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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.

Last updated on 22 October 2010 by TonyWildish.

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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 1151 to 1200 out of 1406:

  1. TOP - if the article doesnt convince of the nonsense in this paper, try the more exhaustive treatment at science of doom. Quoting G&T is crank-alert material. Like any science, if your theoretical prediction is at odds with reality, then you need to fix the theory.
  2. @1150,355 muoncounter
    I looked at a particular reference you cited, W. M. Connelly, June 2000 in which Connelly takes exception to Woods (1909) statements in the 2nd to the last paragraph while disregarding the implications experiment with the rock salt greenhouse. G&T performed the same experiment and got the same results as Wood. Note: Both G&T even refined the experiment so that the two "greenhouses" achieved much closer agreement in temperature by blocking IR from entering the rock salt greenhouse. Since Connelly was taking exception to the 2nd to the last paragraph and not the results or implications of the experiment it isn't much of a rebuttal. The results of the experiment which Connelly seems to be in agreement with is that the "greenhouse" effect has nothing to do with radiation being trapped on it's way back to space which is born out by the fact the plate glass is perfectly opaque to IR while rock salt is perfectly transparent to IR.
    Third, in contradiction to his assertion about "the very low radiating power of a gas", the troposphere is largely opaque to infra-red radiation, which is why convection is so important in moving heat up from the surface. Only in the higher (colder) atmosphere where there is less water vapour is the atmosphere simultaneously somewhat, but not totally, transparent to infra-red and thus permits radiation to play a part. [bolding is mine for emphasis]
    The "greenhouse" effect has everything to do with the prevention of convection from cooling the surfaces on which radiation impinges. In other words the AGW crowd in incorrect in applying the term "greenhouse effect" to anything to do with trapping radiation. That pretty much renders useless much of the discussion in this thread having to do with radiation. And as an added bonus Connelly attributes the opaqueness of the atmosphere to IR to water vapor, not CO2

    I will also add that if anything was done incorrectly in the experiments of Wood, G and T, it was in not also measuring the pressure and hence the enthalpy change inside the greenhouse.

    And I have from time to time done an experiment of my own that contradicts Connelly's assertion that the troposphere is opaque to infrared. I simply went outside with an non-contact IR thermometer and pointed it at the sky on a clear day and a cloudy day. On a clear day, even with sun at noon you get something on the order of -55F while on a cloudy day you get something on the order of 32F. In fact today, while it is lightly raining the "sky temperature" is 27F. So on a clear day I can easily measure the temperature of the stratosphere from the ground with an IR thermometer and on a cloudy day I can measure the temperature of the bottom of the clouds. That is hardly a troposphere opaque to IR.

    So you have to deal with two experimental pieces of evidence that show that Connelly is right and in agreement with both Wood and G&T, that is, convection or the lack thereof, not radiation that is responsible for controlling the temperature in the atmosphere.

    G&T, Connolly and Wood are in agreement that "greenhouse effect" is a misnomer and should not be used in the context of global warming. Greenhouses warm because convection is prevented and not because IR radiation is blocked. There is no "greenhouse" effect in the atmosphere. This is not denialist, it is experiment.
  3. 105, TOP,

    The Wood experiment is invalid and you misunderstand Connelly.

    SkS will have a post on it soon, but in a nutshell the problem with the experiment (actually, there are a few) is that the model is not an accurate representation of the atmosphere exactly because convection and other mechanisms in the experiment are allowed to heat the glass and rock salt plates, which removes any temperature gradient between the heated "surface" and the covering "top of atmosphere".

    Basically, the glass and rock salt both radiate at the same temperature as the inside of the box because they've been allowed to warm by means other than radiation. The atmosphere does not work this way, and the model represented by the experiment therefore does not accurately represent that actions of the atmosphere. More importantly, the experiment is therefore not properly controlled to be certain that the effect being measured is only that of infrared radiation versus other means.

    It basically tests if convection occurs in a closed box -- not a very useful thing to know.

    To perform the experiment correctly the transfer of radiation by means other than radiation must be inhibited (as it is in the atmosphere, where convection is not efficient or active enough to transfer that much energy to the point in the atmosphere where heat radiates away).

    In the case of the more correct experiment, the rock-salt plate will remain cool and IR will be emitted through it according to the temperature of the "surface" which is heated only by the incoming short-wave radiation, while the surface within the other box will heat further until an equilibrium is reached where the "surface" warms further than the rock-salt box and the glass plate itself has warmed — purely through absorbing IR — and is emitting infrared both up and down.

    On your own experiment... you are not measuring the temperature of the stratosphere. The air around you is densely packed with CO2 and H2O which are radiating in the infrared and contaminating your experiment. You are merely measuring the emissions of the atmosphere immediately above you.
  4. TOP:

    Even contrarian scientist Roy Spencer points out that the physical basis for global warming (outgoing longwave infrared radiation being trapped by the atmosphere) is correct.

    Both surface-measured backradiaton from the atmosphere and satellite-measured reduction in radiation at greenhouse gas-related frequesncies are empirically documented in the literature.

    The simple fact is that physical theory, experiment, and empirical evidence show that, however misnamed, greenhouse gases in the atmosphere trap outgoing heat and cause warming.

    Also, did you not actually read the quote you cited? It states, right there that "the troposphere is largely opaque to infra-red radiation". How could that be, I wonder?
  5. @1150,355 muoncounter
    I'm talking about those responding to the original post. In fact I wonder if the OP actually read G&T. As for comment #2, that post says G&T is completely wrong. That is a pretty broad statement. It means that the experiment that they did to show what the greenhouse effect is was wrong. And it means that in your quote of Connelly, he was wrong.

    The posts seem to wander away from dealing with G&T ad nauseum.
  6. @1153 Sphaerica
    I'm glad you agree with G&T. The term "greenhouse" is a misnomer when talking about the atmosphere. G&T propose using the term "atmosphere effect".
    Fleagle and Businger (1963) [125] devoted a section of their text to the point, and suggested that radiation trapping by the Earth’s atmosphere should be called ‘atmosphere effect’ to discourage use of the misnomer. Munn (1966) [126] reiterated that the analogy between ‘atmosphere’ and ‘greenhouse’ effect ‘is not correct because a major factor in greenhouse climate is the protection the glass gives against turbulent heat losses’.[G&T quoting Lee, 1973]"Falsification Of The Atmospheric CO2 Greenhouse Effects Within The Frame Of Physics", Gerlich and Tscheuschner, 2009, p37
    Further, the purpose of the Wood experiment was to determine whether it was radiation or convection that caused a greenhouse to warm. The results of the experiment were that a)it was convection, or the lack thereof that caused the greenhouse to warm and b)the heating of the greenhouse was influenced by IR from the sun causing the rock salt greenhouse to be warmer since rock salt allowed more IR radiation into the greenhouse.
    When exposed to sunlight the temperature rose gradually to 65◦C, the enclosure covered with the salt plate keeping a little ahead of the other, owing to the fact that it transmitted the longer waves from the Sun, which were stopped by the glass. In order to eliminate this action the sunlight was first passed through a glass plate.[bolding mine][G&T quoting Wood, 1909]"Falsification Of The Atmospheric CO2 Greenhouse Effects Within The Frame Of Physics", Gerlich and Tscheuschner, 2009, p33
    Indeed, if the atmosphere were opaque to IR (longer wavelengths) we would expect global cooling based on this experiment.
    Response: [JH] There is no need for you to use a small font size for citations. If text is so tiny to be unreadable, it has no value.
  7. @1154 Composer99
    My experiment with the IR thermometer showed that the troposphere is not opaque to IR.

    Someone mentioned that I was measuring the temperature of the air around me with the IR thermometer. That is incorrect, I get essentially the same readings on a clear day whether the outside temperature is 90F or 20F. When clouds intervene the sky temperature goes up because the bottom of the clouds is lower and the clouds have to be at a temperature above freezing to exist. So, Connelly was wrong to say the troposphere is opaque to IR.

    G&T also talk about this in their discussion about how there can be frost on the ground when the air temperature is above freezing.
  8. I can't belive that the meme "greenhoue effect is a minomer" keeps poppping up. It really tells nothing about the science and is a distraction that no one nedd, not even the sceptics/deniers. If Arrhenius (who probably was the first to use this analogy) knew, I'm sure he would not use it.

    And who's going to tell Tyndall of the new findings that "That is hardly a troposphere opaque to IR"?

    Luckly, we have comforting breking news: "Greenhouses warm because convection is prevented and not because IR radiation is blocked." Who could immagine that!

    Sorry for the sarcasm, TOP. But really the knowledge of the physics of the atmosphere and of radiation is way beyond that. Maybe you're right that it's not denialism but sure enough it's not "experiment" either.
  9. TOP, the term "greenhouse effect" is perfectly legitimate and useful for its intended use as a teaching and communication analogy for the high level mechanism: More energy comes in than goes out.

    You are obsessing about something of absolutely no consequence.
  10. TOP,

    You put words in my mouth. I never said the term "greenhouse" was a misnomer. I'm not saying I agree or disagree, because as Riccardo says, who the h-e-double--climate-hockey-sticks cares? It's a pointless debate.

    But you seem to have missed the point. Yes, you understand the purpose of the Wood experiment, but you have failed to understand why the design of the experiment was flawed. Please go back and read what I wrote. You are completely missing everything.

    As far as an IR-opaque atmosphere leading to global cooling... how the h-e-double-climate-hockey-sticks do you get that?
  11. TOP#1157

    IR handhelds don't work that way. If you're not pointing at an object, it's not measuring anything. To claim a handheld can take the temp of the stratosphere is preposterous.
  12. TOP, G&T spend about 18 pages telling us what is already well known and understood as if they had some shocking new insight before getting into their own misconceptions. Science has known for a long time that the "Greenhouse Effect" is poorly named. The article is only about what is new that G&T assert.
  13. So, on the one hand, we have:
    - empirical findings of IR backradiation from the atmosphere measured from the surface;
    - empirical findings of IR wavelengths being blocked by IR-trapping (aka greenhouse) gases measured from satellites
    - empirical findings showing an energy imbalance at top-of-atmosphere, measured from satellites
    - empirical findings showing extra energy is rapidly building up in the Earth climate system (e.g. measurements of ocean heat content, ice melt, temperatures climbing)
    - other empirical markers of a rapid warming from meteorology and from ecology
    - experiment and known physics backing up all of the above

    And on the other hand we have TOP trying to tell us all that is wrong, wrong, wrong based on a few handheld IR thermometer measurements.
  14. @1162 scaddenp
    Maybe you can tell me in what section of their paper they propound a misconception? The paper has 115 pages. I'd like to know one misconception and the page and section it occurs in. Then we can have a meaningful discussion.
  15. Gee, where to start? Did you look at SoD?
    How about (from SoD)
    "In any case, a larger portion of the incoming sunlight lies in the infrared range than in the visible range. In most papers discussing the supposed greenhouse effect this important fact is completely ignored." Talk about a completely unsupportable (and wrong assertion).

    However, the core would be about validity the RTE and (to quote SoD) their "imaginary 2nd law".

    Again, conventional text book physics has no problem producing predictions that match observation. If G&T were right, then this would be impossible. I'll stick with the text book thanks.
  16. "the clouds have to be at a temperature above freezing to exist."

    That is incorrect. Temperature has to be at or below the dew point for any visible moisture to exist. Clouds can and do exist at temeratures at or below freezing. Liquid water can exist at air temperatures as low as -40 deg Celsius.
  17. TOP @1152:

    1) You misquote Connolly as saying the troposphere is opaque to IR radiation. What he actually said is that it is "largely opaque to IR radiation". (My emphasis). That is easily verified by examining the downward IR radiation at the surface, as for example in these two spectra:



    You will notice that even with low humidity (Barrow Island), the atmosphere is essentially opaque to IR radiation outside the bands between wavenumber 800 and 1000, and between 1100 and 1200. With high humidity (Nauru) there are significant local emissions even in those bands.

    These facts were first discovered by the US Air Force, which conducted experiments in the IR transmission properties of the atmosphere so that they could effectively deploy heat seeking missiles. Consequently heat seeking missiles, and IR cameras, and IR thermometers are all tuned to the bands of low IR emission by the lower atmosphere. This model, for example, is tuned to the entire band of low atmospheric emissions, 8 µm to 14 µm (see spectral response under specifications).

    Arguing the atmosphere is not largely opaque to IR radiation because you can use an instrument tuned to the wavelengths in which the atmosphere least opaque is bizarre, although certainly not unique to you among fake skeptics. Neither is misquoting a source to strengthen your case. I hope both were accidental, and that you will now recognize that Connolly's claim was correct.

    2) If known temperatures and humidities (from observations are fed into a Line By Line (LBL) radiation model, the result looks something like this:



    This is the result of an actual comparison between a LBL model and observations over the Gulf of Mexico.

    This is the same comparison with theoretical and observed spectra offset for clarity:



    Here is a detail of the first image with black body curves shown for clarity:



    You will notice that the absorption band of CO2 emits radiation consistent with a black body curve of 220 degrees Kelvin. As the Earth must on average emit energy equivalent to a black body curve of 255 degrees K to not continuously gain heat, it follows that that low emission must be compensated for by a higher emission somewhere else. Because of the absorption by water, the band in which that higher emission can come from is largely restricted to the area of IR transparency, ie, in which the radiation is coming from the surface. In order to emit IR radiation with a black body equivalence greater than 255 degrees K, the surface of the Earth has to be at at temperature greater than 255 degrees K. Ergo, the absorption of IR by CO2 forces the temperature of the surface to have a temperature greater than that which it would have had in the absence of the CO2.

    That was all simple physics, and follows immediately from the observed emissions, and the conservation of energy. No amount of experimentation with a toy box can prove these observations false, and therefore not amount of experimentation with a toy box can show that the greenhouse effect does not exist.

    In case you think that that observation/model comparison was cherry-picked because it was an unusually good fit, here is the scatterplot of 134,862 comparisons between measured, and modeled Outgoing Longwave Radiation (OLR) measurements:



    3) A very minor point, but Wood's experiment was designed to show whether or not greenhouses warmed because of increase IR back radiation from the glass panels. His experiment successfully showed that they do not. It does not show, and is incapable from its design of showing, that the greenhouse effect does not exist. People who think it does do not understand the physics of the greenhouse effect.

    In order to successfully test whether a slab model of the IR effect is physically sound, you need to isolate the radiated surface (floor of the box) and the window (top of the box) by means of a vacuum. I do not believe it is possible to model the actual greenhouse effect as seen in Earth's atmosphere in so small a physical model.

    4) Names are acquired through history and retained from convenience. Yes, the "greenhouse effect" is not in fact the effect that warms greenhouses. But neither are tin cans made from tin, nor are rubber ducks either rubber, or ducks. Get over it. If such trivia are all you have to criticize the theory, then that theory is very well grounded indeed.
  18. @1160 Sphaerica
    The atmosphere is densely packed with water vapor and CO2? Just what is the volume percentage of CO2 in the atmosphere?
    a) 40%
    b) 4%
    c) .4%
    d) .04%
    e) None of the above
    Hint: You will find the answer in G&T, Table 4, p.8.

    And I am glad you agree with G&T that the box experiment is not a good representation of the atmosphere. It is good to know G&T got something right. Now if you had said the box experiment did not agree with how greenhouses operate that would be a great flaw in G&T.
    2.6 Glass house summary

    It is not the “trapped” infrared radiation, which explains the warming phenomenon in a real greenhouse, but it is the suppression of air cooling."Falsification Of The Atmospheric CO2 Greenhouse Effects Within The Frame Of Physics", Gerlich and Tscheuschner, 2009, p34

    The purpose of the Wood experiment is singular, to determine whether radiation or convection controls the temperature of the air inside the box. The simple conclusion is that radiation has nothing to do with it. Glass completely blocks the escape of radiation. Rock salt allows all radiation to pass freely. With rock salt the box actually heats faster because the IR from the sun is allowed in as another forcing.

    @1157 muoncounter
    Sure I know how IR thermometers work. Can you explain to me how not to point an IR thermometer at something? Is the stratosphere a vacuum? Can you explain why pointing the IR thermometer at the sun does not register 5,800K?

    The IR thermometer integrates thermal energy within it's view cone by focusing it onto an IR sensitive transistor after filtering visible light. It uses the Stefan-Boltzmann law to back out the temperature (T&G eq.28, p.20). It doesn't care where the thermal energy comes from. Thermal energy doesn't carry little tags on it with it's origin stamped on it. Since pointing it at zenith allows it's view cone to take in the whole sky the area/radiant energy being integrated compensates for the low emissivity of the gases in the atmosphere above it. After all the reciprocal of the area of a 15deg included angle cone 29,000 ft away is about 2.2E-8 which is on the order of magnitude or smaller than the emissivity of the stratosphere. The farther away, the greater the area seen, and the more the low emissivity is compensated. The sun's emissivity is extremely low and it's apparent area is extremely small so it just doesn't register. So it is no coincidence that taking a reading of clear sky registers -55F or so on the IR thermometer which is experimental evidence that my hypothesis is right. Similarly when cloud if fully covering the view cone the thermometer measures something around freezing which is what I would expect cloud temperature to be (rain clouds anyway).

    And this line of reasoning is further backed up by the frequent formation of frost on my cars even when the air temperature is above freezing. The surface of the car and windshield radiates heat to a colder object, that being the stratosphere and space. If the car is under a tree, the frost won't form.

    In fact wikipedia mentions that IR thermometry is used to detect the presence of clouds. Same thing that I am doing.
  19. My hat off to you Sphaerica for your patience!!!

    TOP, if your experiments are so great that invalidates more than a hundred years of knowledge go ahead publish and become famous. Atmosphere is NOT opaque no matter how you look at it. The spectrum emission might look continuous but it is not. Atmosphere is NOT densely packed with water vapor. It is densely packed with N2 and O2. At 20oC the saturation at sea level is around 20,000 ppm of water, and we are now around ~400 ppm of CO2. I would say HARDLY densely packed. Actually above a certain height there is ONLY CO2 in the atmosphere (from the GHG ensemble). CO2 is much better well distributed compared to H2O.
  20. TOP. Have you read the notes at the bottom of this page - and followed the links?

    Could save you a bit of grief.
    Response:

    [DB] The NOTES sections are not accessible to the lay reader.

  21. TOP#1168: Thanks for tech summary on IR thermometry. I refer you to the specs for the Fluke 62, a top-of-the-line handheld: It reads as low as -30 C, a tad above the -48 C (225K) that you report for the temperature of the stratosphere. Also note "this rugged, compact thermometer takes accurate readings from up to six feet away." The D to S ratio is given as 10:1, so at 72 inches, you're reading a circular area 7.2 inches across. Beyond that, who knows what you're seeing?

    As for frost forming on the ground, surface air temps are standardized about 1.5 m above ground in screened enclosures - so that surface stations aren't contaminated by false readings. Cold air sinks. But you knew that already.

    You might read the text below the words 'Good Response by John Farley' in the Notes below, which gives specific examples of GT errors.
    Response:

    [DB] Please note that the NOTES section described by muoncounter is not viewable to the lay reader, so the relevant section is reproduced below:


    Good response by John Farley: Cockburn is impressed by a scientific argument, claiming that the greenhouse effect violates the Second Law of Thermodynamics.  He relies on a publication by Gerlich and Tscheuschner (GT), "Falsification of the Atmospheric CO2 Greenhouse Effects within the Frame of Physics."5  However, the greenhouse effect can be easily demonstrated in the laboratory.  The BBC broadcast a tabletop demonstration of the greenhouse effect, which can be found at the BBC website (at <news.bbc.co.uk/2/hi/science/nature/8394168.stm>).  The video, a little over 2 minutes long, is well worth watching.  Physics is an experimental science, and if theory disagrees with experiment, the theory must be flawed.

    But beyond noting that the GT theory is refuted by experiment, it is worthwhile examining where GT went wrong.  They claim that greenhouse gases in cold upper atmosphere cannot possibly transfer heat to the warmer earth, without violating the Second Law of Thermodynamics.

    Let's be clear about what Second Law of Thermodynamics does and does not say.  Suppose that you have two objects at two different temperatures, and suppose that light (visible or infrared) from either object can reach the other object.  There will be a flow of heat from the hot object to the cold object and a smaller flow of heat from the cold object to the hot object.  There are thus heat flows in both directions: from hot to cold and from cold to hot.

    The Second Law says that the flow of heat from hot to cold is greater than the flow of heat from cold to hot.  Hence the net flow of heat is from the hot object to the cold object.  Note that the existence of a smaller flow of heat from the cold object to the hot object does not refute the Second Law.

    At this point, we return to Cockburn's argument (from GT).  Heat flows from the warm earth to the cold atmosphere and also from the cold atmosphere to the warm earth.  (Heat also flows from the cold atmosphere to outer space, which is even colder.)  The flow of heat from the earth to the atmosphere is greater than the flow of heat from the atmosphere to the earth, so the net flow of heat is from the earth to the atmosphere.

    But there is also a (smaller) flow from the atmosphere to the earth.  This smaller flow keeps the earth warmer than it would be if there were no greenhouse gases in the atmosphere.  This is what the greenhouse effect is all about.  On this point, Cockburn has been misled by GT, who have advanced degrees in physics but have made a serious mistake in thermodynamics.

    Readers with a background in physics and calculus can read a comprehensive refutation of the GT paper by Arthur P. Smith, "Proof of the Atmospheric Greenhouse Effect."  Smith's article begins: "The results presented here are not new."  Indeed, they are over a century old and found in standard textbooks.  Smith has presented the subject in great detail in order to answer objections raised by GT to the treatment found in standard textbooks.

    The greenhouse effect has been known for over a century.  The greenhouse effect is quite a big effect: the Earth's surface is about 59 F warmer than it would be in the absence of greenhouse gases in the atmosphere.  The greenhouse effect was entirely natural until the industrial revolution.  In the last two centuries, the burning of fossil fuels has added a manmade contribution to the greenhouse effect.  It is surprising that the GT paper survived peer review, which is a quality-control policy that makes it harder to publish erroneous papers.  Harder, but evidently not impossible.

  22. @DrTsk
    I didn't say the atmosphere was opaque, Connelly did in a reference pointed to by muoncounter. (-snip-)
    ...the troposphere is largely opaque to infra-red radiation...[http://www.wmconnolley.org.uk/sci/wood_rw.1909.html]
    You can argue whether it is opaque or just largely opaque. But the Box experiment proves it is not totally opaque to IR. And G&T went into a lengthy discussion of the various

    (-snip-). Did you miss the question mark in my sentence? The correct answer was (d). It would certainly make sense that at some altitude H2O doesn't show up.

    I didn't do any experiments that invalidated anything. I'll leave that to G&T.

    @1167 Tom Curtis

    Tom, I have to deal with #4 first. If the term "green house effect" doesn't refer to the process by which green houses, cars and atrium skylights heat their interiors when the sun is shining, but instead refers to the supposed means by which the atmosphere keeps the planet warm, what name do you propose for the means by which green houses are kept warm in sunlight? T&G and the others they quote are absolutely right that this term has no business being used to describe what is going on in the atmosphere. (-snip-)

    I have seen all those curves before and that discussion on heat seeking missiles. The curves certainly don't support Connelly's largely adjective either. While I didn't include the adjective at some point, I did reference the source so it should have been clear what was being discussed. I'll have to apologize for that.

    I didn't see a curve for the incoming radiation from the sun or a computed specific intensity over the UV, visible and IR spectra at the ground. You would need to show that to make some headway with G&T.

    @1166 Chantreau
    A small point, but in a previous post I had stepped out and pointed my IR thermometer at the bottom of rain clouds which I think I mentioned then. I am aware that certain types of clouds like cirrus are comprised of ice crystals, but I was really referring to the clouds that usually pass over my location in which, yes, the temperature is below the dew point, but no, the temperature is not below the freezing point at whatever altitude they are at. Generally that only happens in summer and spring when hail forms. Clouds form when convection lifts warm air from the surface and the lapse rate then lowers the temperature of the moisture in the air to below the dew point.
    Response:

    [DB] Specious, argumentative statements detracting from the dialogue snipped.

  23. @1165 Scandenp
    From Table 8 on page 22.















    BandRangePortion
    [nm][%]
    ultraviolet0 − 38010.0
    visible380 − 76044,8
    infrared 760 − ∞45,2
  24. @1165 Scandenp
    From Table 8 on page 22 G&T come up with 45.2% of the energy arriving from the Sun as infrared. 44.8% is visible light and 10% is UV. It is just a standard calculation shown in equation 30. It is based on the sun radiating as a black body at T=5780K. G&T comment that the fact of this distribution is often overlooked in textbooks.

    He arrives at this by asserting that the Kirchhoff-Planck law is a more appropriate for evaluating sunlight. The Stefan-Boltzmann law is a special case of Kirchoff-Planck.

    So are you taking exception to his calculation of the portion of radiation received by the earth? Is there some alternative to considering the sun a black body radiator that is more correct? Now he is not saying that this is the spectrum you will see at the earth's surface. He also discusses and accounts for absorption at various wavelengths by the atmosphere.

    As far as books by Gerlich:
    (-snip-)
    Response:

    [DB] Off-topic snipped.

  25. TOP,

    First, the purpose of the Wood experiment is not to "determine whether radiation or convection controls the temperature of the air inside the box."

    The purpose is to determine whether or not in a system where convection is not present radiation alone will have the capacity to control temperature in the boxes.

    [This is a common — the most common — design for most experiments, by pinning down all variables except the one to be tested.]

    The experiment fails because it does not accomplish that goal. It does not remove convection from the system to allow only radiation to be a factor. The end result is that one cannot draw any conclusions from the experiment.

    Fortunately, numerous other, valid experiments have been performed, and this is why all educated scientists today understand GHG theory and dismiss things like Wood's experiment and the people who cling to it.

    But I asked you a question that you did not answer (or tried to answer snidely, while in the process failing completely to explain your logic): How can an IR-opaque atmosphere possibly lead to global cooling? What exactly do you think is going to happen?
  26. @1171 muoncounter
    Fluke is a little rich for my budget. But my instrument reads lower than 30C. Is it accurate at that temperature? I don't know, never sent it out. Maybe all I can say is that my instrument reads at the bottom of it's scale. Still mighty cold.

    If you want to know what your IR thermometer sees fabricate a tube that gives a D-S ratio appropriate for your instrument. Then look through it.

    I will reiterate, an IR thermometer doesn't care where the photons come from or how far they travel. If you point it at the clear sky it will see the clear sky. Then it is a matter of it integrating the radiant energy in it's window. If my instrument sees a preponderance of gas at -55F or your Fluke sees a preponderance of gas at -30C it is still far colder than the air in the troposphere intervening.

    And it is very likely that a simple instrument like this sees a fairly narrow radiation band avoiding the CO2 and H2O absorption bands although the fact that it sees clouds suggests that the water band is included in it's range.
  27. "Generally that only happens in summer and spring when hail forms. Clouds form when convection lifts warm air from the surface and the lapse rate then lowers the temperature of the moisture in the air to below the dew point."

    No. Wrong, and wrong again. Lowering the temperature of the moisture? And you comment about "GH effect" being a misnomer? How do you lower the temperature of a characteristic of the air? Please.

    Hail happens when turbulence carries large droplets above the freezing level in cumulonimbus clouds. Above the freezing level, it becomes ice, goes back down where it gathers another layer of liquid water, and up again, where that new layer freezes and so on. In very violent clouds, this cycle can be repeated so many times as to create hailstones the size of a grapefruit, which I personally witnessed in Fort-Worth in 1995. It can also be violent enough to make these stones "pop out" of the cloud and land many miles away, over an area where the storm seems distant enough that you'd be safe, sometimes even on an area overlaid by clear skies.

    If one finds an intact hailstone and slices it, the layers can sometimes be visible.

    Clouds do not happen only when air is lifted up and cools down, they form when air temperature is brought to the dew point, whatever the mechanism, and there are many. Contrails are caused by addition of moisture, saturating air that would otherwise not see the formation of clouds because it is too dry.

    Over the past few nights, where I live there were clear skies and the formation of low altitude clouds, sometimes going all the way to the ground (that's called fog), caused by radiation cooling. These clouds persisted through the rest of the night, and well into the morning; they were composed of water droplets, even though temperature fell below freezing. Cloud formation by addition of moisture is also common over large bodies of water in the fall, when the water remains warm enough to evaporate in cold, dry air. The possible combinations for cloud formations are in fact endless and can be very localized.

    I am not keeping my instrument rating current around here because the MEAs (google it) are high enough to be above freezing during most of the months when IFR conditions prevail. As a result, I would encounter icing (most likely rime ice, you can google that too) throughout all this time and would need an aircraft approved for flight into known icing conditions, and these are usually too expensive for amateur type of operations. These icing conditions happen precisely because clouds formed of liquid water droplets exist at temperatures below freezing.

    Then there is also supercooled water, you can google that too. Quite an interesting phenomenon. Although it is unusual, it does happen and will give you an instant coating totalling several hundred pounds to upward of a ton, depending what you're flying.

    "the fact that it sees clouds suggests that the water band is included in it's range." Isn't the water band for water vapor? Can you share your source for the specific range of IR emission for amospheric liquid water? Isn't it rather that these liquid water clouds only relfect radiation, a totally different process that your instrument can not discriminate?

    Methinks, you're talking about things that you have no true expertise about and that G&T have you fooled with their wordplay, because that's all their paper really is. Whatever.
  28. Oh dear. Sorry DB. Bit of brain fade today.
  29. "You can argue whether it is opaque or just largely opaque. But the Box experiment proves it is not totally opaque to IR."

    Just exactly what is the difference between "not totally" and "largely"? Sorry but that is just poor rethoric,especially from soneone accusing others to put words in his mouth.

    About this: "From Table 8 on page 22 G&T come up with 45.2% of the energy arriving from the Sun as infrared. 44.8% is visible light and 10% is UV."

    No, that's what not what the table says at all. It says that 45.2% of "Sunlight" (from the table's caption) received is within a certain range of wave length, 44.8% in another range and 10% in yet another. Not all wave lengths carry the same amount of energy, so the total amount of energy depends on how much of the spectrum is at what frequency and how much energy that frequency carries.

    Higher frequency photons are more energetic. If we were receiving 50% IR and 50% UV, guess which 50% would carry the most energy? Another indication of your lack of comprehension in these matters.

    By the way, is that repartition in table 8 at the top of atmoshere or at the surface? Do you understand why that matters? Do you know what the repartition is at the surface? If any difference exists, what does the difference tell us?

    I find it suprising that you could interpret G&T's table 8 as a distribution of energy. They don't suggest that themselves, despite their remark that the frequency (wave length) repartition is often overlooked. That remark itself is misleading; what matters in consideration of an atmospheric GH effect is the amount of solar radiation that reaches the surface, of which only a small portion is IR, precisely because of the fact that the atmosphere is largely opaque to IR, so most of the solar IR does not reach the surface.

    Which begs the question: why is there so much IR to be measured by instruments at the surface? Surely there has to be some work done by scientists to study this, don't you think? Have you looked for it? What is out there?

    On another note, the instrument to measure IR radiation is a pyrgeometer, different from an IR thermometer. The only thing you are demonstrating with your measurements is that there is indeed no violation of the 2nd law in the atmosphere. Quite a different thing than measuring how much downwelling IR radiation reaches the surface and what the overall energy balance is across the entire spectrum.

    The question is, when you use your instrument in the way you described, what exactly are you measuring? What physical quantity is represented by these numbers?
    How does that measurement contradict the existence of downwelling IR radiation from the atmosphere to the surface (as measured by a pyrgeometer)?

    Your way of approaching science is very much reminiscent of the people on WUWT who could not understand the phase diagram of CO2 and had to partially recreate the diagram before they could finally grasp that carbonic snow was not going to happen on Earth. The fact that you find in yourself the authority to attempt to pontificate on these subjects is truly srange.

    Nonsense on top of confusion, endless play on words, mangled semantics used as a basis for rethorical argument, it does not get better as time goes by. The more this thread goes on, the more it reveals about D-K effect, rather than atmospheric radiative physics. G&T knew exactly what the public out there is like, so they knew what they were doing and they should be ashamed for doing so much harm. To prove what? That they could play with words? that atmospheric scientists should be more careful with their language?Sheesh.
  30. TOP - I am perfectly capable of reading what G&T said. Are you capable of seeing what is wrong with that statement?
  31. TOP @1172: I retain the numbering of topics from my post 1167:

    Point 1) I refer you to the global energy balance by Trenberth et al, 2009:



    Upward IR radiation from the surface is 390 W/m^2. Upward IR radiation from the surface at the TOA is 40 W/m^2. Ergo, approximately 90% of all IR radiation from the surface is absorbed by the atmosphere. If you had a block of quartz which only let through 10% of the light shone into it, I am sure you would say it was "largely opaque". Why you are so determined to apply a different standard to atmospheres is beyond me.

    Point 2) The incoming solar energy is an irrelevant point. There is clearly less energy being radiated at some bands than at others in the IR spectrum. It follows that in those other bands, they must radiate at a higher intensity than they otherwise would have, and ergo the source of the radiation must be warmer. However, as noted in the diagram above, incoming, unreflected solar radiation is 239 W/m^2.


    Point 4) I am not going to try an reform the linguistic conventions of an entire language just because fake skeptics attempt to use those conventions to deceive people. Furthermore, I have seen how fake skeptics treat those who do try to reform the language. They take claims saying "greenhouse effect" is an inaccurate term and misquote them as claims that there is no greenhouse effect, ie, that the surface is not warmed by the presence of CO2 in the atmosphere.

    Everybody can understand that rubber ducks and tin cans are no longer made out of rubber or tin (respectively) but that the name persists. Everybody (almost) can understand that the ancient Greek theory of the four humours is false, and are not confused by people saying they are in "good humour", or that somebody has a phlegmatic personality. Likewise, everybody willing to think can understand that the warming of the surface by CO2 in the atmosphere is called the "greenhouse effects" due to a historical misunderstanding, but that that is consequently its name. They further understand that people trying to argue against a scientifically demonstrated physical effect based on coincidences of linguistic accident are intent on deceiving.

    Are you in that latter category? And if not, why are you making this an issue?
  32. So we're supposed to be willing to overthrow a well-known scientific principle on the basis of one hotly-disputed paper and a backyard experiment. If valid, from such discoveries come Nobel Prizes.

    The details of that experiment:

    - A measuring device costing less than $82 (current amazon.com price for a Fluke 62).
    - "Is it accurate at that temperature? I don't know, never sent it out."
    - "it is very likely that a simple instrument like this sees a fairly narrow radiation band avoiding the CO2 and H2O absorption bands" -- my IR thermometer has a quoted spectral response of 6.5 to 18 microns, which the figure below shows is not 'narrow band.'



    - the quoted range of such sensors is 6 feet or less -- works fine for checking AC/heating duct air temp.

    But if this is a credible experiment, tickets to Stockholm are in order. However, I wonder why NASA goes to all this trouble and expense designing and calibrating real narrow band (centered around 10.8 and 12 microns) IR sensors for satellites. Why not just put up a few hundred dollars worth of retail models?

    Oh, I forgot, they just do all this to boost their funding. Right.
  33. I'll add to what TC and Muon just said and make one bold statement: the measurements you obtain, considering how your instrument works, are entirely consistent with everything known of atmospheric radiative physics. They do not contradict the GH effect at all. In fact, knowing all the applicable local conditions at the time of measurement, they could be predicted from the physics.

    I'll leave it to you figure out why and how. You write here with the pretention to demonstrate that current understanding of atmospheric radiative physics is deeply flawed, there is then no doubt that you have the abilities to do that work. Then, you can explain exactly where the flaws are in the process used for the prediction.
  34. TOP - I would like to point out that every 'objection' you have raised has been discussed ad nauseum, and shown incorrect, in the previous thousand comments.

    G&T is a horrible paper, incredibly flawed, and the various "2nd Law of Thermodyamics" objections to the radiative greenhouse effect are simply not valid.

    At this point I consider the very fact that someone raises such objections to be a clear indicator that the proponent (a) lacks a sufficient education in physics, and (b) will grab onto anything that might even plausibly provide an objection to the science, regardless of validity. It's not (IMO) a promising sign.

    Please - read the Opening Post (OP), read through the thread a bit, go look at examinations of this topic such as the excellent work at Science of Doom (who has multiple threads on this topic). I think you might find a deeper understanding of this topic worthwhile.
  35. KR:

    Having followed the multiple, lengthy exchanges between TOP and you and other SkS authors, I am firmly convinced that TOP's sole purpose is to litter this comment thread with excerpts from the G&T paper.

    In my opinion, this behavior ought to be against SkS Comment Policy.

    If it were my call, I would ban TOP from posting on SkS and delete all of his comments.
  36. John Hartz @1185, I do not think merely presenting a view, however flawed, should be grounds for banning or deletion of posts. Continuous and repetitive presentation of the same point again and again should be grounds for deletion of further repetitions as of topic, but I do not believe TOP has reached that point, yet.
  37. @1171 Moderator
    I viewed the BBC experiment. Thanks for the notes. Among other problems:
    1. Lights repositioned between 1:14 and 1:18 so that the CO2 light is more direct.
    2. No control over the positioning of the lights.
    3. The left bottle had .04% by volume CO2 while the right bottle probably had 90% by volume CO2 proving that CO2 absorbs more IR than air if the experiment actually represented equal impingement of IR on the bottles. All this would prove is that CO2 absorbs IR which nobody is disputing or perhaps that it takes an almost pure CO2 atmosphere to raise the temperature a few degrees.
    4. The right bottle had an object behind it that may have reflected energy back into the bottle.
    5. There was no control, no Design of Experiment and no statistically relevant reduction of data. This was just a snake oil presentation.

    This experiment simply proves, if anything, that CO2 absorbs IR, it has nothing to do with explaining why greenhouses warm in the sun.

    (-snip-).
    Response:

    [DB] Moderation complaints snipped.

  38. @1186 Tom Curtis
    Thank you Tom. I am trying real hard to make a reasoned point in a tough forum.
  39. TOP@1187
    "There was no control, no Design of Experiment and no statistically relevant reduction of data. This was just a snake oil presentation."

    Are you serious? This was not a graduate thesis, this was a 6th grade level science demonstration. If you really want to *prove* that it is fabricated nonsense perform the experiment yourself. It should not take more than an hour start to finish and you probably have everything you need in our kitchen.
    Please post a youtube link when you are done.
    I eagerly await your results.
  40. @1185 John Hartz

    This is a discussion about G&T. Their paper is long and I saw little specific discussion of the points that they made that could be traced to specific parts of that paper. So I quote it. Frankly I don't think that a lot of the discussion on this whole thread has attempted to address G&T. And even when quoting G&T the discussion seemed to diverge from the topic of the post rather rapidly.

    I will say that I haven't found much of anything in the respondents to my comments here that convince me of the error of G&T's ways. I learn a lot but I see a lot of regurgitation of information found in other papers and books. Most of it just comes down on me for word choice or "rhetoric". Guess I'll have to take remedial English or writing. But then this is a blog and I would expect to be cut some slack on form and style like I cut slack for others.

    And if banning me is the only way to win the argument that speaks loads for the argument.

    G&T have made some headway. In 1184 KR uses the term "radiative greenhouse effect" which to me is acceptable in place of the "convective greenhouse effect" which is what happens in real greenhouses. And I will note that G&T wanted to use the term "atmosphere effect" in place of "greenhouse effect" when talking about warming the atmosphere by radiation.
  41. 1189 pbjamm
    Read my response. I don't have a problem with the science. CO2 does absorb IR. Look at muon's graphs and many others posted here. Those are actual measurements taken with expensive instruments. I do have a problem with calling it proof of the "radiative greenhouse effect" as applied to real greenhouses when real greenhouses don't typically have a 90% CO2 atmosphere. Perhaps that experiment should be called the "absorptive greenhouse effect".

    Mr. Wizard did a much better job of controlling his 6th grade experiments in the '60s.
  42. TOP@1191:
    I do have a problem with calling it proof of the "radiative greenhouse effect" as applied to real greenhouses when real greenhouses don't typically have a 90% CO2 atmosphere
    =======
    Is this a purely semantic argument that 'greenhouse effect' is an inaccurate description? At this point I am not clear what you are arguing for or against.
  43. TOP - as has been said before, great hunks of G&T are telling us what everyone knows full well but possibly they and definitely you, seem to think contradicts how we understand atmospheric physics to work. The skeptic point to take down in their paper was their idea that 2nd law is being violated. It is not.

    Muon has pointed you at the spectral observations from both top and looking up. Both agree with model calculations which could not be valid if G&T were right. There is no observational evidence to contradict the GHE and a very great deal to validate it.

    Now, have you figured out what was wrong with the G&T statement I quoted earlier?
  44. Wow, almost 1200 comments in and we have consensus: It shouldn't be called the greenhouse effect because 'real greenhouses don't work that way.'

    In what way do these pedantics change the physical science involved - or the outcome?

    TOP#1187: Very insightful critiques. Now do the same with your 'I measured the temp of the stratosphere with my handheld IR thermometer experiment.'
  45. @1192 pbjamm
    It isn't semantics. The good BBC professor purported to demonstrate the "radiative greenhouse effect" by comparing temperatures in a) a bottle filled with air (0.04% CO2) and b) a bottle filled with CO2. The experiment did not demonstrate what was purported even a little. Nor did it invalidate Wood's experiment in 1909.

    You have read G&T haven't you? They have a big problem with the term "greenhouse effect", if for no other reason than it is not well defined, at least for a mathematical physicist's purposes and it is not an "effect". There are 14 subsections in their paper that find flaws in published definitions of the term in, I would hope, respected literature on AGW. G&T are arguing the "semantics" because without defining terms, what exactly is being discussed? What I say is of little consequence.

    And just a note of style, if you quote, put it in quotes or indent. As everyone knows, I am easily confused.
  46. TOP - we have no problem with idea that greenhouse effect is badly named. Its just not news. This in no way invalidates the fact the atmospheric greenhouse gases warm the planets. That IS the only point of substance for climate. SoD assumed G&T just skipped 100 years of literature; I think it more likely that they were trying to sow seeds of doubt about GHE with that long preamble. Looks like it worked.

    Are you arguing that IPCC science doesnt understand GHE. (eg as described here). Or that Ramanathan and Coakley 1978 (the basis for current calculations) have got it wrong?
  47. TOP,

    You still have not answered the question "How can an IR-opaque atmosphere possibly lead to global cooling?"

    I only ask again (for the third time) because I think that this may be at the heart of at least some of your problems. If you believe this, then there is something seriously wrong with your understanding of the physics involved.

    Please explain yourself.
  48. @1163, 1193 scadenp
    Well, I thought I did in 1174, but Philippe in 1179 pointed out that I incorrectly used the term energy for "Sunlight". It just all depends on what Blambda means when integrated as in equation 30 on page 22. It could just be power (energy per unit time) integrated over a portion of the spectrum. [I am being a bit imprecise here. You can look up Blambda elsewhere.]

    That table in G&T is referring to the black body radiation of the sun before it passes through the atmosphere. So of course the gases in the atmosphere are going to take their "cut" of the radiant energy on the way down. Wood demonstrated, however, that a significant and measurable portion of IR does in fact reach the ground. But muon's charts support this finding.

    Just out of pure curiosity, how does RGHE deal with the warming of CO2 from the sunlight? And why does muon's graph show such a low temperature in the CO2 notch looking down from above if there is so much radiant energy available to heat it? I have a thought on that but I am wondering what your opinion is.
  49. @1197 Sphaerica
    I think I just answered part of that in 1198. In the Wood (1909) experiment, there was a small discrepancy in how fast the two boxes heated. The box with the IR transparent cover heated faster. So I jumped to the conclusion that if that was so, and if placing an IR opaque filter in front of the box caused the temperature rise to drop, then the same would be true if the atmosphere were IR opaque (which it isn't, see muon's charts.)
  50. I genuinely have no idea what any of this has to do with violations of the 2nd Law of Thermodynamics.

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