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The 2nd law of thermodynamics and the greenhouse effect

Posted on 22 October 2010 by TonyWildish

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.

This post is the Basic Version (written by Tony Wildish) of the skeptic argument "The 2nd law of thermodynamics contradicts greenhouse theory".

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Comments 151 to 200 out of 260:

  1. Replying to Ned, post number323 (I like your step by step approach.Much appreciated) For me everything is fine until we get to step C and D and it's substeps D2, D3, D4. (C) "Greenhouse gases in the atmosphere will reduce the flux of outgoing longwave radiation within their absorption bands." True, bearing in mind that only 1 in 2,500 molecules is involved and only a tiny part of the IR outgoing spectrum is involved.Is this a significant effect in comparison to much more obvious transfers of heat, such as conduction/convection from the surface and the very obvious role of water vapour in heat transfer? My instinct says no. D)"The reduction in OLR cause the temp of the planet to rise." Logically yes , but only if the proportion of IR intercepted by CO2 is high. I think it is low...very low, so low that it cannot be directly measured. So to that I would say that any theoretical rise in temperature will be so small as to be immeasurable. E)"As the temperature rises, more OLR is emitted outside the greenhouse gas absorption bands." Let's accept a small temperature rise, for the sake of argument. All that happens then is that a greater fraction of OLR by passes CO2,zooms out into space and reduces further what little significant effect(if any) CO2 had on planetary warming. F) Agreed ,as F follows from E (D.2) "Some of this radiation goes outward to space, and is lost to the planet's system. Some of it goes inward towards the surface." Yes a lot, more than 1/2, goes out to space,consequently less than 1/2 returns earthwards but produces no effect as the frequency is too low to raise the temperature of molecules in a higher state of excitation. (D.3) "This downwelling longwave radiation from the atmosphere is absorbed by the planet's surface." Problems here. It may be absorbed,if it gets there. But most of the time the surface will be hotter and nothing will happen. Or if it is cooler, most of the time a blanket of fog/mist will form. The only place where it might have an effect is in dry cold deserts.....but that, at any one time, will be but a tiny proportion of the earth's surface. So, once again theoretically possible, but in practice, relatively seldom will the requisite conditions be met for any significant heat transfer to take place from atmosphere to the surface.I can't help but feel that the height of the troposphere is one of the principal regulators of the earth's temperature. High troposphere.... lot of heat loss(Tropics). Low troposphere..... low heat loss(high latitudes). What I'm saying is that there is a high degree of autoregulation/homeostasis built in to our atmosphere and water and water vapour are the big players.The atmosphere's principal function is to provide a conduit for water vapour and water(clouds).The difference between us is that you say there is a significant heat transfer involving CO2, while I say that while it is theoretically possible that CO2 might raise the temperature of the atmosphere, the very low density and the minor quantity of energy involved, in comparison to conduction/convection/evaporation/condensation, make it difficult to accept the model that you propose. And there we have to leave it, unless new evidence or a better explanation come to pass. However if nothing else, the sticking point has been identified. (D.4) "The absorption of this downwelling radiation reduces the magnitude of the net flux of longwave radiation leaving the surface, making the surface warmer than it would have been if it were not surrounded by an atmosphere that includes greenhouse gases." Couldn't that be tested experimentally? Take a hemisphere of red hot iron. Note the cool down time. Exactly the same conditions, and place a wire mesh hemisphere(radius say 2-3ft) over the heated iron hemisphere. Will it affect the rate of cooling or not? Surely the wire mesh would act or interact with the hemisphere in a similar way to that which you say happens between the Earth's surface and atmospheric CO2? Or try the same thing in a room of air and then do the same thing in a room of 100%CO2. My instinct says that in neither case will there be a measurable increase in cool-down time. The wire mesh will simply act as a relaystation of radiation outwards,and CO2perhaps functions in much the same way.According to you the downwelling radiation from the wire will reduce the netflux of longwave radiation leaving the surface....hence lengthening the cooling time. Maybe more information could be gained if there was some way of heating the wire in a controlled manner and finding out just what temperature it had to reach to produce a readily detectable difference in rate of cooling of the hemisphere.If you have to add a considerable amount of energy then my interpretation is correct. If the addition of little or no energy still slows the rate of cooling appreciably then you are correct.If a lot of energy has to be added then you are very wrong. If none or very little then you are correct. In other words , this would not just prove that you were right or wrong ,but supply a figure as to how much you are wrong....or right.
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    Moderator Response: Regarding your response to (C): The proportion of CO2 molecules relative to other molecules is irrelevant. What matters is the number of CO2 molecules in a volume of space. Many people are confused on this point because the typical way of referring to the amount of CO2 is as PPM air molecules. But that way of referring is merely a convenience to avoid the complication that the number of air molecules differs across parts of the atmosphere. If you want to continue to discuss that, probably the thread "Human CO2 is a tiny % of CO2 emissions" is more relevant than this thread.

    Regarding your belief that the effect of CO2's interception of "outgoing" IR is not significant "in comparison to" conduction and convection, again you need to realize that its relative effect is not relevant; what matters is the absolute size of the effect. Secondly and more importantly, "outgoing" means "on the way to space," and what counts is whether that energy makes it all the way to space. Convection and conduction do not change the amount of energy that goes out of the Earth's whole system (land + water + air). They do not intercept energy on its way out, because they do not operate on radiation, which is the only way energy can escape the whole system.

    Regarding your response to (D), you are incorrect that the proportion of IR intercepted by CO2 is so low that it "cannot be directly measured." Actual empirical measurements can be seen in, just for example, the post "CO2 effect is weak." Also note that the "proportion of IR does not matter; what matters is the absolute amount of energy intercepted, which does map to absolute amount of IR. You might also want to read "CO2 is not increasing" and "CO2 effect is saturated." If you want to further discuss that, one of those threads probably is more relevant than this one.
  2. AWoL "only 1 in 2,500 molecules is involved" Check this quote from Waste heat vs greenhouse warming "Given that air molecules at surface pressure collide with other molecules 10^9 times per second, this energy is rapidly distributed to all the molecules in the air mass - N2, O2, CO2, Ar, H2O, etc. And once the GHG's in the air mass reach the higher temperature, they will radiate IR at the appropriate rate for that temperature."
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  3. Michele @ 147. Every prediction of quantum theory that could be tested by experiment thus far has proved true. Physicists have been very busy proving it's true, in other words. How does Claes Johnson theory fare? The way I see it, according to his theory, a multiple mirrors type concentrating solar plant can not work. However, they do. Perhaps I misinterpret the "energy is transferred only from warmer to cooler" bit. Does it mean energy or heat? Awol, do you have any evidence backing up your assertion that downgoing IR radiation is too small to be measurable? Did you check whether it has been measured or not?
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  4. AWoL comments @ 151:
    (C) "Greenhouse gases in the atmosphere will reduce the flux of outgoing longwave radiation within their absorption bands." [Quoted by AWoL from Ned @223).] True, bearing in mind that only 1 in 2,500 molecules is involved and only a tiny part of the IR outgoing spectrum is involved.Is this a significant effect in comparison to much more obvious transfers of heat, such as conduction/convection from the surface and the very obvious role of water vapour in heat transfer? My instinct says no. [Emphasis mine.]
    Your instinct? You surely realize that relying on instinct is a sub-optimal manner of assessing scientific data, especially in the era of quantum physics & relativity.
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  5. Composer99@154, Yes... "my instinct"=my best guess based on current experience and knowledge. If you have got precise data,rather than a best guess, then I do hope you will reveal it to all on this website which I think is the purpose of this website. Is an understanding of quantum physics and relativity necessary for understanding of climate models? If so what books would you recommend for a beginner to get up to speed?
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  6. Re #159 AWoL you wrote:- "Is an understanding of quantum physics and relativity necessary for understanding of climate models?" Indeed it is. Quantum physics arose because there was no satifactory explanation for radiative transfer of energy that could be derived from classical mechanics. Classical mechanics (kinetic theory) was OK for heat in atoms and molecules but it simply didn't work for radiation, even with Maxwell's electromagnetic equations. It was Max Planck (On the Law of Distribution of Energy in the Normal Spectrum - 1901) who, basing his work on Gustav Kirchhoff's 'black body' paper (On the Relation Between the Emissive and Absorptive Power of Bodies for Heat and Light - 1862) who opened the door to understanding of the quantum aspects of radiation and matter. In turn Einstein (1905, 1909 and 1917) picked up the torch and the rest, as they say, is history. As for recommending books, that is rather difficult. There are translations of the original works and it is highly advisable to read them because the subject, as it is taught today, is widely misunderstood, particularly Kirchhoff. The relatioship between the Earth and the Sun in terms of energy is very simple in some ways but when you read in all climatological explanations that the Earth 'emits in the infrared like a black body', and 'the Earth's temperature is dependent on its albedo', the you must realise that 'climatology' has fallen at the first fence and you are completely lost, the only thing to do is to turn round and go back to the beginning.
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  7. Phillipe Chantreau @153 Perhaps you misread that which I wrote? Which was " so low that it cannot be measured." (my reply to statement D) The "it" referred to a theoretical change in temperature of the planet and not to the quantity or nature of the radiation involved. The downward radiation can be measured but my understanding, at present, is that has no effect, as its frequency is too low to raise the temperature of matter at a warmer temperature.....2nd Law of Thermodynamics...true or false?
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  8. Re #153 Philippe Chantreau you wrote:- " How does Claes Johnson theory fare? The way I see it, according to his theory, a multiple mirrors type concentrating solar plant can not work." I have read Claes Johnson's paper and, although he has a differnt approach - more to do with him not being a native English speaker - I don't see how you can say a solar concenterator can't work. Solar concentrators work becaust the photons arriving at the Earth, although reduced in number by the inverse square law, still have the energy of the 5780K Sun; so if you use a mirror (or a lens) to concentrate sunlight you can, if there are no other losses(!) achieve an image of the Sun not just with its original brightness but with the original temperature (Don't, for goodness sake, look at such an image.)
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  9. Damorbel, I'm not saying that, Michele is. I know that these plants work, as I indicated. Johnson, according to Michele, says that "no energy" (that includes any and all) "can flow from a cooler object to a warmer one"; it means that no energy can flow from the colder individual mirrors to the hot concentrator. This is obviously false. I have not read the Johnson paper, I am just reflecting on the statement attributed to him by Michele. Awol, it seems there may be some confusion in how you consider your thermodynamics. If you accept that there is downwelling radiation (which you do), then you must also accept that the energy content of the surface increases as a result of that radiation. Whether it can be "directly measured" or not is irrelevant. And it does not mean that the direction of the net heat flow is going to change at any time. Everyone carrying on with the G&T stuff on the internet seems confused between heat (in thermodynamics, that means net heat flow) and energy (which can be almost anything). Heat must comply with the 3 laws. Energy can flow in a variety of ways, so long as the net heat flow of the system complies with thermodynamics.
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  10. Re #153 Philippe Chantreau you wrote:- " confused between heat (in thermodynamics, that means net heat flow) and energy (which can be almost anything). Heat must comply with the 3 laws. Energy can flow ." I hope I have a good grasp of your meaning because I do think you have a good understanding of the matter. Please do not think I am just being pedantic because all matters in thermodynamics and energy are closely related therefore words must be used with a precise meaning. So first off heat doesn't flow'; only fluids flow. This was the failure of the old caloric theory; caloric was supposed to be a fluid 'filling in the spaces' between the atoms and giving it the feeling of hotness. This theory came into question when it was realised that the friction involved in boring out a cannon barrel that caused it to get hotter; the temperature rise could be directly related to the (frictional) work done. Also hotter material weighed no more than when it was cold. At the time this was powerful evidence because Lavoisier had used a similar technique to disprove the phlogiston theory of combustion. A second, more modern, confusion; the one about heat meaning 'net heat flow'; a sort of term for energy 'in transit' (somehow). Let there be no doubt about it, heat is energy density where the energy is in the form of molecular motion, it is to be found in all materials above 0K. This energy density is the material's temperature, it is only related to energy by dividing the energy by the material's specific heat K = Q/C. As you say just saying 'energy' is far too vague, e.g. for mixtures of steam and water; water contains a lot of none-thermal energy in the binding force that make its molecules a liquid - this is the energy also called the latent heat of evaporation. But the binding force has got nothing to do with molecular motion, even though the energy it implies can only be overcome by molecular motion. In regard to this last matter, the heat of a water/steam continuum dose not increase as the % steam increases because the temperature doesn't change, only the energy in the system increases. That is why a water/steam mixture can be at equilibrium i.e. the temperature in the liquid is the same as the steam, so no energy transfer (no change in entropy).
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  11. Re #160 - should have been "Re #159 Philippe Chantreau"
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  12. damorbel "So first off heat doesn't flow'; only fluids flow" honestly I find it and the discussion on the caloric theory really pedantic. You confuse heat and internal energy. Here's the first quote I found just googling, but I urge you to check in a standard textbook:
    "Heat may be defined as energy in transit from a high temperature object to a lower temperature object. An object does not possess "heat"; the appropriate term for the microscopic energy in an object is internal energy."
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  13. Re #162 Riccardo you wrote :- "honestly I find it and the discussion on the caloric theory really pedantic." Um, well, yes; very interesting. Tell me do you also reject the conclusions that have been drawn in consequence of the failure of the 'caloric theory' to match scientific observations, such as the 1st law of thermodynamics, the conservation of energy etc.? You wrote also :- "You confuse heat and internal energy. Here's the first quote I found just googling, but I urge you to check in a standard textbook:" In #160 I was drawing a distinction between internal energy which causes a temperature change (heat) and internal energy that doesn't cause a temperature change, sometime (mistakenly) called 'latent' heat. How do you draw a distiction between the two? I have seen the sort of 'stuff' in the link you give and I often wonder how the idea came about. Of course latent heat is not the only manifestation of the inadequacy of the definition in your link. What about gases with different specific heats? Equal molar quantities of He, O2 and CO2 at the same temperature possess completely different amounts of thermal energy, can you say what their temperatures would be if they had the same (molar) internal energy?
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  14. This discussion would manage a great deal less misinterpretation if using an agreed text book on thermodynamics which includes the rigorous mathematical development. Then can be on "same page" as it were. What is you suggested reference damorbel?
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  15. damorbel "Um, well, yes; very interesting. Tell me do you also reject the conclusions that have been drawn in consequence of the failure of the 'caloric theory' to match scientific observations, such as the 1st law of thermodynamics, the conservation of energy etc.?" non sequitur "In #160 I was drawing a distinction between internal energy which causes a temperature change (heat) and internal energy that doesn't cause a temperature change, sometime (mistakenly) called 'latent' heat. How do you draw a distiction between the two?" you where not talking about this: "Let there be no doubt about it, heat is energy density where the energy is in the form of molecular motion, it is to be found in all materials above 0K. ". Please don't try to move away from what you said, it's pointless. As I alread said, check any textbook. Or you think you know better than textbooks?
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  16. AWoL, the answer is "false!" to your question "The downward radiation can be measured but my understanding, at present, is that has no effect, as its frequency is too low to raise the temperature of matter at a warmer temperature.....2nd Law of Thermodynamics...true or false?" Your rationale contains several misconceptions. The frequency of the downward radiation is not by itself the determinant of the resulting temperature of the matter that absorbs it. The temperature of that matter at a given moment in time is a consequence of the energy that matter contains at that time. The matter does not know or care how it got that energy. If a single photon of frequency F is absorbed by that matter, the matter's energy increases by a corresponding amount E. Imagine that instead the matter is hit by two photons each having a lower frequency such that they each have only half that energy (i.e., E/2). If those two low-energy photons both are absorbed by the matter, the matter will absorb the same energy E (i.e., 2 x E/2 = E) that it would get from absorbing the single original photon that carried energy E (i.e., 1 x E = E). The temperature of the absorbing matter is irrelevant to whether the matter absorbs any of those three photons. But even the total amount of energy absorbed is not the sole determinant of the matter's temperature. At the same time that energy is being absorbed, energy is being emitted by the matter. If every time energy E is absorbed, coincidentally that exact same amount of energy E is emitted simultaneously, then the net change in the energy contained by the matter is 0 (i.e., +E + -E = 0). If the amount of energy contained by the matter does not change, then the temperature of the matter does not change. If instead the matter is absorbing 0 energy and is emitting E energy, the matter's contained energy is reduced by E (i.e., +0 + -E = -E), which means the matter's temperature reduces. If instead the matter is absorbing E and simultaneously emitting only 70% of E, then the matter's net change in energy is an increase of 30% of E (i.e., +E - .7E = +.3E). That last sentence is why the greenhouse gas effect does not violate the 2nd law of thermodynamics. Matter on the surface absorbs some of the photons emitted by the Sun, thereby acquiring energy. The temperature of that receiving matter has no influence on whether a particular solar photon is absorbed, and therefore has no influence on whether that photon's energy is added to the energy the matter already has. Matter on the surface also absorbs some of the photons that are emitted by air molecules. The temperature of the receiving matter has no influence on whether each of those particular air-sourced photons is absorbed. The surface matter blindly absorbs photons from both sources. Does the surface matter's temperature increase when those absorptions happen? There is no way to know unless we also know how much energy the matter is losing at the same time, as I described above. One name for that is the surface "energy budget"--energy gained minus energy lost equals net energy change. If the surface matter is emitting more energy than it is gaining, its current energy content falls, so its temperature falls, despite the fact it is absorbing energy. If the surface matter is emitting less energy than it is gaining, its current energy content rises, so its temperature rises. Crucially, the gaining of energy is that total from all sources--Sun and air, radiation and conduction. The fact that the source of some of that energy is really hot (Sun) and the source of some of the energy is kind of cool (air) has played no role. Photons do not carry source credentials. It happens that the temperature of the surface matter does affect how much energy the matter emits. Starting from equilibrium (balanced budget: energy in = energy out), when extra energy comes in, the total energy content becomes higher than a moment before, which means the temperature is higher, which leads to the emission of more energy. If that extra incoming energy was just a single pulse, then the extra outgoing continues until all that pulse's energy has gone out. In the absence of an ongoing stream of "extra" incoming energy, the matter's energy then is again at equilibrium. In this pulse case, the matter's temperature only temporarily increased. The temperature affected the energy budget, but only by affecting the amount of outgoing energy, not by affecting the amount of incoming energy. If instead of a single pulse of "extra" incoming energy there is a steady stream of extra incoming energy--a step up in the incoming energy--then the temperature increase also is a step up, and the temperature stays at that higher temperature, once again at equilibrium with the new (larger amount) of incoming energy matching the new (larger amount) of outgoing energy. The energy absorbed during the step-up itself remains inside the matter; the energy gotten during the step up remains "trapped" by the matter. Still, the temperature of the matter has no influence on the amount of energy absorbed; temperature affects the energy budget's bottom line only because it affects the energy budget's outgoing part of the equation. Greenhouse gas warming of the surface works as that last paragraph describes. Where exactly in that mechanism do you see an opportunity for the 2nd law to interfere?
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  17. AWoL @ 155: I had prepared a rather detailed response, and mis-clicked on "click for tips &c." when I meant to preview the post. So consider this the poor cousin alternative. So I'll just suggest checking out the threads on this site: - Empirical evidence for warming. - Empirical evidence of human causality. And I believe any further discussion on CO2 as a trace gas should occur in a thread such as this one. The great thing about this blog is its reliance on - and its frequent refernece to - the peer-reviewed literature in the various threads regarding the evidence surrounding AGW. I brought up quantum & relativistic physics as examples of areas which often require starkly non-intuitive thinking to bring understanding, the sort of thinking where relying on instinct can lead one astray. I am sure there are many excellent sources of information on them, both online and in print.
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  18. Damorbel, although I brought up the subject, I don't want to be picky on words to the extreme. I think you make some valid points but I don't see that they are worth an argument. In the principles, I find nothing on which we disagree. If you don't like "flow", how about "net energy transfer"? As long as we know what our words mean, we can communicate. The problem with G&T associated blog discussions is that too many people use heat when they mean thermal energy, or energy, and do not realize that there is a difference between net and other energy transfers. Then they create a 2nd law violation where there isn't any. It matters little regarding the subject at hand. Tom summarized things rather well. My point was about what I see as an intrinsic inconsistency in Awol's reasoning. One can not say "I admit that there is energy transferred between the atmosphere and the surface" and at the same time deny that this makes the blackbody temp of the surface higher than it otherwise would be. Now, that would seem to be a true violation of the 2nd law! Whether or not it can be "directly" measured (whatever Awol meant there) would be a function of the measuring equipment, not of thermodynamics. As long as the net energy transfer is still in the right direction, there is no violation.
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  19. @ archiesteel: you can disagree with me on this subject but I refuse to turn the talk into a row.
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  20. Re #165 Riccardo you wrote:- "As I alread said, check any textbook. Or you think you know better than textbooks?" I'm quite sure you can find whatever you want in a textbook, lots of 'scientific' theories are published in text books, there many many books published with wonky ideas, a sure sign is when there is no evidence presented, typically 'heat is energy in transit' which by any standards is a meaningless, self-defining statement. One of the benefits of my education was the poor view taken by my teachers of the availble textbooks; we were encouraged to question all matters and our teachers responded (sometimes!) to challenges. scaddenp, this response should cover your #164 also ("This discussion would manage a great deal less misinterpretation if using an agreed text book").
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  21. #170, damorbel, now you're getting sloppy. You actually you can't find whatever you want in a textbook. I challenge you to find one that explicitly states or implies that the greenhouse effect is inconsistent with the second law. The equations will always say the same thing (pretty much along the lines of Tom's post above). It's not even that complex...just an energy budget. People do the same calculations when they balance their checkbook. Freedom of opinion is good, and you're welcome to it. But in science talk is cheap. If you are going to dismiss centuries of painful experiment, careful theory and thorough debate out of hand, then I am afraid the onus is on you to actually redo the experimental and theoretical work yourself. Only then will you be have something to contribute. Good luck with that.
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  22. damorbel - the theory of thermodynamics is set down as a large coherent body of knowledge and as a mathematical model, built up from the ground of measurement axioms. Within the body, you must have precise definitions of terms like heatflow on which the mathematics depend. The theory gives you the power to predict experiments which for a textbook case is verified countless times. When I ask for textbook, then I am wanting you to locate yourself within a coherent theory, so I can match terms into the mathematical framework. That gives us a basis for definition and also for discussing the foundational experimental work that the mathematics models. If you are doubt the theory of thermodynamics and present your own eccentric interpretations, then lets find the point of departure from the standard work. I'm used to Callen and derivatives but also more foundational works. What is your foundation?
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  23. darmobel oh, I see, textbooks are full of "wonky ideas", so we need to start from scratch to invent new science. It sounds great, we're going to get the Nobel price for this. Just a bit conceited but, who knows, it might work. Did your teacher also tell you why you should question textbooks? Because they're full of "wonky ideas" or because it's the process required for a deeper understanding? Probably this discussion should be moved to a different thread, something like "new ideas for the new millennium science" and continue here with the wonky old science.
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  24. Re #166 Tom Dayton you wrote:- "If instead the matter is absorbing E and simultaneously emitting only 70% of E, then the matter's net change in energy is an increase of 30% of E (i.e., +E - .7E = +.3E). That last sentence is why the greenhouse gas effect does not violate the 2nd law of thermodynamics." But this does not represent the GHE 'science'. If the material is, as you say "emitting only 70% of E" then it is colder than the material supplying the incoming photons, of course its temperature will rise! Further you wrote;- "The temperature of the receiving matter has no influence on whether each of those particular air-sourced photons is absorbed. The surface matter blindly absorbs photons from both sources." Yes, that is true. But you mustn't you also recognise that the energy of the photons emitted (by the receiving matter) is a strict function of 'The temperature of the receiving matter'? And this is how the e Yet further you wrote;- "The fact that the source of some of that energy is really hot (Sun) and the source of some of the energy is kind of cool (air) has played no role. Photons do not carry source credentials." This is entirely at variance with observation, it is contrary to the basics of quantum physics, starting with Einstein's observation that the emission of electrons from an illuminated surface did not happen at all unless the light had a wavelength shorter (frequency higher) than a particular value. The energy of a photon is defined by the frequency of oscillation of its source, the equation is E = hf where 'h' is the Planck constant. The 2nd law comes in when two bodies have different temperatures. If the temperatures are the same both bodies emit photons with the same energy. If there is an intermediate reflecting suface or one body is much bigger than the other not all the photons will be absorbed, some of the photons will miss or be redirected by the (partially) reflecting surface, they may even be redirected back to where they came from. However the net result is the same, the high energy photons from the hotter body, when absorbed will increase the energy in the cooler body; the lower energy photons (absorbed by the hotter body) will not be able to compensate the hotter body for its loss of energy contained in the (high) energy photons it has emitted; so the temperature of the cooler body rises and that of the hotter falls until they are equal. In the case of a planet the (warm) surface emits photons; if there is nothing in the atmosphere that absorbs/emits photons they go to deep space at 2.7K. Deep space emits photons at 2.7K that is how we know it is at 2.7K; some of these deep space photons are absorbed by the Earth's surface. If there is a GHG in the atmosphere it emits photons at, let us say 255K to deep space and absorbs some at 2.7K. There is a steady state, the temperatures are stable. The lower atmosphere (288K) will absorb some of the photons emitted by the GHGs (255K) but we know that the balance of temperatures will not rise because the atmosphere would then become more stable because convection currents would be suppressed. When considering the effects of radiation on the atmosphere you must not forget that there is one heating/trapping effect that does what I describe and is plain for all to see; it is the formation of the stratosphere due to the absorption of solar UV by O2 and O3; the consequent rise in temperature causes a classical inversion which stops convection, greatly reducing the turbulence found there. If there really was a rise in temperature due to a GHE, it would also show itself by producing an inversion.
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  25. Re #173 Riccardo you wrote:- "I see, textbooks are full of "wonky ideas"" You seem to have a belief system that requires text books to contain 'the truth'. But of course there are many books and scientific papers about theories (caloric, phlogiston, aether etc.) that have fallen by the wayside, How do you reconcile this fact with your (apparent) belief that books contain 'the truth'; even if only a scientific truth? What my teachers wanted me to do was to separate those ideas that were consistent with the (latest) scientific evidence. The best example in the current discussion is the requirement for believers in the GHE to accept thar the Earth emits (thermal) radiation 'like a black body and is the daft enough to continue by calculating the (pseudo) surface temperature on what they even admit is 'an assumption'*. How ridiculous can you get? Predicting doom on the basis of an assumption must surely be the ultimate unscientific activity. * Try page 2 of 'The Physics of Atmospheres' (3rd ed.) by John D Houghton, where he writes 'the left hand side [of the equation] [is] the radiation emitted by the planet assuming it behaves like a black body at temperature Te.' John D Houghton was a senior figure in the writing of at least the first two of the IPCC Assessment Reports, this is the so-called 'science' in text books about the GHE.
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  26. Re 172 scaddenp you wrote:- "you must have precise definitions of terms like heatflow... When I ask for textbook, then I am wanting you to locate yourself within a coherent theory " That 'heat flowed' i.e. it was some kind of fluid, was the basis of the caloric theory; it fell to bits because no measurements showed that there was in fact anything flowing. I you really are interested you may find in a good library (they may have to order it for you) "The Caloric Theory of Gases - from Lavoisier to Regnault" by Robert Fox; OUP 1971. In this book you will find a fascinating history of 'theories' of heat and the controversy they caused; it really is most interesting. For the rest as soon as you dee the expressin 'heat flow' you should realise that the author is confused and doesn't understand the matter. (I may well have used it myself, it is such a seductive phrase!)
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  27. damorbel "You seem to have a belief system that requires text books to contain 'the truth'". No darmorbel, this is your (ascientific) thought not mine. As I scientists i won't find the truth anywhere. But i do recognize the best knowledge available at the moment, easily found in thextbooks, from where we all should start. You missed this first step and took a weird path. This is confirmed by the rest of your comment and by the previous ones, you missed the first step of a deeper understanding of the current best available knowledge before trying the next step.
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  28. Damorbel, as I told you in another thread... if you want to prove the textbooks are wrong and you've uncovered the 'True science' you are never going to make your case by ranting on the internet. People will just look at the textbooks and say, 'Well according to this, people have been experimentally proving the existence of back radiation and greenhouse warming since Tyndall first did it in 1858'. That's over a hundred and fifty years of direct scientific practice saying you are wrong. You need to prove otherwise within the scientific community (aka, by publishing evidence to the contrary in science journals and having your findings validated) or you will just continue to be dismissed.
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  29. Re 177 Riccardo you wrote:- "But i do recognize the best knowledge available at the moment, easily found in thextbooks," If you want to find 'the best knowledge' I cannot do better than recommend you adopt my practice of reading original texts of those credited with being the originators of the science in question. For example, have you read Max Planck 'The Theory of Heat Radiation'; Albert Einstein papers on the quantum effect 1905, 1909, and 1917; G R Kirchhoff 'On the Relation Between the Emissive and the Absorptive Powers of Bodies for Heat and Light'. The really interesting thing about Planck and Einstein is that they freely acknowledge the merit of the work of their predecessors, Kirchhoff in 1862, Planck in 1901 and Einstein in 1905,1909 and 1917. Until you have read these works as a minimum your knowledge and appreciation will be substantially less than mine. I hope you enjoy them as much as I did. Oh, I nearly forgot J.C. Maxwell, a copy of his major work 'Theory of Heat' is available on line for about £6.29
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  30. Re #178 CBDunkerson. Have you read Tyndall's papers, Arrhenius' paper? Have you studied the paper of Callendar? Do tell me about what you have read that convinces you so strongly.
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  31. Damorbel writes: "If you want to find 'the best knowledge' I cannot do better than recommend you adopt my practice of reading original texts of those credited with being the originators of the science in question." Horrible idea. We should go to Newton for the best science on gravity? Darwin for the best science on evolution? Fourier for the best science on the greenhouse effect? I think these examples show what nonsense that position is. Essentially you are saying that we should ignore everything which has been learned since and go back to the very first 'flash of inspiration' where a scientist had uncovered something new and was speculating about possible details and their implications. They invariably made many incorrect guesses and assumptions precisely because what they uncovered was so new. Yes, there is value in reading the original work, to see how they arrived at their conclusions. However, taking the earliest small steps in a new field as the "best knowledge" of that field over the results of decades and centuries of further research is pure upside down bizarro world madness.
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  32. Re #181 CBDunkerson you wrote "Horrible idea. We should go to Newton for the best science on gravity? Darwin for the best science on evolution? Fourier for the best science on the greenhouse effect?" Yes! Yes! Yes! But since your response does not identify the publications/authors I am supposed to be reading to grasp your position; your response is of little use. Do you mean that J. Houghton's idea that Earth's temperature calculation (and that of all other GHE scientists) based on a 'black body assumption' is superior to Kirchhoff's careful arguments? Really CBDunkerson, I suggest it is quite reasonable to ask for something better than 'a black body assumption' before supporting an economy shattering 'theory' of AGW!.
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  33. Re #181 CBDunkerson you wrote "Horrible idea. We should go to Newton for the best science on gravity? Darwin for the best science on evolution? Fourier for the best science on the greenhouse effect?" Yes! Yes! Yes! And you hang your ideas (in #178) on Tyndall et al at the same time as you write:- "'Well according to this, people have been experimentally proving the existence of back radiation and greenhouse warming since Tyndall first did it in 1858'. That's over a hundred and fifty years of direct scientific practice saying you are wrong." This is extremely "flexible" (or selective) argumentation,don't you think? We have moved on from Kirchhoff, Planck and Einstein but not from Tyndall! Do please explain why you think Tyndall's interesting but minor papers should take precedence.
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  34. #179: "recommend you adopt my practice of reading original texts of those credited with being the originators of the science" The difficulty with reading 'the originators' is that it's easy to miss one or two points. For example, from Max Planck's The Theory of Heat Radiation: ... the state of radiation at a given instant and at a given point in the medium cannot be represented, as can the flow of heat by conduction, by a single vector ... And Jean Joseph Fourier'sThe Analytical Theory of Heat, wherein we find these entries: Notion and measure of the flow of heat Analytical expression of the flow in the interior of any solid. Measure of the quantity of heat which crosses an edge or side parallel or perpendicular to the base. This expression of the flow suffices to verify the solution But as we learned here, heat does not flow, only fluids flow. Thus Planck and Fourier were mistaken and the great and mighty damorbel stands alone. Yet when asked to produce a single textbook -- his choice -- so that a conversation could proceed with at least a common vocabulary, damorbel resorts to this bit of pure puffery: "my practice of reading the original texts"! On this thread and the prior 2nd Law thread, damorbel put forth enough of his views on thermodynamics and science in general to write his own textbook. Surely that would be a more rewarding endeavor than wasting his time here. Alas, textbooks are usually written by more than one author and are always reviewed. Yes, there are mistakes that pass through, but can damorbel find just one to recommend?
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  35. Re #184 muoncounter you wrote:- "The difficulty with reading 'the originators' is that it's easy to miss one or two points." and :- "Thus Planck and Fourier were mistaken and the great and mighty damorbel stands alone." Indeed, from these one or two points in a translation you deduce that Planck was an aficinado of caloric theory. Um, er, do you have any thing else in support of caloric? As for poor old Fourier, he was living in a time that caloric had few rivals! Further you wrote:- "Yes, there are mistakes that pass through, but can damorbel find just one to recommend? " The best technique is to learn the fundamentals and see what the author writes, I don't know of an error free book. There is absolutely no point in following what you find in a book slavishly. For examples, do you subscribe to John Houghton's theory that you can calculate a planet's temperature on the assumption that it is a black body without the slightest justification? If you do then you are following indeed 'like a slave'.
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    Moderator Response: [Daniel Bailey] You tread dangerous ground. Keep it clean and adhere to the Comments Policy. Any future examples of comments like this one will be deleted. Thanks in advance for your compliance!
  36. darmobel "Until you have read these works as a minimum your knowledge and appreciation will be substantially less than mine." wow, it sounds really, really, conceited. Just to remind you, you're not talking in the name of Plank or Einstein or Maxwell. You're talking for yourself aginst the understanding of generations of physicists.
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  37. Damorbel: "The lower atmosphere (288K) will absorb some of the photons emitted by the GHGs (255K) but we know that the balance of temperatures will not rise because the atmosphere would then become more stable because convection currents would be suppressed." You seem to be saying the following: 1. C02, CH4, and H20 absorb and emit in the troposphere. 2. C02 and CH4 absorb and emit in the stratosphere. 3. If levels of these gases are stable, the planet will have a stable atmospheric temperature. Convection will occur as we know it. 4. If levels of these gases are increased, the troposphere will, uh, energy up, convection will decrease, and more energy will be carried to the stratosphere where it will be radiated more easily out into space. This release of energy will allow convection to once again take place and return the planet to the current, stable state. Is this your model?
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  38. Re #186 Riccardo you wrote:- "You're talking for yourself aginst the understanding of generations of physicists." Sorry, I don't understand how by recommending a minimum of Planck or Einstein or Maxwell I can possibly be against 'generations of physicists'; can you explain please?
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  39. Damorbel "Really CBDunkerson, I suggest it is quite reasonable to ask for something better than 'a black body assumption' before supporting an economy shattering 'theory' of AGW!." Yes, we could measure the outgoing radiation and see if it followed the blackbody assumption... ...which it clearly does. (blackbody lines dotted, solid line measured 20km looking down over arctic ice) Why you continue to state that the blackbody assumption is wrong in such contemptuous language when it's clearly valid is a question only you can answer. However, I suspect there may be a clue in your "an economy shattering 'theory' of AGW!. "(my emphasis) Unfortunately, physics doesn't respond to political polemic. Could I politely ask that you take some time to honestly reflect on how likely it is that you are right on this and look at your own arguments sceptically.
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  40. #185: Please refrain from accusations of 'slavish behavior.' That's enough to get your comments deleted; the speed at which you reverted to such is also a testament to the poverty of your overall position. You were asked to identify a textbook solely for the purpose of a identifying a common language for discussion and have thus far declined, because you can't find one that is 'error free'. I suggest that your fear of identifying a source for common language is that your semantic distinctions will evaporate in the glare of daylight. For example, "heat transfer, also known as heat flow, heat exchange" are well-understood equivalencies in common usage. So, under 'damorbel's law', we find yet another 'mistaken' originator. Einstein and Szilard's refrigerator patent contains 3 uses of the term 'heat exchange' and two of the words 'heat exchanger'. If there are neither 'heat flow' nor 'heat exchange', why does Einstein use a 'heat exchanger'? Either the meaning of 'heat flow' transcends the concept of caloric or 'damorbel's law' has an exception. But that's off topic. This thread doesn't need to be mired in your pedantry.
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  41. damorbel it's your understanding of those great physicists and pretending that I didn't read them and that you know better than me for ths reason. Anyways, this discussion has taken a dangerous slope of personal attacks. I'd invite everybody to end it here before it badly derails.
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  42. Re #187 DSL you wrote:- "C02 and CH4 absorb and emit in the stratosphere." The stratosphere is formed by O2 & O3 absorbing UV coming from the Sun which heats it, giving it its characteristic temperature profile. Now the question is, why doesn't back radiation, which originates from GHGs cause similar heating by being absorbed by the (relatively) uniform GHG distribution in the troposphere? For the rest, the Sun's energy comes in in a very non-uniform way, strongly at the equator and much less at the poles. The Earth radiates to a more or less uniform 2.7K thus there is a thermal gradient over the surface from the tropics to the poles. This gradient causes fluid flow in both the atmosphere and the oceans, the fluid flow tansports heat over the surface thus giving us climate and weather. Convection has a smallish role in climate, transporting heat from the surface into the atmosphere where it subsequently is either radiated to deep space or transported polewards. Heat from the Sun is also transported to the poles by ocean currents. The thing about convection is its very variable nature. When a lot of warm tropical surface water is drawn together by surface winds, a dynamic feedback takes place as convection increases, fed by the thermal energy contained in the surface water, producing spectacular hurricanes. A similar effect produces tornados over land.
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  43. @damorbel: "before supporting an economy shattering 'theory' of AGW!" Please provide concrete evidence that adressing AGW would "shatter our economy." That seems to be political opinion, not a rational assessment of reality. That could explain why you are resorting to inflammatory language after failing to produce any rational explanation as to why AGW would violate the 2nd Law of Thermodynamics. In other words, you have failed to present a convincing case. At this point, all you seem intent on doing is derailing the debate. Please stop.
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  44. Re 189 VeryTallGuy I can see absolutely nothing in your diagrams that shows the GHGs have the characteristic emission spectrum of a black body. The dotted lines are only there as a reference to what a black body spectrum looks like. The heavy black lines are (or are very similar to) the GHG radiation spectrum and it fluctuates wildly, going almost to zero between 600cm^-1 and 700cm^-1. This is the well known window where radiation from the Earth goes directly to deep space, GHGs do not have any effect in this region.
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  45. @michele: the issue is not that I and other disagree with you, it's that you do not present compelling responses to the counter-arguments being presented to you. I'm not looking for a fight, but I'm tired of people coming here trying to challenge the science when it's clear they haven't done their homework first.
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  46. Damorbel, I cited "over a hundred and fifty years of direct scientific practice" ... "since Tyndall" and you rewrote this as me citing just Tyndall; "Do please explain why you think Tyndall's interesting but minor papers should take precedence." I don't think that. I think that the 150+ years of science consistently verifying Tyndall's work should take precedence. Tyndall was the first to show experimentally how 'greenhouse gases' cause the 'greenhouse effect' (though he did not use either term)... but his instruments were not accurate enough to get precise readings of the magnitudes involved. Thus, we should not go to Tyndall for that information... hundreds of better sources are now available. By your 'logic' we should look ever backward to more and more limited understandings of science for the answers. Clearly the ultimate authority on all sciences would be the pre-caveman who developed the first tool by picking up a stick and hitting something with it.
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  47. "The stratosphere is formed by O2 & O3 absorbing UV coming from the Sun which heats it, giving it its characteristic temperature profile." Damorbel, are you suggesting that CO2, CH4 and H2O are not present or do not absorb/emit in the stratosphere? Why would that be? There is a considerable body of litterature showing that they are present and absorb/emit as expected.
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  48. Re #196 CBDunkerson you write :- "you rewrote this as me citing just Tyndall." Feel free to add who you like, I cannot do this for you. Meanwhile, if you think name dropping like this is a substitute for arguments, then what about Boltzmann, Joule, Clausius, Kelvin and many more who made remarkable contributions to thermodynamics. You will be hard pushed to discover anything of substance in their work that supports the strange predictions of AGW. The troposphere is colder than the surface below it, nobody contests this. That is all that is neccesary to destroy the hideously expensive CO2 reduction policies required to save us from AGW.
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  49. damorbel #198: "The troposphere is colder than the surface below it, nobody contests this. That is all that is neccesary to destroy the hideously expensive CO2 reduction policies required to save us from AGW." Numerous people, including me, have repeatedly shown you conclusive proof to the contrary. Your refusal to see (or address) those proofs is "all that is necessary" to demonstrate that you cannot make your case.
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  50. Re #197 Philippe Chantreau you write :- "Damorbel, are you suggesting that CO2, CH4 and H2O are not present or do not absorb/emit in the stratosphere? Why would that be?" I don't think any of the gases you mention are responsible to a great extent for absorbing UV in the stratosphere. It is O2 (diatomic oxygen) that absorbs UV at 200microns and below; this creates two separate (monatomic) oxygen atoms which then react with O2 (diatomic oxygen) to form O3; which is actually triatomic oxygen or perhaps more familiar with the name ozone.
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