger surface area from which backradiation can originate, results in less backradiation, not more. It may be true that greenhouse gas backradiation warms the surface temperature of the Earth, but Ira’s statements that (a) adding more greenhouse gas will increase the amount of backradiation, and (b) that the additional backradiation will warm the surface of the Earth do not convince me. I want to see an analysis of how and to what degree conduction and convection affect the amount of backradiation received by the Earth’s surface relative to the rate of energy transfer from the Earth’s surface by these thermal transfer mechanisms. For example, wouldn’t the increase in the amount of greenhouse gas increase the rate of conductive thermal transfer and possibly convective thermal transfer from the Earth’s surface to the atmosphere? If so, which effect is dominant, and under what conditions?
cal says: March 29, 2011 at 10:12 am
“I am getting a bit depressed by the level of physics being discussed here and in some of the other web sites that we are being directed to…. It is pointless coming up with simplistic arguments to deny these facts when we have data to confirm them.”
AMEN!
As to the original post
* in (7) you say “The energized air molecules emit radiation at various wavelengths”
The emission is still by the GHGs since other molecules are notoriously poor at emitting any sort of IR.
* along with the previous point, the diagram in step 7 seems to show an O2 molecule emitting IR. This would not happen (to any significant degree).
* Most importantly, you miss one major way that molecules can get the energy to emit IR — collisions with other molecules. Just as GHG molecules that have absorbed extra energy from IR photons can pass that energy on to other molecules, other molecules can collide with GHG molecules and give them extra energy from the collision that can then be emitted as IR photons.
cal says:
March 29, 2011 at 11:41 am
If it returns to the surface and does not warm it must be totally reflected. If it is totally reflected then the surface cannot emit at that wavelength either (basic law of thermodynamics). Therefore it is not possible for radiation to be emitted from the surface, absorbed by the atmosphere and re-radiated downwards without increasing the temperature of the surface.
Cal, I have to disagree. Consider a spherical active Earth surrounded by an “atmosphere” comprised of co-centered, thin, blackbody-surface (both sides), spherical shell with a vacuum filling the space between the Earth’s surface and inner surface of the shell. I know this isn’t a gaseous atmosphere, but in the sense that the shell surrounds the Earth, I will take license and call it an atmosphere. In isolation, the Earth’s surface temperature will be (a) directly proportional to the fourth root of the Earth’s internal rate of energy generation and (b) inversely proportional to the square root of the Earth radius. No backradiation exists for the Earth in isolation.
When the shell is added, because in steady state the shell must radiate to space the energy generated internal to the Earth, the steady-state temperature of the shell (for a thin shell, the inner and outer shell surface temperatures will be very near the same) will be directly proportional to (a) the fourth root of the Earth’s internal rate of energy generation and (b) inversely proportional to the square root of the shell radius. Backradiation (radiation from the inner shell surface to the Earth) will exist. Since the radius of the shell is greater than the radius of the Earth, the shell’s surface temperature will be lower than the Earth surface temperature in isolation. If a thermal conduction path is provided from the Earth to the shell and if that path supports a rate of energy transfer greater than the radiative rate of energy transfer from the shell’s inner surface to the Earth, the Earth’s temperature in the presence of the shell with conduction will be lower than (a) the Earth’s temperature in the presence of the shell without conduction, and (b) the Earth’s temperature in absence of the shell. Since radiation is being emitted from the active object (the Earth) and backradiation from the inert object (the shell/atmosphere) exists whenever the shell is present, how can you claim backradiation from the shell/atmosphere must warm the surface temperature of the active object?
Very clever Reed Coray! I have to agree that the shell will be at least a little cooler than the Earth Surface because it has a larger surface area. Given a nearly 100% conduction path (such as many metal struts from the Earth Surface to the shell), the shell could be a bit cooler than the Earth and more than compensate for the warming due to the “Greenhouse Effect”.
Great theory, however there are at least three issues: 1) The small difference in surface area, 2) The large temperature increase due to the Atmospheric “Greenhouse Effect”, and 3) Convection/conduction/precipitation are not anywhere near 100% effective at transfering thermal energy from the Surface to the Atmosphere. Let us address each in turn:
1 – If the shell is at an altitude similar to the effective altitude of the Atmosphere, which is a teeny tiny fraction (less that 1/1000) of the radius of the Earth, the shell’s surface area will be almost the same as the Surface area of the Earth, so the supposed temperature difference will be miniscule.
2 – The effect of “Greenhouse” warming of the Earth is over 30ºC, which is many, many times the maximum possible temperature difference due to (1).
3- Even if (1) was as large as 30ºC, the combined sum of convection/conduction/precipitation would fail to transfer anywhere near 100% from the Surface to your shell.
Nice try though and THANKS for getting me thinking.
Gravity is a force that is constantly pressurizing the atmosphere. Consider a warmed parcel of air at the surface. It will rise, no? When it rises, it eventually cools. When it cools and is pulled to the surface by gravity, its temperature increases because it is compressed.
The constant compression of atmosphere by gravity results in higher pressure, density and temperature at the surface. No GHG’s are necessary for this..
Reed Coray says: (in reply to my reply)
March 29, 2011 at 2:44 pm
…………. If any situation can be constructed where (a) backradiation does NOT result in more energy being recycled back to the active object’s surface, and/or (b) backradiation does NOT increase the active object’s surface temperature, then in my opinion Ira’s statement requires additional justification. ………It may be true that greenhouse gas backradiation warms the surface temperature of the Earth, but Ira’s statements that (a) adding more greenhouse gas will increase the amount of backradiation, and (b) that the additional backradiation will warm the surface of the Earth do not convince me. I want to see an analysis of how and to what degree conduction and convection affect the amount of backradiation received by the Earth’s surface relative to the rate of energy transfer from the Earth’s surface by these thermal transfer mechanisms. For example, wouldn’t the increase in the amount of greenhouse gas increase the rate of conductive thermal transfer and possibly convective thermal transfer from the Earth’s surface to the atmosphere? If so, which effect is dominant, and under what conditions?
————————————–
Reed, I think it is totally reasonable to question whether there is a limit to the impact any change can have and whether there are compensating effects. Almost all natural effects have a limit and negative feedbacks. That is why the earth is ruled by cycles and, for example, does not get permanently hot or permanently cold. The greenhouse effect is logarithmic so we know that without positive feedback one has to double the concentration to get a 0.7C temperature rise and double again to get another 0.7C. Nothing to get concerned about. That is why positive feedback has to be postulated in order to scare us. With such small effects one has a duty to look at all other small effects that might create negative feedbacks which might partially compensate or even overcompensate and drive the temperature in the opposite direction as CO2 increases. You suggest this might be possible and while I do not follow your reasoning as to the specific mechanism I entirely agree that this is possible. So while I am convinced that back radiation warms the surface I am not convinced that further increases in CO2 will warm the surface further. I see these as two entirely different questions and is the reason why I believe sceptics should focus on this second question and not the first.
You might be interested in one possibility that I raised (in person) directly with the UK met office. I have never had a satisfactory answer even though it was repeatedly promised. As you will probably be aware CO2 is the most significant molecule involved in the COOLING of the atmosphere. It radiates most of the energy from the thermosphere and stratosphere and together with H2O radiates almost all the energy from the top of the troposphere and tropopause. H2O is the dominant source of radiation from the mid troposphere and of course the surface radiates directly to space, mainly through the atmospheric window around 10 micron.
So clearly there is the potential for a negative feedback through increased cooling as the concentration of CO2 increases. Which effect dominates? I believe the physics is too complicate to work this out. To find out the answer we have to do something outrageous. We have to measure what is actually happening!
We need answers to questions like: what is happening to the position of the tropopause? what is happening to the temperature in the stratosphere immediately above the tropopause? If the tropopause and lower stratosphere are cooling then we might expect the surface to continue to warm but if there is no change to the tropopause or there is warming then (perhaps non intuitively) this means more radiation to space and a lower surface temperature. A couple of years ago there was a report of a measured increase in the altitude of the tropopause and implied cooling but since then it has gone very quiet, so I suspect the measurements are not yet providing the “right” answer!!
Ian W says:
The water vapor feedback is now extremely well-verified, especially over timescales of months to a few years. See http://www.sciencemag.org/content/310/5749/841.abstract and http://www.sciencemag.org/content/323/5917/1020.summary
Amplification in the tropical troposphere (the so-called “hot spot”) is also well-verified over these timescales. Over the multidecadal timescales, the data is simply too uncertainty to reach any definitive conclusions but it is difficult to imagine mechanisms by which the physics responsible for this would break down on these timescales without also breaking down on shorter timescales.
Dave Springer says:
The only way that radiation escapes to space is by stuff radiating and the amount of radiation that stuff emits is determined by the temperature. Hence, your statement amounts to the hypothesis that the “hot spot” ought to be more pronounced, not less pronounced, than the models predict.
The models already take into account the negative feedback due to the lapse rate, which basically seems to be what you’re describing. But a literal interpretation of the claim that the hot spot is missing would be that the models are including a negative feedback that does not exist.
Except that the satellite data seem to show otherwise, as I noted above.
If that’s the best, I can’t imagine what the worst looks like! Miskolczi’s paper is basically nonsense with lots of extremely strange things like misapplying the virial theorem.
I agree with Michael Larkin that the animation was much too fast. If you right-click on the picture and save it and open it in Irfanview you can save it as eight separate pictures and then move forward and backwards at leisure (Options – Extract all frames).
BigWaveDave says:
Your notion doesn’t even satisfy the 1st Law of Thermodynamics! In the absence of a greenhouse effect, the surface temperature of the earth is set by energy balance considerations. So, unless you are proposing a large source of energy…e.g., that the earth’s atmosphere is undergoing continual gravitational collapse, which would certainly be a novel hypothesis…your notion is completely in violation of known laws of physics.
bananabender says:
March 29, 2011 at 12:41 am
The Ideal Gas Law PV=nRT quite accurately predicts the atmospheric temperature of Earth, Mars, Venus and Titan (at all altitudes) based on a simple pressure effect. Why add the unnecessary complication of the highly dubious Greenhouse Effect to an elegant and simple solution?
You are wrong. John Tyndall showed that you are wrong in 1859, and his explanation of why the earth is as warm as it is has been accepted by scientists ever since. Even Fourier in 1829 knew you were wrong, but it was Tyndall who showed it conclusively.
Two main mistakes as pointed out above.
1. Absorbing by CO2 at 15 microns does not speed up the molecule, it raises its vibration state, and may change its rotation state (15-micron side-bands).
2. Photons are not emitted by molecules other than GHGs and not at wavelengths other than those where they have spectral bands.
Other than that, fine.
Joel Shore says:
March 29, 2011 at 4:51 pm
Your notion doesn’t even satisfy the 1st Law of Thermodynamics! In the absence of a greenhouse effect, the surface temperature of the earth is set by energy balance considerations. So, unless you are proposing a large source of energy…e.g., that the earth’s atmosphere is undergoing continual gravitational collapse, which would certainly be a novel hypothesis…your notion is completely in violation of known laws of physics.
You are mistaken. You can’t ignore that gravity is a force, and that a gas is compressible, and will increase in temperature as it is compressed. Unlike the GHG hypothesis, these are physical phenomena that are measurable and reproducible.
“”””” cal says:
March 29, 2011 at 10:12 am
I am getting a bit depressed by the level of physics being discussed here and in some of the other web sites that we are being directed to. I am beginning to wonder if there is a strategy amongst the warmers to refute the greenhouse effect using bogus physics in order to quote these arguments, say how stupid they are, and thus justify the dismissal of all sceptic arguments as unscientific. Or I might just be paranoid!
There are serious problems with the quantification of the greenhouse effect. There is a serious doubt about feedbacks. There is a serious problem that the “fingerprint” of an enhanced greenhouse effect cannot be identified.
But there is no doubt that the atmosphere absorbs radiation emitted by the earth and eventually radiates it to space at a higher altitude which, being at a lower temperature, means a smaller energy loss. That reduction has to be compensated for by increased radiation losses elsewhere and that means a warmer surface. “””””
Well there is one thing seriously wrong with your thesis, cal.
The earth’s surface is mostly hotter than the air is at altitude. Therefore the surface emits at a higher emission level than the cooler atmosphere, and moreover it does so in a generally higher frequency (lower wavelength range; per wien’s Displacement Law.
So the very hottest desert surfaces, are emitting plenty of radiation that goes right on by the CO2 15 micron absorption band right out into space unimpeded by CO2. And as you get higher, and the atmosphere gets colder and less dense, the absorption bandwidth of the 15 micorn CO2 band keeps getting narrower; each and every one of the high resolution lines in the CO2 band keeps get less broadened by doppler, and collisions, as you go up in the atmosphere, so it keeps on absorbing an even lower fraction of the surface emitted radiation, and escape gets easier, as you go higher. So you are not dependent on energy being transported to the highest least dense, and coldest upper reach4es of the atmospehre, and then expecting that material to radiate the entire heat load of the planet.
And if you go in the opposite direction (atmospheric emissions are isotropic, so only half of it goes down, the downward path (that “back radiation thing”) sees a continuously warming, and denser atmosphere so the CO2 absorption spectrum gets more and more opaque for the downward radiation, instead of more and more transparent for the upward escape path.
So the earth des not sit at some BB Temperature of 255 K due to some high altitude evanescent layer of colder rarified atmosphere. Certainly the energy borne aloft as heat by conduction, convection, and evaporation (latent heat) must eventually be radiated by higher altitude gases; but the very ground itself, is making a significant direct contribution to the radiative cooling that augments the other (thermal) processes.
The earth is anything but Isothermal, and we should not expect it to radiate some isothermal radiation spectrum.
BigWaveDave says:
I am well-aware that gravity is a force and that gases are compressible. I, and other atmospheric and climate physicists are also aware of the constraints on lapse rates set by the decrease of pressure with height. However, that does not allow you to violate the Laws of Thermodynamics at will. And, these Laws tell us that the surface temperature of an IR-transparent atmosphere will go toward a steady-state value determined by the condition that the radiative emission balance the radiation absorbed from the sun (in the absence of any other significant energy source).
Harold Pierce Jr says – – –
Classic error in thinking and the modeling. The concept that once the CO2 molecule “absorbs” the IR, and becomes vibrationally excited, it “losses” that energy to the O2 and N2, and thus “traps” the energy in the atmosphere.
NOT TRUE! There is a distribution of energies of the ensemble of molecules. There is EXCHANGE. Therefore, collisions between O2 and N2 molecules on the “high end” of the distributed energy, LOSE that translational kinetic energy to CO2 and H2O molecules.
WHICH, can…with significant probability, re-emit an IR photon.
That’s why the REAL question here is what is the “optical transparency” of the ensemble of the atmosphere, and has the increased CO2 since WWII changed that number significantly.
Studying the work of Miskolczi, Ferenc M. 2010. “THE STABLE STATIONARY VALUE OF THE EARTH’S GLOBAL AVERAGE ATMOSPHERIC PLANCK-WEIGHTED GREENHOUSE-GAS OPTICAL THICKNESS”, Energy and Environment, 21, 243-262 , indicates that this is the case. I’m well aware of the critics of Miskolczi’s work. I’m also aware that based on “empirical observations” up to 1942, Dr. Elsasser came to the same conclusion as Miskolczi, and neglects CO2 in his “general radiation chart”, which has been used successfully to model day to day heat up and cool downs for “weather forecasting” since publication of his paper, “On the IR Heat Balance of the Atmosphere”, (Harvard Met. Series, 1942)
Dr. Glickstein: I hope you are retired, and have the time to examine these matters in depth. I, alas, still have to work for a living.
Max 🙂
As soon as you put in convection, which completely dominates IR radiation in the troposphere, then I’ll be interested. Until then, it’s just a matter of “Given these conclusions what assumptions can a draw?” followed by “Assume there is no convection”…