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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 901 to 925 out of 1008:

  1. Re #894 KR you wrote:- "damorbel - Are you asserting that an individual photon (with a particular energy) can be used to identify the temperature of the object that emitted it, thus affecting it's absorption? " Yes I am, that is the basis of all quantum interactions. Since 'an object' can be an individual particle, I don't see the diffiiculty. Further you wrote:- "Or that the possibility of absorption is not a function of photon energy and absorption spectra? If so, you are sadly mistaken." Does this mean that photon interactions do not need to be quantised? Well I don't accept that photon interactions can occur in a non quantised way; throughout the whole electromagnetic spectrum photon interactions with massive particles are always quantised; both on the macroscopic level (many particles described statistically) and at the individual particle level. NB Photons do not interaction with each other.
  2. darmorbel @897 Wein's displacement law, and the spectrum you allude to apply only to black bodies. Gases (such as CO2 and H2O) are not black bodies. The photons they emit will correspond to some of the frequencies of a black body, but their distribution of intensities will not. It is therefore not appropriate to talk of "temperatures" of photons. The energy of a photon is only related to the quantum states involved in the decay when that photon is emitted. Black bodies are "black" because they have a wide range of quantum states, merging into a continuous band. Otherwise they wouldn't be "black".
  3. Darmorbel @901 "damorbel - Are you asserting that an individual photon (with a particular energy) can be used to identify the temperature of the object that emitted it, thus affecting it's absorption? " Yes I am, that is the basis of all quantum interactions. This is incorrect. A molecule of CO2 (for example) has 4 (one doubly degenerate) vibrational modes. These occur at 2565 cm-1 1480 cm-1 and 526 cm-1 If a molecule is in the 1st level excited bend state it can emit a photon at 526 cm-1 But this reveals nothing about how many molecules are in excited states in the other vibrations or rotational excited states or the translational energy that the molecules have.
  4. damorbel - You have completely misread my question; I have to wonder if it's deliberate. You have two complete strawman arguments misstating what I asked. I asked about a photon and "...the temperature of the object that emitted it...". You replied regarding an individual particle, not an object temperature, strawman. An individual photon does not give the temperature of an emitting object. It doesn't even give the temperature of a single molecule, as there are multiple possible emitting down-transitions in electron orbitals for an excited molecule; it doesn't have to drop to ground state. Your answer is incorrect! "Does this mean that photon interactions do not need to be quantised?" - All photon interactions are quantum interactions, I never stated otherwise, strawman. The issue is whether photons emitted by a cooler object can be absorbed by a warmer object (ensemble temperatures), namely the atmosphere and the surface. Since an individual photon does not indicate it's emitting objects temperature, it's absorption depends only upon the absorptivity of the warmer object (determined by quantum interactions, which are off-topic) and the individual photon energies. You are really reaching here.
  5. Re #898 KR you wrote:- "Actually, the peak of the curve is the mode, not the average; the two are not identical unless the distribution is symmetric. That's a fairly common error. " This is a better explanation of mode The relation of temperature to the peak is, once more, a critical one in quantum theory.
  6. I referred to the Statistical Mode, not emitting, molecular, orbital, or other modes. Mistaking statistical mode for mean (average), or vice versa, is a common error. The rest of your post is rather irrelevant to the discussion.
  7. Re #904 KR you wrote:- "I asked about a photon and "...the temperature of the object that emitted it...". You replied regarding an individual particle, not an object temperature, strawman." I asked you to define 'an object'. Until you do, I don't know what you are talking about. So pleeaaase - do it now! For example you wrote:- "as there are multiple possible emitting down-transitions in electron orbitals for an excited molecule; it doesn't have to drop to ground state." Yes and these transitions can be (almost) anywhere in the EM spectrum where many other kinds of interactions can take place; but please let us stick to thermal matters, i.e. interactions that affect temperature.
    Response: [muoncounter] Pedantic requests, such as the definition of 'an object,' are exactly what have put this thread at over 900 comments, many mere attempt at distraction. If you have difficulty with definitions of everyday language, how can your definitions of scientific terminology be taken seriously?
  8. When the fish is in the boat, it may tend to flop and wiggle violently, desperate to once again command the murky, muddy waters in which it has evolved to thrive.
  9. damorbel - "I asked you to define 'an object'." I cannot find such a request from you. But I'll answer it now that you have asked. I am speaking of relevant objects to the radiative greenhouse effect - the surface of the Earth, and the atmosphere. Both are large, ensemble objects, containing temperatures defined by thermal distributions, with thermal emission and absorption spectra defined by their component molecules. You cannot determine the temperature of such an object from a single photon. Single photons have a single energy, a single wavelength. Absorption likelyhood, the real question at hand, is based upon absorption spectra and individual photon energies. So I will ask again: Are you asserting that the possibility of absorption of a photon is not a function of that photon's energy and the potentially absorbing object's absorptivity spectra? DSL - rotfl.
    Response: [muoncounter] Oddly enough, damorbel used to agree:

    We are all familiar with the Planck spectrum, the amplitude of which is a function of the temperature, But taking one photon (with energy a function of frequency), or even one spectral component, does not represent the entire spectrum thus the temperature is not defined. Although a single photon has energy it does not have a temperature.

    See comment#70, this very thread.

    One could only describe this behavior as 'doublethink.'

  10. damorbel, you seem insistent that the following 'fact' is of great import: - the energy of a photon can tell you the 'temperature' of the particle that emitted it Firstly, a single particle doesn't have a temperature, which is a statistical measure. It has an energy. This seems to have been explained to you before. However we are discussing gases, liquids and solids that, as has been explained, emit photons with a range of energies. These spectra are clearly the applicable measures when discussing radiative energy transfer. Next, from what people have said, it seems you believe that a photon emitted by a cooler object cannot be absorbed by a warmer object. Is this an accurate description of your stance?
  11. damorbel, "What % of the heat tranferred to the atmosphere from the ground by radiation:- 14%?......40%?.......90%?" "That is the question I asked you. But I will accept evaporation and convection as 'kinetic'." I'm not sure what you're getting at here or why this matters, but I'll give it a stab. If over 90% of the thermal mass of the planet is in the oceans and about 5% is in the land mass, that leaves maybe a percent or two in the atmosphere? Are you looking for an actual number? Again though, all the kinetic energy flows from the surface to the atmosphere and back to the surface, relative to the radiative budget, are zero. They have to be because all the energy leaving at the top of the atmosphere is radiative. Also, I haven't read this entire thread, but I'm not sure I understand you're fundamental objection here. I don't see how the greenhouse effect violates the second law because it's not about energy going from cold to hot in conduction process. Are you claiming that a photon cannot travel from the colder atmosphere toward the warmer surface?
  12. Damorbel if you keep digging at that rate, you will soon find yourself in molten iron. Wein's law says nothing like what you imply. It says what is the most likely frequency of photons emitted by a source according to the temperature of that source, provided it is a blackbody. If there are several sources emitting at the same time with overlapping spectra, all it tells you is how likely it is that one frequency originated with a source rather than another. If I'm in a room with some light coming from outside (i.e. from the sun) where a light bulb is on, Wein's law can not allow me to determine what was the source of a given photon. Only the relative probability. To go back to the origin of this discussion, it must be made clear that a photon coming from the sun at a given frequency and one coming fron the light bulb at the same frequency will have the same energy. Exactly the same. You previously argued that it was not the case. Wein's law does not allow you to defend that either. Photons do not carry ID cards, no matter how badly your confused mind wants it. The energy of a photon depends only on its frequency. There is no way to tell where an individual photon originated only by examining its frequency. You could say where it could not have originated, that's all. I must say that throwing the photoelectric effect in the mix was yet one of your funniest moves in that strange display of yours.
  13. muoncounter at 909. I disagree. It can also be just double talk, or talk adapted to the need of the moment when conducting an argument with no other function than sowing confusion. Or could it simply be that Damorbel's own confusion is so thorough by now that he is completely lost in the whole thing?
    Response: [muoncounter] Doublethink includes the ability "to forget any fact that has become inconvenient, and then, when it becomes necessary again, to draw it back from oblivion for just so long as it is needed."
  14. 884 KR " The "2nd law" objection to the greenhouse effect is based upon a mistaken notion.." I don't disagree with you. However I'd like to suggest there is another problem. In the post, the statement of the 2nd law has missed out the phrase: "whose sole result". This is a statement that the 2nd law only applies to a closed system. For practical purposes, the system which consists of: the sun, outer space, the solid earth and the earths atmosphere is not a closed system. Outer space is, for practical purposes, an infinite sink. The sun is, again for practical purposes, an infinite source of energy. No one can deny that energy from the sun reaches the surface of the earth - at least, nor that radiated energy which isn't reabsorbed somewhere leaves the system... This is implicit in the text - body heat is in effect a source of energy external to the heat exchange system which is moderated with blankets. So long as some source continues to pump out energy irrespective of the destination of that energy, we're free to build an engine which uses that energy to, for example, concentrate it up to any temperature we can manage. How that engine works (photons, gases, cogs, whatever) is immaterial - the beauty of things like the statistical and termodynmaies is that they are defined for an abstract engine, which applies to all real engines...
  15. damorbel - I think you've been called out; "By thine own words shalt thou be condemned." To wit: "We are all familiar with the Planck spectrum, the amplitude of which is a function of the temperature, But taking one photon (with energy a function of frequency), or even one spectral component, does not represent the entire spectrum thus the temperature is not defined. Although a single photon has energy it does not have a temperature." - damorbel @70, this thread, 24/11/10 (thanks for pointing this out, muoncounter) versus: "But there is no need to have a certain number of particles to make a sample, so one particle with the same energy as the average energy of all the particles also has the same temperature as the whole sample." - damorbel @892, this thread, 31/3/11 Reductio ad absurdum - by contradiction you have disproven your own arguments. You are a troll - willing to say anything, even contradict yourself, in order to prolong an argument. Nothing you have written can be taken seriously, as you are not engaged in a scientific discussion. I have no idea as to your motivations. Perhaps you just like to argue - in that case I consider you a ( -snip- ). Perhaps you are arguing points you don't believe in for ideological reasons - in that case I consider you an ( -snip- ). Or perhaps you do this because it's your job? I'm familiar with that last case; my brother spent years as a denialist of second hand smoke dangers for a major tobacco company. In that case I would ask you the question I asked him - "How much does a soul go for these days?" Overall, I'm disgusted. Everyone - I would encourage you to consider this demonstrated behavior when evaluating anything that damorbel writes, whether here, or on his multiple attempts to redefine the Wiki page on thermodynamics.
    Response: [DB] I completely agree with you, word for word, but I have a role to fulfill. Sorry for the snips.
  16. A bit of summary here, then. I'll put it in the form of a proof for clarity. - Individual photons have energies, but these do not represent the temperatures of the objects that emitted them. You can say what objects could not have emitted that photon based on temperature, but not which one has. - Absorption of a photon by an object (warmer or colder than the emitting object) has a likelyhood based upon the absorption spectra and the energy of the individual photon; not the temperature of the emitting object. - The Earth's surface has an emissivity and absorptivity of ~0.98 in the IR spectra, so 98% of those photons impinging will be absorbed. - 98% of surface impinging atmospheric thermal radiation (aka "backradiation") will be absorbed by the Earth, as per the Earth absorptivity and atmospheric emissivity spectras. - Each photon absorbed, by the first law of thermodynamics, adds to the internal energy and hence temperature of the absorbing object. - The emitting mass of the atmosphere (due to the lapse rate) is colder than the Earth's surface. - Hence a colder object raises the temperature of a warmer object by it's presence. - Therefore: The assertion by Gerlich and Tscheuschner that a cooler object heating a warmer object violates the 2nd law of thermodynamics is categorically false. Q.E.D - Quod erat demonstrandum. --- I don't think that I need to say anything more on this topic. Adieu.
  17. DB - I understand the moderation role, not a problem. I would encourage everyone to form their own opinions of each poster's contributions in light of their content, and act accordingly.
  18. I would, KR, but if the light is coming from a cooler object, I won't be able to see the contribution.
  19. Perhaps, then, DSL, 'the cool shall rule' by virtue of superior vision?
  20. DSL and KR @ 918, 919. ROFL Thus the troll is reduced to its initial insignificance. Reality and the reality-based have prevailed. Yeah!
  21. Re #900 KR You wrote: "and that this absorption (by the 1st law of thermodynamics, conservation of energy) affects and slows the total, net energy transfer to the atmosphere and hence to space." You write about the 1st Law and radiation as if these were the only two energy processes involved - you take into account radiation only. But for a thermodynamic analysis you must include all forms of energy involved in the whole thermodynamic system that comprises the atmosphere. By confining your consideration to radiation only you may well get the answer you are seeking but that is hardly science! As I have mentioned before, you must also account for the gravitational energy of the gas that makes up the atmosphere; it is, after all, the gravitaional component that gives the troposphere its temperature profile (lapse rate) of -6.5K/km. Any attempt to may an 'energy balance' that doesn't include gravitational energy is not going to give an accurate picture.
  22. damorbel - I'm quite surprised to see you back. Have you read my posting here? Evaporation, convection, and the adiabatic lapse rate have all been covered in tedious detail on this thread; if you're interested, look it up. But (personal opinion) I do not consider it worthwhile to debate with someone who (like you) is willing to contradict your own posts in order to prolong an argument - that is trolling, not science.
    Response: While these topics have indirect relevance to the 2nd law and its relationship to the GHE, this thread is not intended as a substitute for a college level physics course. As you pointed out, these topics have already been covered here in excruciating detail. Future off-topic or repetitive comments will be deleted.
  23. Damorbel, you didn't need anyone's help to cover yourself with ridicule. It is glaringly obvious that, not only you haven't the fuzziest idea about these matters, but you are willing to contradict yourself for the sake of argument. This is rather amusing: in the instance noted above, you later adopted an incorrect position, opposite to your originally stated one, which was correct. And you defended the latter with all your rethorical might. Really, that is comical. Cut your losses.
  24. KR When investigating complicated system it's important to approach the mechanism front-wise and linearly. Starting at the start (solar input) avoids confusion as introduction of secondary input/variables (forcing) manifest. If in fact, all the tenets of GHG theory are valid then such a stepwise approach will only hone their formulation. Let's start with what we undoubtedly agree: (e1)emissivity + reflectivity =1 earth's albedo =.3 (e2)emissivity = absorbed energy/ incident energy---or stated continuously--- emissivity = absorbed power/ incident power (e3) σTe4= S/4 * (1-A) flux density emitted via blackbody earth = flux density absorbed via blackbody earth (note to muoncounter, blackbody equivalent) So σTe4= 240 W/m2, represents the theoretical maximum power emitted and adsorbed, via SW, by the surface. This theoretical max flux can be used to calculate actual max flux absorbed by earths surface. Intuitively it make sense, a surface must absorb energy before radiating said energy. So properly, this must be calculated prior to surface to atmosphere emissivity consideration. Also, immediately jumping to actual surface temp and backing out flux, will as said earlier lead to erroneous conclusions. (e4) Because 240 W/m2 is max blackbody absorption it is equal to max incident power. (e5) Earths ε = .98. Using (e2) earths actual absorbed power =.98 * incident power = .98*240 W/ m2 = 235 W/ m2 (e6)Because 235 W/ m2 represents the true absorbed SW radiation value it also represents earth's maximum gray body emissions due to SW. (e7) When surface LW emission flux is equal to SW solar absorption the earth's system is in equilibrium; 235 W/ m2 equates to 254K. Because the 1st law must be upheld this represents the temp maximum via solar radiation. Any additional temperature increase must come from non-radiative energy input. I suspect you are screaming "What about forcing". Ok, by adding radiative reflection/re-radiation flux to solar input, with white, black and gray atmosphere emissivities, LW forcing is easily evaluated. The following section (e8),(e9), (e10), demonstrates GHG physics. Specifically, by adding flux regardless of quantitative magnitude and/or vector magnitude. (e8) Atmosphere ε=0 Teq=time to equilibrium (e7) (235 W/m2) White Note: As Time approaches 2Teqthe Surface flux approaches infinity. Also, as Time approaches 2Teq the atmosphere becomes transparent to visible surface emission...when visible emissions = 240 W/m2 TOA equilibrium is at hand. According blackbody emissions this equates to ~1200K. (e9) Atmosphere ε=1 Teq=time to equilibrium as defined by (e8) Blackbody
    Note: As time approaches 4Teqthe Surface flux approaches infinity. Also, at 3Teq the atmosphere radiates 235 W/m2 plus the 5 W/m2 originally reflected by the surface (e5) give the required 240 W/m2 TOA...302K. (e10) Because(e8) confers the maximum temperature (~1200 K) for TOA equilibrium and (e9) confers the minimum temperature (302K)for TOA, radiative forcing is shown to be a false mechanism. That is, since actual temperature (288 K) is well below the minimum temperature established by blackbody atmosphere, ε < 1, will generate a temperature higher then 302K. (e11) If gray body ε=.612 then, according to (e1), gray body reflectivity = .388 (e12) If gray body ε=.612 then, according to (e2), gray body absorbed = incident flux* ε. (e13) Atmosphere ε=.612 Teq=time to equilibrium as defined by (e8) Gray Note: TOA is achieved when surface radiates 768 W/m2...341K. (e14)As demonstrated, a body's emission can not be increased by it's own reflection,re-radiation, or insulation. As demonstrate lower energy does not increase higher energy, low light does not make more luminous a brighter surface. As demonstrated atmospheric forcing, GHG physics is a false mechanism which in fact violates the 2nd Law. Choosing to ignore this fundamental law leads to fallacious results. Fallacious result such as 341K with an atmosphere emissivity of .612. But just as fallacious misapplication of physics which leads to ε=.612 equating to 288K. Notice I did not say atmospheric radiation does not exist...I did not say the downward radiation does not exist. Atmospheric radiation is isotropic however, lower energy atmospheric radiation can not increase the higher energy surface. Solar input, assuming .3 albedo, can only account for 240 W/m2 flux and therefore delta T between solar input and actual temperature must be a result of non-radiative input.
  25. 924 L.J. Ryan. Nice embedded link to the lecture notes of some Professor Jin-Yi Yu - who has some other nice explanatory material for those finding this all a bit hard. http://www.ess.uci.edu/~yu/ess55.html Where did the rest of the material come from (it is only polite to reference sources, after all)?

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