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The greenhouse effect and the 2nd law of thermodynamics

What the science says...

Select a level... Basic Intermediate
The 2nd law of thermodynamics is consistent with the greenhouse effect which is directly observed.

Climate Myth...

2nd law of thermodynamics contradicts greenhouse theory
 

"The atmospheric greenhouse effect, an idea that many authors trace back to the traditional works of Fourier 1824, Tyndall 1861, and Arrhenius 1896, and which is still supported in global climatology, essentially describes a fictitious mechanism, in which a planetary atmosphere acts as a heat pump driven by an environment that is radiatively interacting with but radiatively equilibrated to the atmospheric system. According to the second law of thermodynamics such a planetary machine can never exist." (Gerhard Gerlich)

 

Skeptics sometimes claim that the explanation for global warming contradicts the second law of thermodynamics. But does it? To answer that, first, we need to know how global warming works. Then, we need to know what the second law of thermodynamics is, and how it applies to global warming. Global warming, in a nutshell, works like this:

The sun warms the Earth. The Earth and its atmosphere radiate heat away into space. They radiate most of the heat that is received from the sun, so the average temperature of the Earth stays more or less constant. Greenhouse gases trap some of the escaping heat closer to the Earth's surface, making it harder for it to shed that heat, so the Earth warms up in order to radiate the heat more effectively. So the greenhouse gases make the Earth warmer - like a blanket conserving body heat - and voila, you have global warming. See What is Global Warming and the Greenhouse Effect for a more detailed explanation.

The second law of thermodynamics has been stated in many ways. For us, Rudolf Clausius said it best:

"Heat generally cannot flow spontaneously from a material at lower temperature to a material at higher temperature."

So if you put something hot next to something cold, the hot thing won't get hotter, and the cold thing won't get colder. That's so obvious that it hardly needs a scientist to say it, we know this from our daily lives. If you put an ice-cube into your drink, the drink doesn't boil!

The skeptic tells us that, because the air, including the greenhouse gasses, is cooler than the surface of the Earth, it cannot warm the Earth. If it did, they say, that means heat would have to flow from cold to hot, in apparent violation of the second law of thermodynamics.

So have climate scientists made an elementary mistake? Of course not! The skeptic is ignoring the fact that the Earth is being warmed by the sun, which makes all the difference.

To see why, consider that blanket that keeps you warm. If your skin feels cold, wrapping yourself in a blanket can make you warmer. Why? Because your body is generating heat, and that heat is escaping from your body into the environment. When you wrap yourself in a blanket, the loss of heat is reduced, some is retained at the surface of your body, and you warm up. You get warmer because the heat that your body is generating cannot escape as fast as before.

If you put the blanket on a tailors dummy, which does not generate heat, it will have no effect. The dummy will not spontaneously get warmer. That's obvious too!

Is using a blanket an accurate model for global warming by greenhouse gases? Certainly there are differences in how the heat is created and lost, and our body can produce varying amounts of heat, unlike the near-constant heat we receive from the sun. But as far as the second law of thermodynamics goes, where we are only talking about the flow of heat, the comparison is good. The second law says nothing about how the heat is produced, only about how it flows between things.

To summarise: Heat from the sun warms the Earth, as heat from your body keeps you warm. The Earth loses heat to space, and your body loses heat to the environment. Greenhouse gases slow down the rate of heat-loss from the surface of the Earth, like a blanket that slows down the rate at which your body loses heat. The result is the same in both cases, the surface of the Earth, or of your body, gets warmer.

So global warming does not violate the second law of thermodynamics. And if someone tells you otherwise, just remember that you're a warm human being, and certainly nobody's dummy.

Last updated on 22 October 2010 by TonyWildish.

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Related Arguments

Further reading

  • Most textbooks on climate or atmospheric physics describe the greenhouse effect, and you can easily find these in a university library. Some examples include:
  • The Greenhouse Effect, part of a module on "Cycles of the Earth and Atmosphere" provided for teachers by the University Corporation for Atmospheric Research (UCAR).
  • What is the greenhouse effect?, part of a FAQ provided by the European Environment Agency.

References

Comments

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Comments 651 to 700 out of 1393:

  1. les 638

    No not Maxwells Demon, but rather Kirchhoff's black body theorisation.
  2. Re #649 les, you wrote:-

    "damorbel 648 - fine. We agree on so much including, it would seem, that the diagram is not "completely deficient in temperature information". "

    I think there is a definite problem there. I'm afraid I do not understand just what is it that makes you say:-

    " the diagram is not "completely deficient in temperature information". ?

    and:-

    "It clearly does "present ... useful information for any discussion on climate change "

    I'm not sure what you mean here. I am of course thinking of 'useful information' in the sense of scientific information, suitable for putting in reports called 'the Scientific Basis', the name of the sections of IPCC reports using this diagram.

    Trenberth's diagrams are among the few (perhaps only) in IPCC reports showing directional energy effects from greenhouse gases, I cite them because, without temperature, any figures showing energy emissions from the atmosphere, the Earth's surface or anything else have no scientific basis.
  3. LJ@651
    >Sounds like a violation of the 1st law...remember perfectly reflective walls. Sounds as if you don't believe your own answer.

    The full context of that comment was:
    "... in practise you would not have perfectly reflecting walls,"

    So his assumption with that statement was that in reality you cannot have perfectly reflecting walls. Now stop trying to nitpick and give his example some real thought.

    >ok lets assign three wavelengths and redo @646

    As Tom pointed out this would just be a multiplier i.e. energy per photon X number of photons. To convert wavelength into energy per photon, use the equation h*c/wavelength. You can type this directly into google like so "h * c / 11364 nm". Once you have that number is just a matter of multiplying it by the number of photons, try it yourself.

    Re: question 1a)
    The aperture he is referring to is the open hole where the lid used to be. There is no aperture in Tom's original example.

    Re: question 2a)
    The lid still holds the same properties it did in the original example, i.e. it transmits 50% and reflects 50%.
  4. 653 damorbel: again, we are in complete agreement in not completely understanding the bits where I quote you. Still, to do what you require follow the advice of others here and read the full papers rather then looking at the pretty pictures.

    652 Ryan, well, no actually. Not for that weird selective filter thing. Still, given the arbitrary was bits of physics are being thrown around this thread; have it your way, what the hell!
  5. LJ@651 >So the accumulated "boxed" light would radiate 1W for a 100 hrs, once the second aperture is opened?

    The wattage of the aperture would be entirely determined by the the size of the hole, the size of the box, and the amount of energy in the box. As the energy escapes from the box the wattage of the aperture decreases.

    It has no relationship to the original wattage of the flashlight. That value is determined by the flashlight's ability to convert chemical energy into radiant energy. In this example all the energy is already radiant. The box doesn't "remember" the wattage of the original light source.
  6. L.J Ryan@651
    "So the accumulated "boxed" light would radiate 1W for a 100 hrs, once the second aperture is opened?"

    Wouldn't that depend on the size of the aperture? On the photon level wouldn't the "flow rate" out of the aperture change as less light remained in the box? Fewer photons would be available to hit the target/sec. I imagine it would be a bright and rapidly fading light once the hole was opened. Since this is all imaginary...
  7. e654

    "So his assumption with that statement was that in reality you cannot have perfectly reflecting walls. Now stop trying to nitpick and give his example some real thought."

    The perfectly reflective wall was Tom constraint not mine. Violating the 1st law in order to illustrate radiative forcing is not nitpicking, rather it's very fundamental. To say emissivity >0 leads to "light decay" is a convenient concept...does the photon slow down until comes to rest at the bottom of the box? What is light decay?

    Tom said:
    "The answer has to be in terms of photon numbers, not energy because the wavelength of the photons has not been specified. If we specify that all photons have the same wavelength, then the multipliers for photons in the answers above can be used for energy."

    you say:
    "To convert wavelength into energy per photon, use the equation h*c/wavelength. You can type this directly into google like so "h * c / 11364 nm". Once you have that number is just a matter of multiplying it by the number of photons, try it yourself."

    You seem to be at odds with Tom. Your suppositions concludes, regardless of wavelength the accumulated ENERGY within the box is twice the input...as detailed by @646
  8. e656
    pbjamm657

    Make the aperture diameter 2x photon diameter, and shazam you have a flashlight powered photon laser.
  9. LJ>

    Everything you said in post 658 is false. I will not detail the problems because they are all simple reading comprehension errors. If you're not going to make any effort to read and comprehend the point that is being made then you are not here for intelligent discussion; there's no point in talking to you.
  10. les655

    "Ryan, well, no actually. Not for that weird selective filter thing. Still, given the arbitrary was bits of physics are being thrown around this thread; have it your way, what the hell! "

    I agree sloppy physics, lot fundamental violations. The weird filtering was Tom's not mine.

    Are you familiar with Kirchhoff's black body cavity theorisation/experiment?
  11. e 660

    I asked a question...What is light decay?

    You are not contradicting Tom,suit yourself.
  12. LJ>

    In that specific comment, Tom clearly indicated he was talking about a "real-world" box that would not be perfectly reflective. In that case "decay" would be the light escaping the box. I have not contradicted a single thing Tom said, you just aren't reading what's being written.
  13. The energy quality I described in 498 is obviously related to the inverse of entropy, but people struggle with the latter concept. It is easier to see that quality is related to useful energy – that is, energy that can actually do something, such as producing useful work or raising temperature.

    In any spontaneous transaction involving energy transfer, quality will diminish. What this means is that the energy cannot go backwards, and some of the useful energy will be lost. (I said I would not mention the second law, but that is what it is really about). Incidentally, 499, real life energy losses through friction, etc, make the situation worse. Energy quantity as well as quality is lost to the system

    Here is another elementary example. An insulated vessel contains gas at a high temperature, and is separated from a vacuum, within the vessel, by a membrane. If the membrane is punctured, the gas flows into the vacuum, and its pressure drops. No work is done, no heat is lost, so the temperature remains the same.

    The first law says that energy has been conserved. But the gas is obviously able to do less work, starting from the lower pressure. It is also obvious that (Maxwell's demon apart) the gas cannot go back. What has happened is that the quality of the energy has fallen.

    It turns out (as the pundits say) that it is this elusive characteristic of quality (strictly entropy) that drives all spontaneous transactions – literally everything from chemistry, biology, energy transfer and (fancifully) the tidiness of your desk. It is the quality of energy, not the quantity, that makes something happen. Here are two well known examples.

    Suppose that a single gas flame operates at a temperature below the melting point of a steel plate. The steel will not melt because the quality of the flame energy is too low. Now apply ten more similar flames. Still the steel will not melt.

    Another example is Einstein’s experiment to eject electrons (I forget from what) with a beam of incident radiation. Below a certain frequency (energy quality) nothing happened, no matter what the intensity (energy quantity). Above that frequency, electrons were ejected, and quantum mechanics was born.

    Sadly, however, my definition of quality (available energy) is too simplistic. It is the relative quality that matters. Switching the argument to a power generator, a source with a high temperature can generate work by transferring energy to a sink at a lower temperature. The available energy is high. If the sink is at the same temperature as the source, nothing will happen. There is no available energy.

    Likewise, if the sink energy can be connected to a second sink with a lower temperature, space heating is possible. Otherwise the waste energy will be ejected to the atmosphere through cooling towers.

    So, if I have persuaded anyone that the crucial elements of energy transfer are the qualities of the energies concerned, and that energy can’t go backwards without the performance of extraneous work, we can move on to an even more elusive concept.

    Heat.
  14. Fred Staples - That's a fairly reasonable (if wordy) description of Entropy. You could have just linked to an existing definition and saved much typing.

    I think I see where you're going - to an argument that the high levels of IR at the surface somehow violate entropy considerations. You might find my comment here relevant in that regard. We aren't dealing with a closed system, but rather a very open one, where the important issues are rate of energy flow, energy differentials, and internal temperatures and energy levels required to maintain a dynamic equilibrium. Not moving a fixed amount of energy around a closed system.

    Entropy is increasing as sunlight radiates out into the 3K void of space. Local conditions regarding the conversion of that visible light into thermal IR provide a pinch-point, much like the dam in my analogy, one that includes a local collection of energy in order to have an energy differential sufficient to radiate the IR to space.
  15. L.J. Ryan - back to the original light box. We agree that the set up does NOT violate 1st law? No where in the system is energy being created. The thing that seems counter-intuitive apparently is that energy-fluxes appears to double. Whoa! energy creation! No. This illustrates that care has be taken in inferring system energy from energy flux, because in this case, with reflection, the same energy gets counted twice. This is no violation of 1st law going on in Tom's example - nor in Trenberth's diagram for same reason. Just an illustration about care in use of energy flux.
  16. Re 650 RickG :-
    "For what Trenberth is demonstrating temperature is neither necessary or relevant in that diagram. I have no problem understanding the diagram myself."

    It is difficult to believe that a diagram showing emission of thermal radiation (W/^m2) can be considered useful when no indication is given of the temperature of the emitting body; why else would the Stefan-Boltzmann equation (E= rhoT^4) be so widely deployed in thermal physics?
    Response: [Muoncounter] you raised this identical 'objection' in November, 600 comments up this very thread. The same replies you received then still apply now. Insistence on mere repetition demonstrates that your argument ran its course.
  17. damorbel
    given that you know how to calculate temperature from the energy flux, why are you asking Trenberth to report it in a summary graph? You really look polemical here, it adds really nothing to the discussion or to the undersdtanding of the energy budget.
  18. L.J Ryan@559
    No you would not have a laser, the beam would not be directional since photons would reach the aperture at a variety of angles and travel out that way too. From a photon=particle bouncing around standpoint I think the brightness of that beam would diminish over time as the number of photons hitting the aperture/sec would diminish along with the number in the box.

    "Light Decay" in the context of the discussion is light losing energy to the imperfect mirrors.

    As for Tom Curtis' original diagram @615 I think the missing element in most of this discussion is time. Over time A=C but not for every photon interaction. We need to be clear if we are talking about an instantaneous measurement or the totals over time. Same goes for the Trenberth Diagram.

    note: I am not a physicist nor mathematician. I reserve the right to be wrong.
  19. scaddenp666

    Oh...Tom and Trenberth count the photon/flux twice. So the vector sums are zero, no atmospheric forcing...no AGW. You have confirmed my position.
  20. L.J. Ryan - Since the Trenberth numbers are an energy budget, they should add up and cancel out for an unforced climate.

    If, however, you carefully add up the Trenberth numbers without rounding you get an imbalance of about 0.9 W/m^2 less leaving than arriving. That's the forcing.
  21. 661 Rysn good try at a twist. I'm afraid that it's transparent to all here that you really are not "doing physics" in your argumentation.

    At thus stage, really, we're just playing with you. Dont take your arguments so seriously - no one else is.
  22. damorbel,

    The diagram, or schematic as Trenberth calls it, is from one of his many PowerPoint presentations. In other words the schematic is meant to be presented with discussion in context with his presentation.

    The schematic as many of us have pointed out to you is about incoming solar energy and how it is distributed throughout the climate system taking different forms of energy. In describing this, not only by Trenberth, but all scientists, use the proper units of measure which is watts per square meter, not temperature.

    But since no one seems to be able to convince you of that, watch Trenberth describe that very schematic himself in this video.
  23. " So the vector sums are zero, no atmospheric forcing...no AGW. You have confirmed my position."

    Umm, this is about whether the GHE is consistent with thermodynamics. If it is, the adding CO2 will create forcing as KR has pointed out. (and is measured at TOA).

    Now the numbers on Trenberth are derived from measurement and the flux has to be consistent with temperatures. The light box discussion is about understanding why these fluxes are not a violation of 1st law.
  24. Fred Staples @664:

    Considering the example of the steel beam, the flames will not melt the steal beam because they will (eventually if it is well insulated) heat the steal to their own temperature. At that point the black body radiation from the steel will carry the same energy as the flames preventing further warming.

    Applying that example to my light box model, the photons leaving the box will never have a shorter wavelength (= higher temperature) then the photons leaving it. Nor will there be more of them on average, thus conserving energy.

    Applying that insight to the Greenhouse effect, that means the the surface of the Earth will never be hotter than the surface of the sun (ie, the temperature of the source of the energy that warms it), and the outgoing radiation will never have a shorter wavelength than the incoming solar radiation. You will struggle to find a prohibition against the greenhouse effect from these two facts.
  25. Tom Curtis 675

    "the Earth will never be hotter than the surface of the sun"

    The Earth receives 240W/m2 from the sun. The blackbody temp resulting from this flux represents the maximum temperature...not the sun's surface. That is, regardless of reflection and or re-radiation, 255K is the pinnacle temp for radiation alone. It is this fact by which blackbody was derived...trapping light in order to discover it's maximum thermal energy.

    ----clipped from another blog:

    The idea of trapping light is intriguing, and Gustav Kirchhoff (1824-1887) conceived a solution: A hole in a cave. A beam of light could enter this hole but the walls inside would absorb any reflections and prevent the light from escaping. Thus, by confining incoming radiation, the thermal energy which light confers could be shown to its maximum advantage. Kirchhoff's scheme was superior to selectively transmitting glass because a cave absorbs and traps all wavelengths of light,thus creating a complete radiative imbalance. At least theoretically.

    Well, so what was found by cavity experiments? That a perfectly absorptive ("black") body rises to a temperature a bit higher than an actual black body that’s free to radiate to its surroundings. A theoretical blackbody thereby defines the upper limit of temperature vs radiant absorption.

    Try to grasp the implication, then. A blackbody cavity mimics the radiative restriction that"greenhouse gases" are said to induce. Indeed, virtually none of the thermal radiation generated inside this cavity is allowed to escape. It "re-circulates" instead, and is sampled through a tiny hole. Does this confinement lead to a runaway greenhouse effect, though? No, it only sets an upper temperature limit — the SAME limit that’s applied to the earth in the first place, for its estimated temperature is based on a blackbody
  26. For anybody not convinced of AGW who has been following this discussion, consider the following model:



    In this model we have light entering a box (A) at an angle. It then strikes a mirror on the back of the box, is reflected of a mirror on the front of the box so placed that it does not block any incoming light. The now twice reflected light returns to the back of the box, striking the mirror once more. It then goes through a second transparent zone in the front of the box.

    Assume the ideal case in which all apertures are 100% transparent, all mirrors are 100% reflective and flat, and in which the light is so angled that neither the incoming beam (A) nor the outgoing beam (C) strike any part of the mirror on the top of the box. In that case, after sufficient time for light to transit the box three times, and with a constant light source providing beam (A), then the box will have the following equalities:

    1) Incoming light (A) = Outgoing light (C) (by virtue of conservation of energy).

    2) Light reflected from the lid (D) = Outgoing light (C).

    3) Light reflected from the back = light striking the underside of the lid (B) = light transmitted by the lid (C) plus light reflected by the lid (D) (by virtue of conservation of energy). This may require a little clarification. The lid consists of three sections in this model, two transparent, and one mirrored on the underside. One transparent section allows in the incoming light (A). The other allows out the outgoing light (C). So the light striking the back of the lid equals the light striking the mirrored section plus the light striking the transparent section through which the light exits.

    Therefore
    4) Light reflected from the back of the box (B) = light reflected from the back of the lid (D) plus Incoming light (A) = 2 x A (again, by conservation of energy.

    Such a box clearly does not violate any law of thermodynamics. If it did violate such laws, so much the worse for those laws, for the box could be set up as a primary school science project, and will behave as advertised. As I assume that the scientists of the world are not part of a massive conspiracy to foist upon us "laws" that can be refuted by any primary school kid with a plate of glass and two mirrors, I will take it that this box does not violate the laws fo thermodynamics is beyond dispute.

    However, having said that, we should notice that in each time interval equal to the time it takes a photon to travel from the lid to the back wall:

    5) the accumulated photons at equilibrium is 4 times the number of photons that enter the light box at each time interval; and

    6) at equilibrium the number of photons reflected in each time interval is 3 times the number that enter the light box in each time interval. Of those, 2 times that number are reflected of the back wall, and a number of photons equal to the number that enter are reflected of the lid. This ignores reflections of the side walls which are irrelevant to the overall issue.

    Now, reconsider this model:

    The description of the model is found in comment 615 above. Essentially, however, it is the same model as above, except the lid is replaced by a lid which lets in all light from outside and reflects exactly half of light from the inside, transmitting the remainder. The walls are perfectly mirrored.



    After equilibrium is established (ie, in approximately 20 times the time it takes for light to travel from the lid to the back of the box, see Phil's comment @624 and my comments @626 and @640 above), the equalities (1) to (4) above hold of this box as well (with appropriate adjustment of wording - for exact wording see comment 615 above).

    However, the facts (5) and (6) also hold of this box (see comment 647 above). Now, these two facts, according to some people, create a problem for this model. According to those people, they cause it to violate the laws of thermodynamics. But as we have seen, our first model (in this comment) has exactly these two properties, and does not violate the laws of thermodynamics. Therefore this model does not violate the laws of thermodynamics either. In fact, the only interesting difference between this model and the previous one is that this model takes about five times as long to reach equilibrium.

    So, having established beyond reasonable doubt that the simple light box does not violate the laws of thermodynamics, consider the following model:



    This model is quite different from the preceding two. For a start, (in the ideal case) the back and walls are perfectly absorbing on the inside, and perfectly reflective at all wavelengths on the outside. This means any light entering the box will be absorbed by the box, warming the back of the box. We also suspend the box in a vacuum so that energy can only escape by radiation. Because the outside of the walls and back are perfectly reflective, this means they have zero emissivity and energy can only escape through the lid.

    The lid itself has (in the ideal case)perfect thermal isolation from the sides, and back (which means the box contains a vacuum). It is perfectly transparent to all light below a certain wavelength, and perfectly absorbing for all wavelengths above that amount. It (and the back and walls of the box) is also a perfect thermal conductor so that its outside and inside have exactly the same temperature.

    Importantly, the wavelength of the incoming light is less than the critical wavelength of the lid. Also, for simplicity, the total energy of the incoming light is less than the amount at which the shortest wavelength of a black body emission from the back and sides of the box is shorter than the critical wavelength.

    Given these conditions, when you start shining light on the box, the back and sides will heat up and start emitting long wave length radiation. Because all of that radiation has a wavelength longer than the critical value of the lid, the lid will in turn start heating up and emit radiation. Eventually the energy emitted outwards (C) will equal the energy of the incoming light (A), at which time equilibrium has been reached.

    At that time, the following equalities will hold:

    1) Incoming energy (A) = Outgoing energy (C) (by virtue of conservation of energy).

    2) energy radiated from the lid inwards(D) = Outgoing energy (C) (by virtue of both sides of the lid having the same temperature and emissivity).

    3) energy radiated from the back = energy absorbed by the underside of the lid (B) = energy radiated outwards by the lid (C) plus energy radiate inwards by the lid (D) (by virtue of conservation of energy).

    Therefore
    4) Energy radiated from the back of the box (B) = energy radiated inwards by the lid (D) plus Incoming energy (A) = 2 x A (again, by conservation of energy).

    It will also be true that:

    5) The accumulated energy in the box in the form of radiation will be four times the energy carried into the box by incoming light in the time it takes for light to travel from the lid to the back of the box.

    Indeed, an additional amount of energy will be stored in the back, sides and lids of the box depending on their heat capacity. That means the greater their heat capacity, the longer the box will take to reach equilibrium. That is simple a consequence of the incoming energy being diverted to heat the wall and lid, and therefore not being available to leave the box. It is only when the walls and lid reach a stable temperature that the energy is no longer used in the box, and will leave at the same rate it entered.

    Now, very clearly, these 5 facts mirror the first 5 facts in our first, and second model. Therefore, if those five facts do not cause the first two models to violate the laws of thermodynamics (which they do not), then these facts cannot cause the third model to violate the laws of thermodynamics. In fact, the only thermodynamically interesting difference between the first two and the third model is that in the first two, the leaving energy had an almost identical entropy to the incoming energy, whereas in this model, the leaving energy has a much higher entropy in virtue of its much longer wavelengths.

    The other interesting fact about this model is that it is an example of (not an analogy to, but an example of) the green house effect. It is a very simple example, but example it is none-the-less. And as this example does not violate any law of thermodynamics, it follows that the greenhouse effect does not violate any law of thermodynamics.

    QED
  27. Tom Curtis 677

    I compliment your thoroughness, though I see a couple problems with your examples. But first clarification. You said:

    "Importantly, the wavelength of the incoming light is less than the critical wavelength of the lid."
    Ok got it.


    "Also, for simplicity, the total energy of the incoming light is less than the amount at which the shortest wavelength of a black body emission from the back and sides of the box is shorter than the critical wavelength."
    Are you saying peak bb emissions are not transparent to the lid or the wavelength shorter then peak are not transparent or something else?
  28. LJR @678 the lid is not transparent to the shortest wavelength photons emitted as black body radiation by the back and sides. Clearly whether this is the case or not depends on the total energy of the incoming light, and hence needs to be stipulated.
  29. I have just noticed that one of my posts has been deleted by a moderator. I believe the required response, as exhibited continually by deniers on this site, is to claim that it is censorship, and that the moderators are plainly biased against my point of view ;)

    To the moderators - keep up the excellent work you do.
  30. Tom Curtis @677
    "As I assume that the scientists of the world are not part of a massive conspiracy to foist upon us "laws" that can be refuted by any primary school kid with a plate of glass and two mirrors, I will take it that this box does not violate the laws fo thermodynamics is beyond dispute."

    I had a similar thought over dinner tonight. The argument that AGW theory violates the Laws of Thermodynamics is a backdoor conspiracy argument. To accept this idea would require that all the worlds scientists are hiding such a fundamental error either through ignorance or willful deceit.
  31. Re #649 les, you wrote:-

    "damorbel 648 - fine. We agree on so much including, it would seem, that the diagram is not "completely deficient in temperature information". "

    I think there is a definite problem there. I'm afraid I do not understand just what is it that makes you say:-

    " the diagram is not "completely deficient in temperature information". ?

    and:-

    "It clearly does "present ... useful information for any discussion on climate change "

    I'm not sure what you mean here. I am of course thinking of 'useful information' in the sense of scientific information, suitable for putting in reports called 'the Scientific Basis', the name of the sections of IPCC reports using this diagram.

    Trenberth has updated his diagrams at least once, mainly changing the numbers, so I think the numbers are important; it would be most interesting to know why the numbers are changed, I have not found this in any of the links given, can you help?
  32. Can I suggest that TC's little demonstration be reconstitued as a response to "GHE violates 1st Law" (along with link to SoD's articles on same subject), and that the comment stream be moved there?
  33. Tom Curtis677

    I make reference to Kirchhoff's cavity experiment while you, without knowledge of my future post, are incorporating an example similar to my reference within your post...serendipitous.

    You have abandoned your position as stated in 647 that
    "The answer has to be in terms of photon numbers, not energy because the wavelength of the photons has not been specified. If we specify that all photons have the same wavelength, then the multipliers for photons in the answers above can be used for energy."

    In all three scenarios you are adamant about accumulated energy and just as adamant this in no way violates thermodynamic laws. So if one of these scenarios is shown to violate thermodynamic laws then all your scenarios do. And more importantly you said "The other interesting fact about this model is that it is an example of (not an analogy to, but an example of) the green house effect." So a violation within your examples PROVES a violation within GHG theory.

    Do you agree?
  34. LJR @684:

    1) My claim in 647 was about a particular model, model 2 in 677. It is true about that model. Model 3 in 677 is different, and analysis of that model in terms of photon numbers will not work.

    2) All three models do accumulate energy, and all three do not violate any of the laws of thermodynamics. However, if I am mistaken about that, and you are able to prove (not merely say, but prove) that the third model violates the laws of thermodynamics, it will not prove that the others do not. It may only prove that I am mistaken about their relevance to the debate.

    3) If you prove that the third model violates the laws of thermodynamics, you will not have proved that no possible implementation of a greenhouse effect can exist without violating the laws of thermodynamics. You will only have proved it of one case, all though that may make it easier to prove of all cases. This works both ways. If I prove that the 3rd model does not violate the laws of thermodynamics, it is still possible that other examples of the greenhouse effect do. Whether or not the green house effect in the Earth's atmosphere violates them will still be up for debate. What will not be up for debate is whether the fact it is a greenhouse effect is sufficient to prove that it violates the laws of thermodynamics. What I strongly suspect is that every feature of the actual green house effect in Earth's atmosphere which people point to as a reason to suspect violation of the laws of thermodynamics will also be a feature of model three, which will thereby disprove the claim that that feature proves a violation of the laws of thermodynamics.

    Which brings me to the main point. I have just proved that an example of the green house effect can exist without violating the laws of thermodynamics. You may not be able, or willing to follow the proof, but that is your look out, not mine. Given that, you persistence in concentrating only on complicated cases, and in trying to assume universal disproofs from particular instances suggests that you are just very confused. It suggests, in fact, that you cannot demonstrate your case, either to yourself or to others, in the simple cases. Consequently you must concentrate on complicated cases that allow maximum free play for misdirection.
  35. LJR @676, I like the continuation of that quote:

    "Now, it is very likely that applying a cavity-based formula to the temperature of a rotating
    half-lit sphere is inherently mistaken. But if not, then 279 Kelvin constitutes the upper limit for
    the earth because such an estimate assumes a body that is perfectly absorptive, meaning that it
    can’t possibly absorb more light than the light it’s exposed to."


    You would have thought that Alan Siddons, having noticed that the mean global surface temperatues is 287-288 degrees, and that much hotter temperatures than that are to be found on the Earth's surface would have noticed his experimental refutation and concluded that it was indeed, not just likely, but in this case proven that "...applying a cavity-based formula to the temperature of a rotating half-lit sphere is inherently mistaken". This is particularly the case when the formula for the cavity based temperature requires that the cavity by isothermal, while the rotating sphere is known to be anything but.
  36. damorbel@682

    "Trenberth has updated his diagrams at least once, mainly changing the numbers, so I think the numbers are important; it would be most interesting to know why the numbers are changed, I have not found this in any of the links given, can you help?"

    That's a good question and one in which the answer demonstrates the greenhouse effect very well.

    The first schematic is dated 1997 and the second schematic is dated 2009. I can't find any information on the '97 schematic but the '09 schematic states "The global annual mean Earth's energy budged from Mar 2000 to May 2004." Any time period differences of instrumental data are certainly going to have different values. However, the actual difference of total incoming solar radiation between the two schematics is only 1 W/m^2.

    The biggest difference is within the global climate system itself. Because I don't know the exact time period for the '97 schematic I'm going to use the time periods from publication dates (1997-2009) to illustrate those internal differences.

    As greenhouse gases increase we can also expect global temperatures to increase. From 1997 to 2009 CO2 increased from 363 to 387 ppm, an increase of 24 ppm. During this same period global average temp. increased by 0.19 K. Atmospheric water vapor is directly dependent up temperature. The higher the temp the higher the vapor content and vice versa. Therefore, we can expect energy flows in these systems to be different between those two different time intervals as they have different conditions. Other changes include the albedo due to deforestation and ice mass loss. Each of these affect the energy distribution and exchange..

    As I previously mentioned the schematic dated 2009 is one that Trenberth uses in a number of Power Point presentations. Looking at it and making specific assumptions questioning terminology and units of measure without his supporting context quite often leads to incorrect assumptions. I previously gave you a link to a video where he is describing the schematic. If not already, I do hope you will take the time to view the entire video for full context.

    Additionally, there is a paper by Trenberth, Fasullo & Kiehl titled "Earth's Global Energy Budget", where that specific schematic is discussed in great detail showing where all those numbers come from. The paper can be found here.
  37. 682 damorbel:

    My original reply was moderated, probably due to it being to patronizing; a mistake I wont repeat so you'll just have to take that as read.

    regarding "I'm not sure what you mean here."
    I was replying to your original, and wrong, assertion that the diagram doesn't consider temperature. It does as pointed out. I guess in reality do you understand that and you acknowledge that as you now change your requirements to something else...

    "I am of course thinking of 'useful information' in the sense of scientific information, suitable for putting in reports called 'the Scientific Basis', the name of the sections of IPCC reports using this diagram."

    to which, as other observe, you will have to read the rest of the material behind the diagram. There just is no getting away from having to do science if you are doing science.
  38. Tom Curtis 685

    1q) Photons work for models 1 & 2 but not 3. Ok what if we assign an input wavelength for 3?


    You said:
    "Given that, you persistence in concentrating only on complicated cases, and in trying to assume universal disproofs from particular instances suggests that you are just very confused. It suggests, in fact, that you cannot demonstrate your case, either to yourself or to others, in the simple cases. Consequently you must concentrate on complicated cases that allow maximum free play for misdirection. "

    I've already challenged your more simplified models...remember "practical difficulties do not prevent us from exploring theoretical possibilities in ideal cases." And your absurd conclusion of 360 kJ of "boxed" light. Then you walked back your conclusion by saying the light would "decay." post 647

    Your model three is just happens to mimic actual experiments, so the conclusions are verifiable with actual results... no decaying light, no misdirection.

    Because model three incorporates surfaces with emissivities >0, specifically blackbody surfaces, "accumulated" energy can actually be calculated. Further, because blackbody represents the maximum thermal conversion of all radiation, it also represents the maximum "accumulated" energy of your three models. That is, emissivities <1 absorb less radiation then blackbody therefore "accumulate" less energy...ergo if model 3 is proved to have zero "accumulate" energy models 1&2 also have zero accumulated energy.

    Do you agree?
  39. Tom Curtis 686

    Thanks for providing a hyperlink. Cut and paste is tedious to format.

    I also like the following comment/paragraph...but in it's entirety.

    "Now, it is very likely that applying a cavity-based formula to the temperature of a rotating half-lit sphere is inherently mistaken. But if not, then 279 Kelvin constitutes the upper limit for the earth because such an estimate assumes a body that is perfectly absorptive, meaning that it can’t possibly absorb more light than the light it’s exposed to. Doing everything a "greenhouse effect" is alleged to do, continuously re-radiating infrared energy inside itself, a light-trapping blackbody demonstrates that radiative forcing is a fiction. For its temperature hits a ceiling not much higher than what you see in real life. Yet greenhouse theory claims that radiative restriction generates temperatures HIGHER THAN a blackbody’s. And considerably higher at that. Such a claim overtly contradicts experimental evidence, then. It doesn't have an empirical leg to stand on. First seized upon as the answer and later dismissed, a glass enclosure proved that infrared opacity had nothing to do with generating extra heat inside. Then came the radiatively restricted blackbody, which nailed the forcing concept shut. Yet against all evidence climatologists still push the radiative forcing theory. WHY?"

    You said:
    "You would have thought that Alan Siddons, having noticed that the mean global surface temperatures is 287-288 degrees, and that much hotter temperatures than that are to be found on the Earth's surface would have noticed his experimental refutation and concluded that it was indeed, not just likely, but in this case proven that "...applying a cavity-based formula to the temperature of a rotating half-lit sphere is inherently mistaken"

    Addressing GHG theory flaws is not the same as explaining why surface temperatures are 33 degrees higher then blackbody. Precluding the later does not nullify the previous. We can move onto a scientifically sound explanation for the 33 degrees, but lets first conclude the argument at hand.
  40. Re 650 RickG :-
    "For what Trenberth is demonstrating temperature is neither necessary or relevant in that diagram. I have no problem understanding the diagram myself."

    It is difficult to believe that a diagram showing emission of thermal radiation (W/^m2) can be considered useful when no indication is given of the temperature of the emitting body; why else would the Stefan-Boltzmann equation (E= rhoT^4) be so widely deployed in thermal physics?

    You say you 'have no difficulty understanding the diagrams', then it is probably my fault, I must be looking at them the wrong way; would you mind saying just what it is that you understand, please?
  41. Re My Posts.

    To those who have noticed:-

    A number of my posts appear twice, I regret this very much, it is nothing personal but for most of today my attempts to post have failed; I tried the usual rebooting without success. Now I have reinitialised through the home page and see that some these posts now appear more than once; seems to be a glitch somewhere. Rather embarrassing; sorry.
  42. Re #668 Ricardo

    "given that you know how to calculate temperature from the energy flux"

    I'm afraid I don't; it is temperature calculation that defines the whole 2nd law objection. The 2nd law is about energy transfer and it states that it is a function of two temperatures. To know the rate of energy transfer between two places, as an absolute minimum both the energy source temperature and the energy sink temperature must be known.

    The sink temperature may be 0K, that is the basis of Stefan's law, it gives the maximum possible energy transfer because no object can have a lower temperature than 0K. If the sink temperature is not 0K the energy transfer is less than the figure given by Stefan's law.

    If you think of it this way you will see this is the reason why bodies with the same temperature do not exchange energy, neither of them can be an energy source or an energy sink; thermal equilibrium exists!

    There is another reason why Trenberth's diagram tells us nothing. Yes I noticed that the figures he gives could be derived from Stefan's law, but only if you assume the places he gives as sources, e.g. TOA, act like black bodies. This is simply not possible; the TOA is quite transparent, so it can't possibly meet the definition of a black body.

    Just having the spectrum of a black body, like a grey body (it's a gas! It doesn't even have that!) is not sufficient to qualify the TOA as a black body; so any figures for enegy transfer in the atmosphere based on Stefan's law will be quite misleading.
  43. LJR @689:

    "I've already challenged your more simplified models...remember "practical difficulties do not prevent us from exploring theoretical possibilities in ideal cases." And your absurd conclusion of 360 kJ of "boxed" light. Then you walked back your conclusion by saying the light would "decay." post 647"


    To start with, that was your simplified model, not mine. Second, I did not "walk back" from my conclusion. I distinguished between the ideal case (3600 kJ accumulated) and every possible practical case (the light would escape or be absorbed by the mirrors before internal storage could be measured or stored). What I was noting was that it would be impossible to set up an experiment that tested your model. In contrast, in each of my models, an experiment could be set up which would be able to test the conclusion (even though they would not match exactly the ideal case) Your inability to master simple reading comprehension is not my problem.

    "Because model three incorporates surfaces with emissivities >0, specifically blackbody surfaces, "accumulated" energy can actually be calculated. Further, because blackbody represents the maximum thermal conversion of all radiation, it also represents the maximum "accumulated" energy of your three models. That is, emissivities <1 absorb less radiation then blackbody therefore "accumulate" less energy...ergo if model 3 is proved to have zero "accumulate" energy models 1&2 also have zero accumulated energy.


    By accumulate I mean:

    A) Once the incoming light starts, it takes more time than the time it takes for light to transit the box twice for equilibrium to be reached;

    B) If the incoming light is removed, it would take more time than it takes for light to transit the box twice for outgoing energy to cease; and

    C) The total energy inside the box once equilibrium is reached is greater than the total energy in an equal volume of vacuum immediately above the box through which only the incoming radiation and outgoing radiation transit, ie, there are no extraneous bodies.

    I believe these stipulations follow from the standard definition of "accumulate", but I believe in your case it is necessary to be precise.

    Given the above meaning of "accumulate", yes, energy accumulates in all three boxes, and, if you can prove that there is zero accumulated energy in any box, you have proved it in any (as every proposition follows from a contradiction).
  44. damorbel: It is difficult to believe that a diagram showing emission of thermal radiation (W/^m2) can be considered useful when no indication is given of the temperature of the emitting body; why else would the Stefan-Boltzmann equation (E= rhoT^4) be so widely deployed in thermal physics?

    All I can say is I don't know of a single climatologist on the planet when describing the Earth's Energy Budget, uses anything other than W/m^2. If you are unwilling to accept that simple fact, then I suggest you redo Trenberth's schematic in your terms of temperature and show everyone how it should done.
  45. Tom Curtis 695

    You said:

    "By accumulate I mean:

    A) Once the incoming light starts, it takes more time than the time it takes for light to transit the box twice for equilibrium to be reached;

    B) If the incoming light is removed, it would take more time than it takes for light to transit the box twice for outgoing energy to cease; and

    C) The total energy inside the box once equilibrium is reached is greater than the total energy in an equal volume of vacuum immediately above the box through which only the incoming radiation and outgoing radiation transit, ie, there are no extraneous bodies."

    What about the specific quantifier of accumulate, as stated by you:

    "5) The accumulated energy in the box in the form of radiation will be four times the energy carried into the box by incoming light in the time it takes for light to travel from the lid to the back of the box."

    Acceptable or not?
  46. LJR @696, once the box reaches equilibrium, the amount of energy in each box as radiation is 4 times the energy carried into the box in the time to takes for light to travel from the front to the back of the box (1 time unit). It is two times the amount of energy in an equivalent space above the box one time unit after the box has reached equilibrium. Whether this should be expressed as the box "accumulating" four times or two (or possibly three) times the amount of energy that enters the box in one time unit, I'm not sure. It certainly contains four times the radiant energy entering in one time unit. The third model also contains (and accumulates) an additional amount of energy depending on the thermal capacity of the back and sides, and the lid. Whether the radiant energy accumulated is 4, 3, or 2 times the energy entering the box in one time unit depends on the precise definition of "accumulate" that we us, and as you evidently want to run through this with a ultra-fine tooth comb, we do need to be very precise. Whatever the definition of accumulate we use, however, the facts stated at the start of this post are sufficient to allow any disproof (or proof) of my claims.
  47. Tom Curtis 697 Part I

    Working with your model 3 lets assign a starting wavelength of 580 nm at the input which converts to 3.43 e-19 J = A

    The emissions of < 580 nm via the back wall, radiate through the filter lid. 580 nm and longer are re-radiated via the filter lid. If the physics work as you suppose, the energy is accumulating within the box. The subsequent absorption, radiation and re-radiation will result in equilibrium, whereby 4A = 1.37 e-18 J of accumulated energy.

    Do you agree?
  48. LJR 698, I get 3.4249 * 10^-19 Joules per photon myself, and hence four times that energy contained in the box. I have to wonder, however, why are you just feeding the box 1 photon at a time. If the feed rate is 1 photon per second, that represents a temperature of just 0.0016 degrees K, ie, beyond the range of experimental detection. Even if the box is one meter thick so that you are feeding in 299,792,458 photons per second, the temperature of the lid will still only be 0.2 degrees K.

    That is perfectly fine for a thought experiment, but in that case why not just set the incoming energy as 1 Joule per time unit, and set the time unit as 1/300,000,000 of a second for convenience. For a practical experiment, the values you have chosen are two small to be measurable.
  49. Re #695 RickG you wrote:-

    "All I can say is I don't know of a single climatologist on the planet when describing the Earth's Energy Budget, uses anything other than W/m^2."

    Is this a reason to accept it? Doing it the W/m^2 way without temperatures has, from the thermal physics point of view (even Newton knew it was wrong), never been justified; it is unjustifiable.

    Again, you wrote:-
    "If you are unwilling to accept that simple fact, then I suggest you redo Trenberth's schematic in your terms of temperature and show everyone how it should done."

    Trenberth's diagram is deficient in so many ways it is beyond revision.

    The so-called 'back radiation' has the concept behind it that there is a place in the atmosphere from where 'back radiation' comes; but even John Tyndall knew that this is not the case. He measured both the emission and absorption by GHGs and found that their emitted radiation was completely absorbed by gases at a lower temperature.

    This last means radiation emitted by GHGs is immediately absorbed and re-emitted by adjacent GHGs. This is so when the pressure and temperature gradient are zero; in the atmosphere the density reduces with altitude so the upwardly emitted radiation is not completely reabsorbed, an increasing %age gets ever higher until it escapes completely; that is the mechanism for heat radiation from the Earth.
    Response: [muoncounter] The only thing deficient in this thread is your continued repetition of the same 'objections' to the same accepted body of work. What is preventing you from taking your comments to Dr. Trenberth, rather than belaboring them here?
  50. domorbel @ 700: Trenberth's diagram is deficient in so many ways it is beyond revision.

    Since I asked you to post your revised edition correcting Trenberth's short-comings on how it should appear, I gather your above comment is code for you can't support your claims?

    The data that goes into the schematic is massive and from numerous independent sources including ISCCP-FD, NRA, ERA-40, JRA, WHOI and HOAPS. It is not an ad-hoc meaningless diagram as you claim.

    "Again", read and absorb the paper (Earth's Global Energy Budget) by Trenberth et al that displays and explains the schematic in vivid detail.

    Here's the link: http://www.cgd.ucar.edu/cas/Trenberth/trenberth.papers/BAMSmarTrenberth.pdf

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