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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 801 to 825 out of 895:

  1. To moderator: OK, the trolling has indeed gone on long enough. Sorry for adding to it.
  2. LJR #793: So now you are disavowing your own prior arguments? Or wasn't it you who wrote; #715: "Low temperature, (lower energy) atmosphere adding radiative heat to the warmer surface is a violation of the 2nd law." #758: "See this process (unlike the magic box) abides the 2nd law, Hot to Cold." #765: "So regardless of re-radiation and reflection, the atmosphere can NOT warm the warmer Earth...Period." You have said all these things. Right there in the thread history. Yet now you deny it to avoid answering my challenge; "LJ Ryan, I note that you continue to make nonsense claims about greenhouse gases being unable to redirect energy from a colder area to a warmer one while refusing to answer how a parabolic mirror does so." How does the observed reality that EM radiation travels from the surface of a parabolic mirror to the hotter object at the mirror's focal point not disprove your various statements quoted above?
  3. Re 786 Tom Curtis,point by point 1/ Yes 2/Not relevant. - The spectrum of samples plays no part in heat balsnce (Gustav Kirchhoff 1862 'Ueber das Verhälteniß zwischen dem Emissionensvermögen der Körper für Wärme und Licht'. 3/"If a photon is absorbed by a surface, the surface gains the energy that was contained in the photon (by conservation of energy)". - This would only be true if the surface were at 0K i.e. it is not itself radiating. 4/"If energy is absorbed by a surface, all else being equal, the temperature of the surface will rise, and the surface is warmed. - See 3 above. 5/"However, the surface of the Earth is typically warmer than the atmosphere, so it itself is radiating energy to the atmosphere, and is radiating more energy than it receives from the atmosphere." - Very far from clear. Two surfaces close to each other can both be radiating very strongly but without energy transfer. Energy is only transferred if there is some difference in temperature. 6/"Therefore, absent any other energy sources, the net effect of the interchange of photons between atmosphere and surface is that the surface cools and the atmosphere warms." - Yes. (But see 5/) 7/" However, if the atmosphere was not there, or did not radiate IR radiation: (a) the total energy emitted by the surface would still be the same, because that energy is solely a function of its temperature and emissivity; but (b) the surface would receive less energy because it would not be absorbing photons emitted by the atmosphere." - Regards (a)'Energy' is not emitted (see the answer at 5/) - Regards (b)The surface does not get energy from the atmosphere.(see 5/.) 8/"Therefore, over a given period of time, and ignoring all other energy sources, the Earth will cool quicker without an atmosphere containing GHG than it will with one." - This is very different. Now you are talking about 'The Rate of Cooling (Heating). The question of cooling (heating) rate is entirely a function of the albedo (if you take the 'rate' as a % of the temperature). The rate of temperature change (by radiation only) of any body is strongly dependent on its reflectivity, whether it has an atmosphere or not. If a body has a highly reflective surface it means there is very little material to either emit or absorb radiation, so heat transfer is minimal. 9/ -----> end. - No comment.
  4. L.J. Ryan - "Do you agree?" No. The theoretic black body work (including Kirchoff) is based upon a "white light" excitation, equal across all frequencies, absorption and emission by the black body based upon the absorption/emission spectra. The climate, on the other hand, is driven by a band-limited solar input which does not match the thermal emissive spectra, is not greatly affected by greenhouse gases, and hence represents a fixed input, not a match to the thermal spectra at all. And, as I stated earlier, given a fixed input power, and a need to radiate that (or change internal energy and hence temperature), emissivity and temperature have an inverse relationship. As effective emissivity of the planet goes down, temperature goes up. Asserting that the Earth follows "white light" illumination with interdependent absorption/emission is a complete mistake. It's a fixed input power outside the GHG affected thermal spectra, which is sufficient to radiate the incoming 240 W/m^2. And the black body temperature required to radiate that power is a lower limit on the temperature of a gray body of lesser emissivity.
  5. damorbel Please clarify the point you made here: "If a photon is absorbed by a surface, the surface gains the energy that was contained in the photon (by conservation of energy)". - This would only be true if the surface were at 0K i.e. it is not itself radiating." The question does not ask whether the energy absorption is balanced out by emissions, just whether an absorbed photon leads to an energy gain. Are you saying that it does not for an object above 0K? If not, what happens to the energy of the photon? Where did it go? As for how the energy is emitted, keep in mind the Stefan-Boltzman Law. The amount of energy radiated is dependent on the temperature of the material, not whether it has absorbed an extra photon recently. That means if the surface is constantly emitting and absorbing photons, and we increase the number of photons being absorbed, the only way for the surface to emit that extra energy is to get warmer. Do you agree with this? If not, what happens to the energy? How can the extra energy be emitted without the object getting warmer (again keeping in mind Stefan-Boltzmann)? If it isn't emitted, and it doesn't raise the temperature, what happens to this energy?
  6. e, damorbel is consistently and repeatedly avoiding the question as to whether he will even philosophically accept the idea of an experiment as the way to settle a question. (asked here. This to me implies someone only interested in arguing with no intent to resolve anything, perhaps even a paid troll; or someone who prefers a faith-based position. I suggest there is no point discussing with him at all.
  7. Philippe Chantreau 797 "I am talking about a spherical blackbody receiving solar radiation at a constant rate in w/sq m, in the solar spectrum. If, by any means, that blackbody's ability to radiate energy out is impaired, what will happen to its temperature?" As long as the emissivity remains constant, i.e. remains a blackbody, the temperature remains unchanged. Got it Philippe. The spherical blackbody temperature will remain the same.
  8. LJR: "As long as the emissivity remains constant, i.e. remains a blackbody, the temperature remains unchanged." So let's stop talking about theoreticals; what happens when the emissivity of a real planet decreases? By your statement, if solar input remains the same and emissivity decreases, temperature must increase. Or do you now wish to change that as well?
  9. muoncounter 799 "Now that's a radical change of heart, as you specifically described earth's blackbody temperature here. And you've totally ignored the complete defenestration of your argument by KR (#773-775) and CBD (#785)." If you did not understand the context, sorry. Earth blackbody temperature, is a generally (I think) accepted naming convention for earths blackbody temperature equivalent.
  10. muoncounter 808 "So let's stop talking about theoreticals; what happens when the emissivity of a real planet decreases?" If emissivity decreases, the "real planet" will absorb less solar flux. "By your statement, if solar input remains the same and emissivity decreases, temperature must increase." Input would not remain the same (see above). Lower input results in a lower temp. NOT an increase.
  11. L.J. Ryan - "If emissivity decreases, the "real planet" will absorb less solar flux. " Incorrect - please read my post here, and recognize that input power is not affected by the greenhouse gases and their resulting IR emissivity. You have so far ignored my post. The real world climate receives band-limited solar energy unaffected by IR emissivity, hence a fixed input power. Output power (which must, at dynamic equilibrium, match input power) is determined by IR emissivity and the dependent variable, temperature. Please respond or acknowledge.
  12. KR 811 Without addressing the specifics of your post 804, which I will get later this evening or tomorrow, muoncounter 808 made no reference "IR emissivity". Therefore, I stand by 810.
    Response: [muoncounter] Note the use of the words 'real planet;' this is specifically about solar input and how a planet with a greenhouse atmosphere responds. Don't bother replying if you are going to haggle over this nonsense; especially since you claim the right to define 'blackbody' however it suits you.
  13. DSL 800 "Do I have this right?" I'm not sure I understand your entire concept. "But, of course, all atmospheric layers do radiate, and some of this radiation is absorbed by warmer surfaces and warmer atmospheric layers."---To what end. The warmer layers/surface does not get warmer do to this absorption. "Here's the key, though: the current temperature of any atmospheric layer or material within the system is that specific temperature because the atmosphere is already adding its radiated energy. The system is dynamic. if we take away the atmosphere, the surface eventually (quickly) reaches a lower equilibrium temperature. "---Again, I'm not sure I understand...but the lower temperature atmosphere can not increase the temp. of warmer surface. I don't agree with core of your last paragraph. Lower temp IR can not increase the temp. of a warmer surface.
  14. CBDunkerson 802 "LJ Ryan, I note that you continue to make nonsense claims about greenhouse gases being unable to redirect energy from a colder area to a warmer one while refusing to answer how a parabolic mirror does so." NONE of the listed post in 802 do I say "unable to redirect energy from a colder area to a warmer". What I do say: lower temp IR can not increase the temp of a warmer surface. You said: "How does the observed reality that EM radiation travels from the surface of a parabolic mirror to the hotter object at the mirror's focal point not disprove your various statements quoted above?" EM Radiation is reflected, not absorbed and re-radiated, therefore the dish temp is irrelevant.
  15. Re 805 e you write:- "The question does not ask whether the energy absorption is balanced out by emissions, just whether an absorbed photon leads to an energy gain." It takes time, I agree not very much, to absorb a photon, in this time only a body at 0K will not emit a photon. Perhaps it seems trivial to consider individual photons, infinitesimal time periods etc., these are normally handled at macro level by statistics but the bottom line is what happens at the individual photon, particle etc. You wrote further:- "As for how the energy is emitted, keep in mind the Stefan-Boltzman Law. The amount of energy radiated is dependent on the temperature of the material, not whether it has absorbed an extra photon recently" The S-B law is about power (W/m^2) not energy; the energy absorbed can only be found by integrating the power WRT time, during which a body above 0K is also emitting (power) according to S-B law. The equilibrium temperature is where the emitted power equals the absorbed power. It is worth noting that the equilibrium temperature requires only a power balance. A black body is the most efficient emitter but if the body is not black e.g. coloured, a gas or with a refractive index >1 etc., then its emissivity is less than 1. and will not emit so much power at a given temperature; conversley if the emissivity <1 a body will be hotter than a black body, this is why it is a great mistake to assume the Earth 'radiates like a black body'.
  16. LJR #814: So, your latest nonsensical dodge is that EM radiation behaves differently if it has been absorbed and re-emitted than if it 'travels directly' and/or is reflected? Ignoring the ridiculousness of that claim for the moment; How does the EMR emitted by a remote control travel from the couch to the warmer receiver in the heat generating electronic equipment it controls? How does the EMR emitted by a microwave oven travel from the cold walls of the oven to the warmer food being cooked? How does the EMR carrying radio and television broadcasts travel from the transmitter to warmer locations around it - rather than radio and television being routinely interrupted by minor local temperature variations? Heck, how does the EMR of 'sunlight' travel from the cold of space to the warmer upper atmosphere to the warmer still lower atmosphere? By your claims we should all live in perpetual darkness because sunlight cannot approach the warmer surface of the Earth. The 2nd law of thermodynamics does not say that energy can not flow from cold to hot (regardless of whether it has been absorbed and re-emitted somewhere along the way). That is a ridiculous lie which violates thousands of observations from everyday life. What the 2nd law of thermodynamics actually says (in this context) is that the net flow of energy between objects in a closed system will always be from cold to hot... that is, energy flows from the cold objects to the hot ones and vice versa, but since the hot objects are giving off more energy than they receive the net flow is from hot to cold. BTW, your version of events violates the 1st law of thermodynamics... energy can neither be created nor destroyed. You argue that 'colder EM radiation' (setting aside that radiation has no temperature) cannot raise the temperature of a warmer surface... so what happens to it? You've got energy hitting a surface and not making if warmer. It simply ceases to exist. Violating the first law of thermodynamics.
  17. Re #784 Re:- "Response: [muoncounter] We've heard the one about textbooks before. No need recycling your old ideas when they didn't work first time around" I have never raised the matter of text books, it would not occur to me to do so. It has been raised multiple times by other contributors and they received no warning about it I have responded about the reliability of text books. Are there matters to which I may not respond? I do appreciate the work done by mods.
    Response: [muoncounter] Perhaps you should have checked the link in my response to #784. Unless you are a different damorbel, you gave us the parable of your disdain for textbooks some months ago. Do try to keep track of your own words; they are there for all to see.
  18. Following damorbel's logic @815, I can never pay of my debt to the bank. After all, it takes time to complete a transaction, and during the time, the Bank will make many transactions in which they credit other accounts. Therefore, if I make a payment on the debt, they will never have received it, for in the time it takes for them to receive it, a larger amount will have been paid out by them. Therefore, they should be under no obligation to credit my account with the amount paid. If that sounds like casuistry, it is only because the argument mirrors damorbel's. Transparently for those not inclined to casuistry, if in damorbel's book keeping, the energy of the incoming photon is immediately credited to the outgoing radiation, then the amount of energy lost by the absorbing body is reduced by the amount of energy gained from incoming photons. Because less energy is lost, the body will therefore have more energy (and hence be warmer) than an equivalent body that started at the same temperature and emissivity but did not have the incoming radiation. In fact, damorbel is really trying to run two sets of books here, and hoping that we do not notice. In one set of books he credits the incoming energy to the simultaneous outgoing radiation so that he does not have to account for the absorbed energy in discussing the temperature change of the absorbing body. In the second set of books he debits all outgoing energy from the emitting body. Only by keeping both books separate can he pretend that a cool body interacting with a warm body can change the equilibrium temperature, ie, the temperature at which incoming energy matches outgoing energy, for that warm body.
  19. Re #785 CBD you wrote:- "LJ Ryan, I note that you continue to make nonsense claims about greenhouse gases being unable to redirect energy from a colder area to a warmer one while refusing to answer how a parabolic mirror does so." The absorption of radiation and re-emitting is not what is meant by 'redirect(ion)'. Redirection is what a mirror does, it does not change the wavelength (colour) of the (redirected) radiation; the energy is not absorbed by a mirror (or any other reflective process e.g. scattering, as with fog.) thus the temperature of the mirror is not changed. The converse is also true, the redirection of light by a mirror is, at first order, independent of the temperature of the mirror - a hot mirror works much the same as a cold one.
  20. Re #804 CBD you wrote:- "The theoretic black body work (including Kirchoff) is based upon a "white light" excitation, equal across all frequencies, absorption and emission by the black body based upon the absorption/emission spectra." Arguing Kirchhoff's contribution was confined to 'black bodies' is not correct. Kirchhoff was the first to consider 'arbitrary' bodies, ones that reflect, refract, are (partially) transparent etc., e.g. mirrors, coloured bodies, gases etc., thus all radiation, including that with a narrow spectral range. Subsequent developments in atomic and quantum theory have not invalidated his work, which would have been rather unlikely because his work was the inspiration for it!
  21. Re #816 CBDunkerson you wrote:- 1/"How does the EMR emitted by a remote control travel from the couch to the warmer receiver in the heat generating electronic equipment it controls?" - Remote controls emit high brightness narrow band IR that is focussed; the detector at the receiver can distinguish the RC bright spot against yhe background radiation coming fron your cup of tea and othe objects near you. Also the detectot has a filter to pass only the narrow band radiation emitted by the RC so that the effect of broadband (thermal) IR from your tea cup, the room etc., is reduced. 2/"How does the EMR emitted by a microwave oven travel from the cold walls of the oven to the warmer food being cooked?" - The microwave energy is repeatedly reflected by the walls until, sooner or later, it encounters the food to be cooked, where it is (mostly) absorbed. If there is no food in the oven the microwave energy builds up (there are warnings not to run the thing at full power when it's empty) and you will damage the device, possibly bustin the magnetron. 3/ "How does the EMR carrying radio and television broadcasts travel from the transmitter to warmer locations around it - rather than radio and television being routinely interrupted by minor local temperature variations?" - Same as 1/, except the transmitter is not focussed (much). 4/ "Heck, how does the EMR of 'sunlight' travel from the cold of space to the warmer upper atmosphere to the warmer still lower atmosphere? By your claims we should all live in perpetual darkness because sunlight cannot approach the warmer surface of the Earth." - The Sun is at about 5780K and that has the spectrum we see (well, our eyes do not see the infrared (IR) and ultraviolet (UV) but it is stil there). The Sun occupies only a small part of the sky so we do not get a the full 5780K here, only 279K. But sunlight still behaves with some of the properties of a 5780K source, it ionises O2 in the stratosphere to make ozone and it tans your skin, burning it if you are not careful. For the rest - no comment.
  22. Re #818 Tom Curtis you wrote:- "Following damorbel's logic @815" - no comment.
  23. LJR, by definition, if the ability to radiate is decreased, the emissivity does change and the blackbody becomes grey. How else can it possibly manifest? It has been pointed to you earlier that this is exactly what the atmosphere does. And what was this thing again with the cooker cooler below ambient but in fact staying at the same temperature as the air? This is a waste of time.
  24. damorbel #819: We already covered this nonsense... you claim EM radiation behaves differently when reflected than it does when absorbed and re-emitted. Again, irrelevant even if it weren't completely false. Real world examples of each; Photographer taking a picture of a 'penguins on ice' exhibit in a zoo. The ice is colder than the mirror in the camera and the film yet the image is carried by the EM radiation from cold to hot. The ice does not 'disappear' from the picture. EMR flowing from a cooler object to a warmer one while being reflected along the way. Two identical pots of water on an electric stove. Heat them both to the maximum temperature of the stove for an extended period and then turn one off while putting the other at half heat. If energy were unable to travel from cold to hot then the pot which was warmed up to the maximum heat could not absorb and re-emit heat from the now half as hot burner and would therefor cool down at exactly the same rate as the pot whose burner was turned off (until it reached half heat and stopped cooling). Yet this does not happen. The pot with half heat cools down slower / remains boiling much longer than the pot with no heat... because even though it is (initially) hotter than the burner it is still receiving additional heat... heat flowing from a cooler object to a warmer one by absorption and re-emission. One example involves reflection, the other absorption and re-emission. Yet both show energy flowing to a cooler area from a warmer one. Ergo, the reflection vs absorption and re-emission distinction you keep making is meaningless. It is observed reality that energy can and does flow from cold to hot in either case. Your arguments continue to be complete nonsense... and you continue to avoid any attempt to address the countless real world examples proving that. damorbel #820: You attribute a quotation from message #804 to me. It was actually written by KR.
  25. damorbel #821: "Remote controls emit high brightness narrow band IR that is focussed; the detector at the receiver can distinguish the RC bright spot against yhe background radiation coming fron your cup of tea and othe objects near you." The question isn't how the receiver distinguishes the signal from the remote from ambient energy (which you get completely wrong BTW). It is how it receives the signal at all if, as you claim, energy cannot flow from the cold remote to the warmer receiver. "The microwave energy is repeatedly reflected by the walls until, sooner or later, it encounters the food to be cooked, where it is (mostly) absorbed." But how? Are you amending the 2nd law of thermo-ridiculousness to; Energy cannot flow from cold to hot unless it is repeatedly reflected first? Still doesn't explain the remote control. "Same as 1/, except the transmitter is not focussed (much)." The IR remote isn't focused much either... which is why you can bounce the signal off a wall behind you and still have it work on the television (or whatever) in front of you. However, that still doesn't explain how either travels from cold to hot. "But sunlight still behaves with some of the properties of a 5780K source, it ionises O2 in the stratosphere to make ozone and it tans your skin, burning it if you are not careful." So now you are claiming that only the temperature of the 'origin point' of the EMR matters... it can go through cooler and warmer areas so long as none is warmer than the origin point. Yet the remote, microwave, and radio examples all show EMR traveling to areas warmer than their origin points.

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