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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

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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)

 

At a glance

Although this topic may have a highly technical feel to it, thermodynamics is a big part of all our everyday lives. So while you are reading, do remember that there are glossary entries available for all thinly underlined terms - just hover your mouse cursor over them for the entry to appear.

Thermodynamics is the branch of physics that describes how energy interacts within systems. That interaction determines, for example, how we stay cosy or freeze to death. You wear less clothing in very hot weather and layer-up or add extra blankets to your bed when it's cold because such things control how energy interacts with your own body and therefore your degree of comfort and, in extreme cases, safety.

The human body and its surroundings and energy transfer between them make up one such system with which we are all familiar. But let's go a lot bigger here and think about heat energy and its transfer between the Sun, Earth's land/ocean surfaces, the atmosphere and the cosmos.

Sunshine hits the top of our atmosphere and some of it makes it down to the surface, where it heats up the ground and the oceans alike. These in turn give off heat in the form of invisible but warming infra-red radiation. But you can see the effects of that radiation - think of the heat-shimmer you see over a tarmac road-surface on a hot sunny day.

A proportion of that radiation goes back up through the atmosphere and escapes to space. But another proportion of it is absorbed by greenhouse gas molecules, such as water vapour, carbon dioxide and methane.  Heating up themselves, those molecules then re-emit that heat energy in all directions including downwards. Due to the greenhouse effect, the total loss of that outgoing radiation is avoided and the cooling of Earth's surface is thereby inhibited. Without that extra blanket, Earth's average temperature would be more than thirty degrees Celsius cooler than is currently the case.

That's all in accordance with the laws of Thermodynamics. The First Law of Thermodynamics states that the total energy of an isolated system is constant - while energy can be transformed from one form to another it can be neither created nor destroyed. The Second Law does not state that the only flow of energy is from hot to cold - but instead that the net sum of the energy flows will be from hot to cold. That qualifier term, 'net', is the important one here. The Earth alone is not a "closed system", but is part of a constant, net energy flow from the Sun, to Earth and back out to space. Greenhouse gases simply inhibit part of that net flow, by returning some of the outgoing energy back towards Earth's surface.

The myth that the greenhouse effect is contrary to the second law of thermodynamics is mostly based on a very long 2009 paper by two German scientists (not climate scientists), Gerlich and Tscheuschner (G&T). In its title, the paper claimed to take down the theory that heat being trapped by our atmosphere keeps us warm. That's a huge claim to make – akin to stating there is no gravity.

The G&T paper has been the subject of many detailed rebuttals over the years since its publication. That's because one thing that makes the scientific community sit up and take notice is when something making big claims is published but which is so blatantly incorrect. To fully deal with every mistake contained in the paper, this rebuttal would have to be thousands of words long. A shorter riposte, posted in a discussion on the topic at the Quora website, was as follows: “...I might add that if G&T were correct they used dozens of rambling pages to prove that blankets can’t keep you warm at night."

If the Second Law of Thermodynamics is true - something we can safely assume – then, “blankets can’t keep you warm at night”, must be false. And - as you'll know from your own experiences - that is of course the case!

Please use this form to provide feedback about this new "At a glance" section. Read a more technical version below or dig deeper via the tabs above!


Further details

Among the junk-science themes promoted by climate science deniers is the claim that the explanation for global warming contradicts the second law of thermodynamics. Does it? Of course not (Halpern et al. 2010), but let's explore. Firstly, we need to know how thermal energy transfer works with particular regard to Earth's atmosphere. Then, we need to know what the second law of thermodynamics is, and how it applies to global warming.

Thermal energy is transferred through systems in five main ways: conduction, convection, advection, latent heat and, last but not least, radiation. We'll take them one by one.

Conduction is important in some solids – think of how a cold metal spoon placed in a pot of boiling water can become too hot to touch. In many fluids and gases, conduction is much less important. There are a few exceptions, such as mercury, a metal whose melting point is so low it exists as a liquid above -38 degrees Celsius, making it a handy temperature-marker in thermometers. But air's thermal conductivity is so low we can more or less count it out from this discussion.

Convection

Convection

Figure 1: Severe thunderstorm developing over the Welsh countryside one evening in August 2020. This excellent example of convection had strong enough updraughts to produce hail up to 2.5 cm in diameter. (Source: John Mason)

Hot air rises – that's why hot air balloons work, because warm air is less dense than its colder surroundings, making the artificially heated air in the balloon more buoyant and thereby creating a convective current. The same principle applies in nature: convection is the upward transfer of heat in a fluid or a gas. 

Convection is highly important in Earth's atmosphere and especially in its lower part, where most of our weather goes on. On a nice day, convection may be noticed as birds soar and spiral upwards on thermals, gaining height with the help of that rising warm air-current. On other days, mass-ascent of warm, moist air can result in any type of convective weather from showers to severe thunderstorms with their attendant hazards. In the most extreme examples like supercells, that convective ascent or updraught can reach speeds getting on for a hundred miles per hour. Such powerful convective currents can keep hailstones held high in the storm-cloud for long enough to grow to golfball size or larger.

Advection

Advection is the quasi-horizontal transport of a fluid or gas with its attendant properties. Here are a couple of examples. In the Northern Hemisphere, southerly winds bring mild to warm air from the tropics northwards. During the rapid transition from a cold spell to a warm southerly over Europe in early December 2022, the temperatures over parts of the UK leapt from around -10C to +14C in one weekend, due to warm air advection. Advection can also lead to certain specific phenomena such as sea-fogs – when warm air inland is transported over the surrounding cold seas, causing rapid condensation of water vapour near the air-sea interface.

Advection

Figure 2: Advection fog completely obscures Cardigan Bay, off the west coast of Wales, on an April afternoon in 2015, Air warmed over the land was advected seawards, where its moisture promptly condensed over the much colder sea surface.

Latent heat

Latent heat is the thermal energy released or absorbed during a substance's transition from solid to liquid, liquid to vapour or vice-versa. To fuse, or melt, a solid or to boil a liquid, it is necessary to add thermal energy to a system, whereas when a vapour condenses or a liquid freezes, energy is released. The amount of energy involved varies from one substance to another: to melt iron you need a furnace but with an ice cube you only need to leave it at room-temperature for a while. Such variations from one substance to another are expressed as specific latent heats of fusion or vapourisation, measured in amount of energy (KiloJoules) per kilogram. In the case of Earth's atmosphere, the only substance of major importance with regard to latent heat is water, because at the range of temperatures present, it's the only component that is both abundant and constantly transitioning between solid, liquid and vapour phases.

Radiation

Radiation is the transfer of energy as electromagnetic rays, emitted by any heated surface. Electromagnetic radiation runs from long-wave - radio waves, microwaves, infra-red (IR), through the visible-light spectrum, down to short-wave – ultra-violet (UV), x-rays and gamma-rays. Although you cannot see IR radiation, you can feel it warming you when you sit by a fire. Indeed, the visible part of the spectrum used to be called “luminous heat” and the invisible IR radiation “non-luminous heat”, back in the 1800s when such things were slowly being figured-out.

Sunshine is an example of radiation. Unlike conduction and convection, radiation has the distinction of being able to travel from its source straight through the vacuum of space. Thus, Solar radiation travels through that vacuum for some 150 million kilometres, to reach our planet at a near-constant rate. Some Solar radiation, especially short-wave UV light, is absorbed by our atmosphere. Some is reflected straight back to space by cloud-tops. The rest makes it all the way down to the ground, where it is reflected from lighter surfaces or absorbed by darker ones. That's why black tarmac road surfaces can heat up until they melt on a bright summer's day.

Radiation

Figure 3: Heat haze above a warmed road-surface, Lincoln Way in San Francisco, California. May 2007. Image: Wikimedia Commons.

Energy balance

What has all of the above got to do with global warming? Well, through its radiation-flux, the Sun heats the atmosphere, the surfaces of land and oceans. The surfaces heated by solar radiation in turn emit infrared radiation, some of which can escape directly into space, but some of which is absorbed by the greenhouse gases in the atmosphere, mostly carbon dioxide, water vapour, and methane. Greenhouse gases not only slow down the loss of energy from the surface, but also re-radiate that energy, some of which is directed back down towards the surface, increasing the surface temperature and increasing how much energy is radiated from the surface. Overall, this process leads to a state where the surface is warmer than it would be in the absence of an atmosphere with greenhouse gases. On average, the amount of energy radiated back into space matches the amount of energy being received from the Sun, but there's a slight imbalance that we'll come to.

If this system was severely out of balance either way, the planet would have either frozen or overheated millions of years ago. Instead the planet's climate is (or at least was) stable, broadly speaking. Its temperatures generally stay within bounds that allow life to thrive. It's all about energy balance. Figure 4 shows the numbers.

Energy Budget AR6 WGI Figure 7_2

Figure 4: Schematic representation of the global mean energy budget of the Earth (upper panel), and its equivalent without considerations of cloud effects (lower panel). Numbers indicate best estimates for the magnitudes of the globally averaged energy balance components in W m–2 together with their uncertainty ranges in parentheses (5–95% confidence range), representing climate conditions at the beginning of the 21st century. Figure adapted for IPCC AR6 WG1 Chapter 7, from Wild et al. (2015).

While the flow in and out of our atmosphere from or to space is essentially the same, the atmosphere is inhibiting the cooling of the Earth, storing that energy mostly near its surface. If it were simply a case of sunshine straight in, infra-red straight back out, which would occur if the atmosphere was transparent to infra-red (it isn't) – or indeed if there was no atmosphere, Earth would have a similar temperature-range to the essentially airless Moon. On the Lunar equator, daytime heating can raise the temperature to a searing 120OC, but unimpeded radiative cooling means that at night, it gets down to around -130OC. No atmosphere as such, no greenhouse effect.

Clearly, the concentrations of greenhouse gases determine their energy storage capacity and therefore the greenhouse effect's strength. This is particularly the case for those gases that are non-condensing at atmospheric temperatures. Of those non-condensing gases, carbon dioxide is the most important. Because it only exists as vapour, the main way it is removed is as a weak solution of carbonic acid in rainwater – indeed the old name for carbon dioxide was 'carbonic acid gas'. That means once it's up there, it has a long 'atmospheric residency', meaning it takes a long time to be removed. 

Earth’s temperature can be stable over long periods of time, but to make that possible, incoming energy and outgoing energy have to be exactly the same, in a state of balance known as ‘radiative equilibrium’. That equilibrium can be disturbed by changing the forcing caused by any components of the system. Thus, for example, as the concentration of carbon dioxide has fluctuated over geological time, mostly on gradual time-scales but in some cases abruptly, so has the planet's energy storage capacity. Such fluctuations have in turn determined Earth's climate state, Hothouse or Icehouse – the latter defined as having Polar ice-caps present, of whatever size. Currently, Earth’s energy budget imbalance averages out at just under +1 watt per square metre - that’s global warming. 

That's all in accordance with the laws of Thermodynamics. The First Law of Thermodynamics states that the total energy of an isolated system is constant - while energy can be transformed from one component to another it can be neither created nor destroyed. Self-evidently, the "isolated" part of the law must require that the sun and the cosmos be included. They are both components of the system: without the Sun as the prime energy generator, Earth would be frozen and lifeless; with the Sun but without Earth's emitted energy dispersing out into space, the planet would cook, Just thinking about Earth's surface and atmosphere in isolation is to ignore two of this system's most important components.

The Second Law of Thermodynamics does not state that the only flow of energy is from hot to cold - but instead that the net sum of the energy flows will be from hot to cold. To reiterate, the qualifier term, 'net', is the important one here. In the case of the Earth-Sun system, it is again necessary to consider all of the components and their interactions: the sunshine, the warmed surface giving off IR radiation into the cooler atmosphere, the greenhouse gases re-emitting that radiation in all directions and finally the radiation emitted from the top of our atmosphere, to disperse out into the cold depths of space. That energy is not destroyed – it just disperses in all directions into the cold vastness out there. Some of it even heads towards the Sun too - since infra-red radiation has no way of determining that it is heading towards a much hotter body than the Earth,

Earth’s energy budget makes sure that all portions of the system are accounted for and this is routinely done in climate models. No violations exist. Greenhouse gases return some of the energy back towards Earth's surface but the net flow is still out into space. John Tyndall, in a lecture to the Royal Institution in 1859, recognised this. He said:

Tyndall 1859

As long as carbon emissions continue to rise, so will that planetary energy imbalance. Therefore, the only way to take the situation back towards stability is to reduce those emissions.


Update June 2023:

For additional links to relevant blog posts, please look at the "Further Reading" box, below.

Last updated on 29 June 2023 by John Mason. View Archives

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Comments 1151 to 1175 out of 1393:

  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?

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