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Climate Hustle

The greenhouse effect and the 2nd law of thermodynamics

What the science says...

Select a level... Basic Intermediate

The 2nd law of thermodynamics is consistent with the greenhouse effect which is directly observed.

Climate Myth...

2nd law of thermodynamics contradicts greenhouse theory
 

"The atmospheric greenhouse effect, an idea that many authors trace back to the traditional works of Fourier 1824, Tyndall 1861, and Arrhenius 1896, and which is still supported in global climatology, essentially describes a fictitious mechanism, in which a planetary atmosphere acts as a heat pump driven by an environment that is radiatively interacting with but radiatively equilibrated to the atmospheric system. According to the second law of thermodynamics such a planetary machine can never exist." (Gerhard Gerlich)

 

Skeptics sometimes claim that the explanation for global warming contradicts the second law of thermodynamics. But does it? To answer that, first, we need to know how global warming works. Then, we need to know what the second law of thermodynamics is, and how it applies to global warming. Global warming, in a nutshell, works like this:

The sun warms the Earth. The Earth and its atmosphere radiate heat away into space. They radiate most of the heat that is received from the sun, so the average temperature of the Earth stays more or less constant. Greenhouse gases trap some of the escaping heat closer to the Earth's surface, making it harder for it to shed that heat, so the Earth warms up in order to radiate the heat more effectively. So the greenhouse gases make the Earth warmer - like a blanket conserving body heat - and voila, you have global warming. See What is Global Warming and the Greenhouse Effect for a more detailed explanation.

The second law of thermodynamics has been stated in many ways. For us, Rudolf Clausius said it best:

"Heat generally cannot flow spontaneously from a material at lower temperature to a material at higher temperature."

So if you put something hot next to something cold, the hot thing won't get hotter, and the cold thing won't get colder. That's so obvious that it hardly needs a scientist to say it, we know this from our daily lives. If you put an ice-cube into your drink, the drink doesn't boil!

The skeptic tells us that, because the air, including the greenhouse gasses, is cooler than the surface of the Earth, it cannot warm the Earth. If it did, they say, that means heat would have to flow from cold to hot, in apparent violation of the second law of thermodynamics.

So have climate scientists made an elementary mistake? Of course not! The skeptic is ignoring the fact that the Earth is being warmed by the sun, which makes all the difference.

To see why, consider that blanket that keeps you warm. If your skin feels cold, wrapping yourself in a blanket can make you warmer. Why? Because your body is generating heat, and that heat is escaping from your body into the environment. When you wrap yourself in a blanket, the loss of heat is reduced, some is retained at the surface of your body, and you warm up. You get warmer because the heat that your body is generating cannot escape as fast as before.

If you put the blanket on a tailors dummy, which does not generate heat, it will have no effect. The dummy will not spontaneously get warmer. That's obvious too!

Is using a blanket an accurate model for global warming by greenhouse gases? Certainly there are differences in how the heat is created and lost, and our body can produce varying amounts of heat, unlike the near-constant heat we receive from the sun. But as far as the second law of thermodynamics goes, where we are only talking about the flow of heat, the comparison is good. The second law says nothing about how the heat is produced, only about how it flows between things.

To summarise: Heat from the sun warms the Earth, as heat from your body keeps you warm. The Earth loses heat to space, and your body loses heat to the environment. Greenhouse gases slow down the rate of heat-loss from the surface of the Earth, like a blanket that slows down the rate at which your body loses heat. The result is the same in both cases, the surface of the Earth, or of your body, gets warmer.

So global warming does not violate the second law of thermodynamics. And if someone tells you otherwise, just remember that you're a warm human being, and certainly nobody's dummy.

Basic rebuttal written by Tony Wildish


Update July 2015:

Here is the relevant lecture-video from Denial101x - Making Sense of Climate Science Denial

Last updated on 5 July 2015 by skeptickev. View Archives

Printable Version  |  Offline PDF Version  |  Link to this page

Related Arguments

Further reading

  • Most textbooks on climate or atmospheric physics describe the greenhouse effect, and you can easily find these in a university library. Some examples include:
  • The Greenhouse Effect, part of a module on "Cycles of the Earth and Atmosphere" provided for teachers by the University Corporation for Atmospheric Research (UCAR).
  • What is the greenhouse effect?, part of a FAQ provided by the European Environment Agency.

References

Comments

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Comments 101 to 150 out of 1493:

  1. Phil, what is to explain there? The picture clearly shows a heat source (human body) emitting less heat where it is isolated. Unless you consider the earth to be it's own source of heat it has nothing to do with what needs discussed here.
  2. h-j-m, how do you explain the clothes staying cool when there is a warm body underneath them?
  3. Tom Dayton, because the clothes constitute the isolation I mentioned!
  4. Anyone who still doubts that CO2 absorbs infrared radiation should see this demo. A picture ... worth a thousand words. A video ... must be a thousand pictures!
  5. Re #104 muoncounter you wrote:-

    "Anyone who still doubts that CO2 absorbs infrared radiation should see this demo..."

    True, I don't know anybody who thinks CO2 doesn't absorb IR radiation. But there is a large number of people who believe they exist; rather like bad fairies, somewhere out there, trying to prove there is no greenhouse effect.

    I also know a lot of people who doubt CO2 doesn't emit infrared in exact proportion to the amount it absorbs... Now let us all think hard where these really strange people are to be found!
  6. Re #98 muoncounter you wrote:-
    "However, we know that both objects radiate, albeit at different wavelengths. Some of the cooler object's radiation is absorbed by the warmer; however, more total energy is transferred from warmer to colder."

    Which is fair enough, it is what your MIT link explains. And then for some bizarre reason you appear to make an exception for GHE radiative transfer :-

    "The 2nd Law is satisfied AND the greenhouse effect still works." (my emphasis)

    But the GHE requires that GH gases increase the temperature of the surface that is already hotter than the upper troposphere. (The troposphere can only get warmer than the surface in the exceptional condition of temperature inversion.)

    To get the surface temperature to increase the GH gases would have to cause, as you put it, 'a net transfer of total energy' from the troposphere to the surface.

    You also cite this post:-

    #83 CBD Your belief that this means energy can ONLY flow from 'hot' to 'cold' is simply nonsense, and rejected as such by all but the outermost looney fringe of modern physics.

    with favour. Surely you notice this post is in complete conflict with your MIT link?
  7. We often hear people say that GHG warms the surface. I understand its use in common language, but it's not to be taken litterally. Indeed they don't, they only reduce the outgoing flux. It's the unbalanced flux from the sun that makes the surface warmer.
  8. Re #107 Riccardo you write:-

    "I understand its use in common language, but it's not to be taken litterally."

    I do hope you don't mean this. Either the GHGs cause a warming of the surface or they don't. I have yet to read anything on the GH effect that doesn't posit an actual (literal?) warming of the surface.

    Since they are found in the atmosphere CO2 and H2O in the atmosphere actually are big players in radiating heat from Earth, you can see how much by looking at IR images of Earth here

    But the Earth wouldn't bake if there weren't any GHGs in the atmosphere. The average temperature would not be different, only the distribution of temperature would change, given the lack of heat transport from equator to poles by oceans and atmosphere.
  9. darmobel
    I meant exactly that. It should not come as surprise, often physics and common language share words with slightly different meaning.
    GHGs cause a change in the balance of the energy fluxes, but do not directly heat the surface. (Note the difference between energy and heat). It would be more correct to say that the greenhouse effect impedes cooling.
  10. h-j-m @101
    So areas of the human body that are surrounded by clothes and hair emit less heat than those exposed ? Is that what you're saying ? I'm affraid thats not true. The part of the body under the clothes is emitting just as much heat as the exposed areas (the face, for example). But the clothes are clearly emitting less heat. Whats happened to the rest ?
  11. Re #109 Riccardo, you do not respond about the effect on the Earth's average temperature of removing all the GHGs from the atmosphere, will it go up or down?
  12. Phil, I just answered to your question which was about what a picture showed. The picture itself can only show an image of the radiation that arrived at the camera. Sorry, I thought that to be obvious. To deduce from a picture what it does not show is pure speculation. I try to avoid entering that realm.
  13. damorbel @108

    You need to understand the difference between
    GHGs warms the surface and
    GHGs cause a warming of the surface
    These statments are different. My analogy with clothes may help you. Clothes do not warm your body, but they do cause your body to warm.
  14. h-j-m @112

    If you refer to my post @98 I suggested you explain the temperature distribution, I did not suggest that you describe it. If you do not wish to try, then thats up to you, but doing so should help you with the errors you are making in your comments.
  15. Phil, I am referring to your posts #98 and #110. In your post #110 you state: "The part of the body under the clothes is emitting just as much heat as the exposed areas" and ask me to comment on this. Unfortunately you fail to provide any evidence to back that assumption. To explain something on the base of pure assumptions is called speculation in contrast to science where explanations are based on facts.
  16. #105: "a lot of people who doubt CO2 doesn't emit infrared in exact proportion to the amount it absorbs"

    You accept that CO2 absorbs IR, but now posit that it re-emits in 'exact proportion'? If that were true, why does the IR emitted by candle flame disappear when the CO2 is absorbing its IR? If emission were in 'exact proportion' to absorption, where is that emitted IR in the demo? Or does the IR absorbed remain as kinetic energy in the gas, resulting in increased temperature? -- A result completely consistent with all the other grade school level science experiments showing that a bottle with CO2 attains a higher steady state temperature than a bottle of room air.

    "But the GHE requires that GH gases increase the temperature of the surface"

    No, the GHE increases the temperature of the atmosphere. Your parsing of words and inserting phrases that aren't in the question is quite tedious; it isn't contributing to the actual debate -- which is, I suspect, your actual purpose in hijacking this thread.

    "Surely you notice this post (CBD's #83) is in complete conflict with your MIT link?"

    In what way? Be specific, without drifting into irrelevancies. This isn't a course in rhetoric.

    #108: "CO2 and H2O in the atmosphere actually are big players in radiating heat from Earth ... the Earth wouldn't bake if there weren't any GHGs in the atmosphere. The average temperature would not be different" Please substantiate these new claims with something more than a weather satellite image -- which doesn't illustrate whatever your point is.
  17. Re #113 Phil You wrote :-

    "Clothes do not warm your body, but they do cause your body to warm."

    Um... not true. While you are alive it is your (fuel burning) metabolism that keeps you warm, your clothing is an insulator that reduces the rate of heat transfer to the ambient, should the ambient be below 37C.

    If the ambient is above above 37C then you have problems because you cannot switch your metabolism off (well you can, but the problem is to switch it back on again) and, in the absence of any action to change the situation your body temperature may well rise to heatstroke levels.

    If you cannot switch your metabolism back on, your body will slowly settle to ambient temperature, what ever that happens to be.

    How long it takes to reach ambient depends on how good an insulator your clothes are. If you are put in a large vacuum flask with mirrored walls to reduce the radiative heat transfer then it might take days; without the mirrored walls - a day?

    The point is the insulator, be it a woolly blanket, a multilayer mylar sheet or a vacuum container, can only slow down the rate of heat transfer and thus the time taken to reach ambient. Your clothes keep you warm because you are continually replacing the lost heat with your metabolic heat - until you die, of course!
  18. Re #116 muoncounter You wrote :-

    "why does the IR emitted by candle flame disappear when the CO2 is absorbing its IR?" Because the IR from the candle is from a small, high temperature source and the CO2, absorbing the IR, warms only a little because there is much more of it.

    Given time and a sufficiently sensitive set up, the warming of the CO2 would be detectable - because the CO2 also emits IR and this would show up on an IR imager.

    A suitably sensitive IR imager may be able to resolve 1/1000K, such devices detect bodies under piles of concrete rubble when looking for earthquake victims.

    You wrote :-

    "No, the GHE increases the temperature of the atmosphere."

    When ever I have read about the GH effect it has been the surface temperature that was the worry. Sorry if I picked you up wrong!

    You wrote :-

    " "Surely you notice this post (CBD's #83) is in complete conflict with your MIT link?"
    In what way? Be specific, without drifting into irrelevancies."

    In #83 CBDunkerson wrote :-

    "energy flows into all surrounding objects regardless of their relative temperatures."

    Whereas the MIT link (section 2) has this :-

    "No process is possible whose sole result is the transfer of heat from a cooler to a hotter body"

    Now the reason 'sole result' is included is because heat pumps and refrigerators do transfer heat from a low temperature to a high one but they require another source of energy over and above the 'energy' they are pumping, thus the energy transfer the bring about is not the 'sole result' or sole action if you will.

    Thus CBDunkerson's statement contradicts your MIT link.
  19. damorbel,

    Solar energy arrives primary in the frequencies of visible & UV light. This passes through CO2 unimpeded. The planet absorbs the energy and re-emits it largely in the IR range (i.e. heat). CO2 and other GHG gases slow down the emission of these frequencies to outer space. This causes a increase of energy at the planet surface, and a cooling of the stratosphere since the rate of energy loss has slowed, until a new equilibrium is reached.
  20. #118: "Given time and a sufficiently sensitive set up, the warming of the CO2 would be detectable"

    Then your 'exact proportion' argument from #105 requires a very low constant of proportionality. And you accept that the gas is warmed -- please explain where this excess kinetic energy goes if the proportion emitted is so low.

    "I have read about the GH effect it has been the surface temperature that was the worry."

    Please tell us what you've been reading and what surfaces you appear to be worried about.

    "the reason 'sole result' is included is because heat pumps and refrigerators do transfer heat"

    Yes, I am sure Clausius had exactly refrigerators and heat pumps in mind.

    Perhaps you ought to state for the record: Do you accept the idea that greenhouse gases absorb infrared energy radiated from the surface of the earth and oceans, resulting in a warming of the atmosphere? Does CO2 play a major role in this process? If not, what are your specific objections? What published science (as opposed to vague references to individual interpretations of the 2nd Law) can you cite to support your objections?
  21. damorbel, you wrote: "If the ambient is above above 37C then you have problems because you cannot switch your metabolism off (well you can, but the problem is to switch it back on again) and, in the absence of any action to change the situation your body temperature may well rise to heatstroke levels."

    Of cause that is true in principle. But to my knowledge other actions take place as the body will shed water to increase the heat transport and in consequence the dehydration will lead faster to terminal conditions then the rising temperature.

    Anyway, I think this will be my last post here, The kind of reasoning here seems to give me headaches. I just happen to live in one world of which I assume it exists and is real. I have to confess that assuming an other world to exist and being real as well seems already too much for me. Switching between this two worlds seemingly according to which one fits the argument better makes it even worse.

    Let me jut explain these two worlds which I will just name here and there.

    Here matter absorbs radiation only at certain frequencies and is either transparent or reflects or scatters the rest due to its chemical composition. Here matter emits radiation at certain frequencies (producing something called colour at the visible range) again due to its chemical composition. Here I can feel the warmth of direct sunlight though that should be dwarfed by the earth's surface radiation not to mention back-radiation. Here temperature differences cause winds to blow, currents to flow, water to evaporate and in essence everything needed to sustain life or even to allow for its development.

    There all matter absorbs all incoming radiation which means that it acts effectively as a black-body. Consequently it also emits radiation where the according black-body spectrum, which only depends on the temperature of the black-body, determinates wavelength range and intensities. There temperature differences are the result of imbalanced energy flows which are caused by black-bodies emitting energy depending on the temperature of the black-body which again is caused by imbalanced energy flows etc. etc. ad infinitum.
    There is a world not only hard to understand but even harder to accept as real.
  22. h-j-m:

    Given:

    (1) that the atmospheric greenhouse effect is well-documented, empirically, as discussed on this website, other websites, and in the peer-reviewed literature; and

    (2) that the consequences of enhancing this greenhouse effect via anthropogenic emissions of greenhouse gasses - that is to say, global warming - also has a plentitude of empirical evidence to support it, as described on this website, other websites, and in the peer-reviewed literature;

    It would seem to me that there is not much question as to which of the below alternatives is more likely:
    - that all this empirical evidence (global cryosphere mass balance decline, sea level rise, changing migration patterns, pest prevalence in increasingly higher latitudes, temperature anomalies, &c &c &c) isn't really pointing to global warming via the atmospheric greenhouse effect
    - that you and damorbel have managed to misunderstand thermodynamics
  23. Re #121 h-j-m wrote:-

    "But to my knowledge other actions take place "

    A feature of this kind of discussion is the tendency not to see the bigger picture. My vision of man sized vacuum flasks was rather far fetched and any working version would probably stop any of your "other actions" so effectively that the death of the person inside would not be long delayed, thus illustrating the bodies return to equilibrium with the ambient temperature!

    I enjoy your contributions, you can express yourself on thermodynamics without difficulty. The trouble is few of your readers are able to appreciate what you are saying.

    For my part I try to explain, if I am not understood I try to work out why, because I would like to better explain these matters, especially for non experts. This is a serious ambition because there is a limited future in just talking to experts.

    There are plenty who will never accept that the AGW hypothesis does not hold together but others, who are genuinely interested, need to be supported by well crafted explanations, that is what I am trying to do here!
  24. Re #122 Composer99 wrote:-

    "the atmospheric greenhouse effect is well-documented, empirically "

    This thread is about inconsistencies in the well documented explanations of the greenhouse effect.
    Response: [Daniel Bailey] Just to be clear, you mean supposed "inconsistencies", with you being the supposer.
  25. Re #120 muoncounter, you wrote:-

    "Yes, I am sure Clausius had exactly refrigerators and heat pumps in mind."

    Clausius was not an ignoramus, he was almost certainly aware of refrigerators since a patent for a refrigerator was granted to Jacob Perkins in 1834, when Clausius was 12.

    you wrote:-
    "Do you accept the idea that greenhouse gases absorb infrared energy radiated from the surface of the earth and oceans, resulting in a warming of the atmosphere?"

    Perhaps 20% of atmospheric energy gets there by radiative transfer, of which CO2 accounts for perhaps 7%, another 20% by convection from the warm surface and 60% is due to water evaporating.

    In contrast about 80% leaves the Earth by radiation from atmospheric gases, of which 25% is due to CO2 and the remaining 20% by direct radiation from the surface. OK?

    Most of these figure come from the well known diagram of of K Trenberth, (I am having difficulty with the link - here's hoping!) they are the credible part of his diagram. The 'back radiation' idea is misconceived and certainly does not change the temperature distribution.

    Since the presence of H2O and CO2 etc. whose weak effects cannot distort the heat distribution, a distribution which is determined by much more powerful gravitational and cosine effects, exactly how the how the Sun's energy is absorbed is not of the first relevance.

    It is curious to note that Svensmark's cloud hypothesis has far greater traction than the GHG one.

    The death knell of the GHG hypothesis really is the effect of gravity on the atmosphere. The troposphere has a vertical temperature gradient which is a uniform 6.5K/km from the equator to the poles. This corresponds to the change of gravitational potential energy with height, it leaves no room for any radiative GH effect; it can even account for the rather strange temperature profile of the Stratosphere.
  26. I believe the substance of my criticism of your position is in a later part of my comment #122, namely:


    It would seem to me that there is not much question as to which of the below alternatives is more likely:
    - that all this empirical evidence (global cryosphere mass balance decline, sea level rise, changing migration patterns, pest prevalence in increasingly higher latitudes, temperature anomalies, &c &c &c) isn't really pointing to global warming via the atmospheric greenhouse effect
    - that you and damorbel have managed to misunderstand thermodynamics


    [Emphasis in underlines mine in this comment, not in #122.]

    That is, the inconsistencies are more the purview of skeptics/contrarians attempting to appeal to thermodynamics than of the scientific evidence supporting the existence of the greenhouse effect.

    When reviewing this thread, as a non-scientist (I am a musician by training) I have found the posts of the likes of muoncounter, Phil, et al to be clearer and more compelling than the posts of yourself or h-j-m.

    In particular, your blanket analogy in #117 practically mirrors the analogy used in the original post, save that you draw what appears to be a bizarre conclusion from it.
  27. "Let me jut explain these two worlds which I will just name here and there."

    h-j-m - what is really going on, is that you have misunderstood physics and created an invalid worldview which means you would incorrectly predict the outcome of experiments. The best approach is learn what it really correct and how they are reconciled (sit down with a text book). Making real world decisions (like voting on measures to deal with climate change) on the basis of an incorrect understanding is a bad thing.
  28. Re #126 Composer99, you wrote:-

    "your blanket analogy in #117 "

    Composer99, it isn't an analogy. A blanket is one sort of insulator. Anything that interferes with heat transfer can be an insulator of greater or lesser effectiveness.

    Your doubts about my competence in thermodynamics would be so much more admirable if you knew about insulation.
  29. "Anything that interferes with heat transfer can be an insulator of greater or lesser effectiveness."
    Indeed.
  30. Damorbel @128,

    "Your doubts about my competence in thermodynamics"

    Actually, your failure to grasp a scientific theory (not hypothesis) that has been around for over 150 years seriously questions your competence in thermodynamics.

    Have you actually read Roy Spencer's posts on this matter which I and others have directed you to?

    Talking of Spencer, have you read Spencer Weart's book, The Discovery of Global Warming? I'm thinking not. But then again, why would you-- you clearly believe that you know better than Arrhenius, Fourier, Tyndall and many, many other eminent scientists who get it. Maybe you are a D-K victim after all.

    Given that you cannot wrap your head around this fundamental theory underlying physics of AGW, I hope not to see you arguing points on any other page. Why argue other points related to climate science and AGW if you cannot grasp the greenhouse effect?

    We get it, you think AGW is not real, and your behavior here has demonstrated that no one is going to be able to convince you otherwise, so please (pretty please) stop wasting everyone's time.
  31. Composer99, as I picked on the matter of insulation (blanket analogy) first (starting with post #15) I feel obliged to reply to your take on it.

    You wrote (post # 126) "In particular, your blanket analogy in #117 practically mirrors the analogy used in the original post, save that you draw what appears to be a bizarre conclusion from it." which was in reply to a posting by damorbel. As I share his opinion in this matter let me try to make things more clear.

    Our conclusion is simple, however effective any insulation is, it can not cause the isolated body to warm unless there is a source of heat inside the insulation. Does this contradict what is said in the lead article? Let's see.

    It states: "If you put the blanket on a tailors dummy, which does not generate heat, it will have no effect. The dummy will not spontaneously get warmer. That's obvious too!"

    I fail to spot any contradiction, do you?
  32. h-j-m,

    Your conclusion is indeed simple, and wrong.

    The solar energy is the heat source. It passes through the atmosphere in one form (visible & ultraviolet light), get absorbed by the planet and re-emitted in another form (infrared light) that the greenhouse gases in the atmosphere insulate against.
  33. Our conclusion is simple, however effective any insulation is, it can not cause the isolated body to warm unless there is a source of heat inside the insulation.

    There is no claim that the Greenhouse Effect warms the Earth, only that it slows the Earths emission of heat into space, this was explained to you by Riccardo @107, but you seem to have ignored this. In this sense the GHE does behave exactly like clothes or a blanket around a human body. The human body gets its energy through metabolising food, circumnavigating the insulation. The Earth gets its energy from the sun, also circumnavigating the GHE insulation because the frequencies of EM radiation from the sun do not match the emitted ones from Earth which do, sadly, lie in the CO2 absorption bands.
  34. Re: damorbel (125)
    "Clausius was not an ignoramus, he was almost certainly aware of refrigerators since a patent for a refrigerator was granted to Jacob Perkins in 1834, when Clausius was 12."
    Hey, that Clausius guy traveled in rarified circles: hobnobbing with Perkins (who lived in England) while Clausius was growing up in Germany. Or did he read about it in Europe Today?

    Fascinating, the stuff I learn here...

    The Yooper
  35. Re #130 Albatross I have have a copy or have read most of the books, articles etc. etc. you refer to, I possess many more.

    You may have noticed that I have confined my arguments to the subject of this thread which effectively claims that GHGs in the upper troposphere can induce about 33K temperature rise above the 255K said by climatologists to be the equilibrium temperature of Earth without GHGs. This is the position of the IPCC, it is in all their assessment reports which are search-able as PDF files on my computer.

    What is not identified in the IPCC reports is the temperature of the upper troposphere, it is very cold about -50C at 50km altitude, about -20C at 4km.

    There is no way the CO2, H2O vapour and whatever other GHGs you find 'up there' will raise the temperature at 0km by anywhere from 23C to 33C.

    What happens is the GHGs (at -20 to -50C) absorb some of the radiation from the warmer surface (-10C to 25C) on average and a small amount of heat is added to the atmosphere in addition to the vast amount transferred by the evaporation/rainfall heat transfer cycle.

    All of the heat in the atmosphere is radiated to deep space by the GHGs.

    Some of the heat in the Earth does not get into the atmosphere because it is radiated directly to deep space.

    Because heat transfer can only go from a hot place to a cold one, no heat at all can be transferred from the troposphere to the surface because the troposphere is always colder than the surface and, since no heat can be transferred in this direction, there can be no warming effect; it would be like getting a ball to roll up hill completely unaided.

    The reason the air at altitude is colder than at the surface is fairly simple. Think of a ball thrown vertically, gravity reduces its velocity, this means its kinetic energy =1/2mv^2(KE) is reduced.

    There is no real difference between the thrown ball and an air molecule except the temperature of a gas is proportional to the KE of its molecules, so in the troposphere the temperature of the air drops linearly with height at 6,5C/km because the KE is transformed into potential energy (PE) = mass x gravity x height (mgh). PE is seen to increase linearly with height which means that the KE/Temperature decreases linearly with height (as observed).
  36. Re #134 Daniel Bailey, you wrote:-

    "Clausius guy traveled in rarified circles"

    Just like Bill, he just wouldn't come home.
  37. Agreed CO2 intercepts some of the LWIR from the Earth, but it can only re-radiate just less than 1/2 back to the Earth which, for most of the time is warmer and therefore cannot make use of, or be affected by those low-energy photons.The effect of this gas,at 0.028% of the atmosphere is negligible. Water vapour is the greenhouse gas, except that it doesn't work like a greenhouse. The Earth is the watery planet and its climate can be fully accounted for by the density of the atmosphere and H20 and its three states. C02, were it not an essential component of life which is a special feature of the Blue Planet, could be ignored.I want my children and my children's children to have the same lifestyle as I've had.Sure there may or may not be peak oil. So what. If as many dollars had been put into battery research as have been squandered in this climate stuff, we might have been that bit further down the road to the hydrocarbonless society.
  38. RE# 137 AWoL

    The effect of this gas,at 0.028% of the atmosphere is negligible.

    Please offer a citation in peer reviewed literature that claims this is the case.

    For if it is you would need to explain to the reader how Satellite measurements of outgoing longwave radiation are incorrect.
  39. Damorbel,

    "What is not identified in the IPCC reports is the temperature of the upper troposphere, it is very cold about -50C at 50km altitude, about -20C at 4km."

    I'm not going to argue with you. Maybe it was a typo or maybe it was a very revealing slip-- but the troposphere doesn't extend to 50 km. The mid troposphere is typically deemed to be around 500 mb or around 5.5 km where temps. are typically near -20 C. Temperatures are -55 C or so between 11 km and 20 km. At 50 km you are in the stratopause where temps are a balmy -5 C or so. Surely you read that in the many books that you claim to have read.

    Maybe the wise rabbet can explain all this to you.
  40. Bibliovermis and Phil, Are you really saying that incoming radiation from the sun is not effected by greenhouse gases?

    Want to bet?
  41. All,

    Here is an online MODTRAN applet maintained by Dr. Archer. Have fun.
  42. #125: "The death knell of the GHG hypothesis really is the effect of gravity on the atmosphere."

    Had you disclosed that you were a devotee of that idea sooner, this wouldn't have gone on this long. Rabbett took it down back in May. Are you a student of Jelbring? If so, why didn't you say so -- at least that was a published reference.

    "Svensmark's cloud hypothesis has far greater traction"

    Another idea shot down in flames.

    #135: "no real difference between the thrown ball and an air molecule"

    Ah, the heat at the surface is due to all that liberated gravitational potential energy, just like a ball that fell to the ground... Except the air molecules in question have not fallen from the top of the atmosphere. Or did you mean that since PV=nRT, the higher surface pressure results in higher temperature? Someone kicked that around here not that long ago, but I don't have the thread handy.

    So we must choose: Perhaps Clausius knew of a patent issued for an evaporative refrigerator (which depended on reducing the 'caloric' content of fluids -- it's online) and was thus motivated to include the words 'sole result' in thermodynamic theory. And Damorbel is the only one who knows this... but that renders the 2nd Law of Thermodynamics kind of trivial. Or perhaps 'sole result' refers to net energy transfer, elevating the work of Clausius to that of the key discoveries of science. Just like the words net force occupy the central place in Newton's 2nd Law, elevating that to the level of Law.

    #123: "I try to explain, if I am not understood I try to work out why" Here's a suggestion: Try to listen to what other people are saying and digest what they are asking. Then avoid repeating the same explanation without offering any substantiation.
  43. Re #139 Albatross Yes a typo, -50C at 10km, more strength to my argument, it puts -60C to -80C between the the bottom and top of the troposphere, where then is this GHG warming effect coming from?

    Your link to Rabbet is very informative, of high altitude GHG emissions (CO2 etc), he says:-

    "Below that level, energy emitted by a greenhouse gas molecule is soon absorbed by another relatively nearby one. Thus the energy simply cannot be radiated to space to balance the incoming solar energy."

    which satisfies all observations of molecular absorption and emission. But don't you notice that this kills off the 'back radiation' nonsense? There are plenty of gases, the so-called greenhouse gases, that emit and absorb radiation; Rabbet is acknowledging that adjacent GHG molecules will absorb GHG emitted photons.

    To a non-climatologist this means that the thermal equilibrium of a gas is not disturbed by the phenomenon of molecular emission/absorption; a climatologist does not notice the absorption part of the phenomenon and claims that the emitted photons are not absorbed in the atmosphere but somehow, contrary to the 2nd law of thermodynamics, bunch together to form a radiative flux downwards to Earth's surface.

    Thank you for the link. This phenomenon was explained by Einstein in his 1917 paper on emission and absorption, Rabbet is the first person I have come across who recognises this reality in popular literature.

    Re #142 muoncounter, you also link to Rabbet and further to Jelbring on how heat is distributed in a gravitationally retained atmosphere.

    In your link to Rabbet you will find a further link to Steve Goddard's thread on the matter of atmospheres, gravitation and temperatures, there are currently over 400 postings and they make interesting reading. Given the vigorous discussion, your claim that "Rabbett took it down" is just absurd.

    Would you care to say what Rabbet wrote that convinced you? I am not interested who writes something, I need to know the argument used. Please tell me which part of Rabbet's post convinced you, I would like to check it out.

    The same with Jelbring.
  44. @damorbel: " a climatologist does not notice the absorption part of the phenomenon and claims that the emitted photons are not absorbed in the atmosphere but somehow, contrary to the 2nd law of thermodynamics, bunch together to form a radiative flux downwards to Earth's surface."

    ...except that's not *at all* what climatologists claim. To say they do is either to misunderstand the science, or to disingenuously misrepresent what climatologists believe.

    The point is not that all of the absorbed photons will go back down. The photon re-emission by GHG molecules happens in a random direction.

    The point, however, is that without this absorbtion/emission cycle, the heat would go directly into space. Now, it stays in the atmosphere longer, and some of it does make its way back to the surface. This is why temperatures have been going up, and it in no way violates the 2nd law of thermodynamics.

    It would be nice if you stopped repeating false information. Please consider it.
  45. @AWoL: "The effect of this gas,at 0.028% of the atmosphere is negligible."

    No, it isn't. See CO2 effect is weak and CO2 is not the only driver of climate.

    "I want my children and my children's children to have the same lifestyle as I've had."

    They won't if we don't take care of AGW. In fact, their lifestyle will positively suck.

    You seem to believe there's no money to be made in developing renewable energy and other green technolgies. Perhaps you should tell that to China, they're taking the leadership in these areas while the propaganda spread by Big Oil is causing the US miss the boat on these opportunities. Think about it.
  46. #143: "the so-called greenhouse gases, that emit and absorb radiation; Rabbet is acknowledging that adjacent GHG molecules will absorb GHG emitted photons."

    Your logic continues to spiral downwards. GHG molecules absorbing photons increases the temperature of the atmosphere -- and hence, warming.

    "and further to Jelbring" I have no particular interest in Jelbring; I assumed that was the source of your gravity=temperature gradient. If not Jelbring, perhaps you are a follower of Landscheidt, then?

    "you will find a further link to Steve Goddard's thread ... over 400 postings ... the vigorous discussion ... is just absurd."

    Any credibility you've tried so valiantly to establish here, now gone poof. As far as the number of postings on one of $G's threads being an indicator of substance, value or thought: Really?

    Here is what Dr. Roy Spencer posted on a similar thread in Watt$land:

    But it’s when that volume is exposed to outside influences — like IR radiation from the solar-heated surface of the Earth passing through that volume — that a temperature change can occur as a result of adding more CO2 to the volume. -- emphasis added

    Absurd is as absurd does.
  47. h-j-m:

    Rather than cryptic wager challenges, why not share a link or other citation to peer-reviewed literature showing the magnitude of greenhouse gas effects on incoming solar EM radiation?
  48. As several posters here accuse me of misunderstanding, misinterpret and general lack sufficient knowledge of physics and thermodynamics I will gladly admit all of that. Nevertheless, as posters doing so fail to provide any evidence in the end it just constitutes an ad hominem comment. Being aware of my poor knowledge I check facts before writing, double-check them while writing and triple-check them before posting.

    Now I will try to do it an other way.

    Is it true that matter absorbing incoming energy will result in either
    1.a phase change (solid to liquid, liquid to gas, gas to plasma) and/or
    2. taking up more volume and/or
    3. emitting radiation?

    If we observe gases absorbing incoming energy at surface temperatures, is it true we will observe them gaining volume and emitting radiation (getting hotter)?

    If you answered no to at least one of the questions please tell my why, if not then please tell me what specifically makes green house gases so special.
  49. Composer99, for the simple reason that I have already done that in post #23. You can also cross-check with the link DSL provided in post #27.
  50. h-j-m:

    You mean the Wikipedia graph?

    That appears to be taken into account by the graph provided by others (from Science of Doom) several comments down: DSL/Ned (comments #26/27).

    I'm not sure I follow. Surely, if greenhouse gasses in the atmosphere can alter the flow of radiation coming in from the Sun, if that radiation is at the correct wavelenghts, then they can affect radiation coming up from the surface of the Earth, particularly since a very large part of that radiation occurs in the wavelengths most vulnerable to greenhouse gas effects.

    Leaving out the constant heating from the Sun, the net flow of heat energy, per the Second Law of Thermodynamics, should be from the Earth, through the atmosphere, into space. That is what we see. Greenhouse gasses in the atmosphere delay this flow of heat energy and (bringing incoming Solar radiation back into the picture) force the Earth to increase its surface temperature to bring it back into radiative equilibrium. Again, we see this in empirical observations.

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