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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 751 to 800 out of 1393:

  1. For myself, Tom, I kinda like your box idea. It could be called a path lengthening device, increasing the number of photons in the system at a given time. Time is often the missing idea when considering GH effect. At equilibrium, energy in and energy out at TOA are equal. Increase IR opacity and energy out at TOA becomes less than in, until the surface temp increases to radiate enough out through the increased opacity. There is no violation of thermodynamics at all.
  2. damorbel - I didnt describe any experiment. I proposed that an experiment be designed such that normal understanding of physics and your understanding would calculate a different result. This is normal way to test scientific arguments. I asked if the experiment didn't go your way, whether you would be prepared to abandon your view and read the textbook. (ie, behave like a scientist).

    Got a yes/no? In fact, have you got an experiment that you think validates your views over mainstream physics?
  3. CBDunkerson750

    You said:
    "In that both cause an area to be warmer due to redirected electromagnetic energy it isn't a matter of belief, but rather observed reality."

    Focusing a large radiative input to a specific point is NOT what proponents argue. Redirecting radiation is not a point of contention. What is disputed...a cold atmosphere warms the warmer earth.


    Google solar cooker. The principal works by redirecting radiation, (from a large area) to a small focal area. When facing the sun, the focal area (the small area) gets hot. When facing away from the sun the focal area (small area) gets cold.

    How can this be?

    Maybe you should understand what you proclaim to know.
  4. What is disputed...a cold atmosphere warms the warmer earth.

    No-one believes the cold atmosphere warms the warmer earth. The Greenhouse effect slows the rate at which heat escapes from the earth. Period.
  5. Just to make one thing clear.

    Photons from a 'hot' (5780K) source like the Sun can be refocussed at any distance (if the mirror is big enough) to recreate the surface temperature (5780K) of the source, but no higher.

    No amount of refocussing etc., etc., of photons from a cold (255K) source, like the upper troposphere, can produce a temperature higher than 255K... anywhere.

    It's the photons you see, they don't have enough energy.

    They may have all the power (W/m^2) you can imagine* but no amount of refocussing, adding together, accummulating in reflecting cavities etc., etc. will raise their energy. Or, in other words, increase the temperature of.... anything. That is what the 2nd law is all about.

    It why quantum theory holds sway. And why the 'GH' effect is not a radiation effect... from... GH gases.

    * Power is not energy. Power is W(atts); energy is J(oules).
    A surface emitting power has two options it can emit relatively few 'hot' photons to get power 'P'. Or it can emit a large number of low energy photons to get the same power 'P'.

    There is a lot of grief on this thread cause by contributors not distinguishing between power balance and energy balance by defining both as 'W/m^2', that is a mistake.
  6. Ryan

    I have read the entire thread, in case you've missed the numerous references to comments from November and December.

    You apparently have also missed the point about 'at the same frequency'; IR photons have considerably less energy than visible light photons. CBD's point here is quite valid, with or without the parabolic geometry (which is a mere artifact of your solar cooker analogy). You've not proved anything with it, except how much you are willing to argue for the sake of argument.
  7. Re #756 muoncounter

    That's exactly what #755 explains.

    In #750 CBD writes :-

    "In that both cause an area to be warmer due to redirected electromagnetic energy it isn't a matter of belief, but rather observed reality."

    No amount of redirecting, refocussing adding together etc.,etc., of photons can increase their energy: warmer the Earth's surface may well be but it is not a radiation effect*.


    *It is actually a gravity effect.
  8. CBDunkerson750

    You said:
    "In that both cause an area to be warmer due to redirected electromagnetic energy it isn't a matter of belief, but rather observed reality."

    Focusing a large radiative input to a specific point is NOT what proponents argue. Redirecting radiation is not a point of contention. I say cold atmosphere radiation can not shorten terrestrial radiation, GHG proponents say otherwise.

    Google solar cooker. The principal works by redirecting and focusing, from a large hot area, radiation to a small target area. When facing the sun (hot),the focal area (the small area) gets very hot. When facing away from the sun (the cold atmosphere) the focal area (small area) gets cold. So the small target area looses energy via the large area to the cold atmosphere. See this process (unlike the magic box) abides the 2nd law, Hot to Cold. The atmospheric LW does NOT accumulate within the target area. The target area looses energy to the radiating atmosphere. GHG physics concludes conversely.
  9. mods - I really do think that damorbel, and particularly 755 & 757 violates the comments policy.

    Although not exactly an ad hominem attack, it is an attack on the work of many, many physicists through the ages. On behalf of those upon who's shoulders most of us stand - bun on who's feet damorbel seems to be stepping, I pray you, make it stop!
  10. Ugh, LJ -- not the alleged solar cooker evidence. It is proof of nothing. The reflective surface focuses incoming radiation. That radiation could be coming from the atmosphere. Your argument is that we can't differentiate between radiative transfer and conduction/convective transfer. In other words, why doesn't the solar cooker cool to near absolute zero when pointed at the open night sky? Something must be heating it.

    (expected response)

    Ok, then put it in a clear vacuum box and point it at the night sky. With no internal heat source, and no way to receive energy (according to your physical model), it should cool down at its rate of emission (and internal conduction) until it reaches near absolute zero. I'll wager that it won't, though. I'll wager that it cools more slowly, because even if we warmed it up to 50C before we put it in the box it's still receiving infrared radiation from the atmosphere. Photons can't choose their paths.
  11. Re #760 DSL you wrote:-

    "Ok, then put it in a clear vacuum box and point it at the night sky. With no internal heat source, and no way to receive energy (according to your physical model), it should cool down at its rate of emission (and internal conduction) until it reaches near absolute zero"

    There is a comparable effect known as 'clear sky' frost; the condition when surface frost appears e.g. on car windshields, even when the air teperature is not below freezing.

    In this situation radiation through the intervention of GHGs is exchanged with the higher levels of the troposphere which are below freezing. Some of the xchange might well be with deep space, but only a small part; which of course cannot easily be separated out.
  12. #754. Thanks Phil

    Glad that everyone's agreed on that one!
  13. damorbel@761
    "In this situation radiation through the intervention of GHGs is exchanged with the higher levels of the troposphere which are below freezing. Some of the xchange might well be with deep space, but only a small part; which of course cannot easily be separated out."

    Would you please expand on this using some science? I can not make sense of what you are trying to explain.
  14. Damorbel - still havent got a yes/no to #752. Are you prepared to have nature be the arbitrator?
  15. Phil 754
    "No-one believes the cold atmosphere warms the warmer earth. The Greenhouse effect slows the rate at which heat escapes from the earth. Period. "

    Earths blackbody temperature is 255K. This represents the theoretical maximum attainable temperature via the suns radiation. Kirchhoff's cavity experiment and subsequent law and Planks law were both derived by this pressies. So regardless of re-radiation and reflection, the atmosphere can NOT warm the warmer Earth...Period. Yet GHG proponents claim slowing the rate at which heat escapes the 255K earth some how warms the earth surface to 288K. So Phil, how does a body at 255K which is loosing heat increase it's temperature simply by slowing it's cooling....remember blackbody temperature is the theoretical maximum temp.
  16. damorbel

    Your lecture over the distinction between watts and Joules explains nothing; if I shine a 100 watt light bulb on your lecture notes, each second requires 100 Joules of electrical energy. If that energy is constrained from leaving the immediate environment by whatever means, the environment, including your lecture, heats up. If I direct a 125 milliWatt laser pointer on the wick of a candle in the vicinity of those notes, I can quickly set them aflame.

    Those applications are radiation effects. Your gravitational heating was ably dismissed on a number of occasions; the most recent by Tom C. No one is buying this brand of soap today.
  17. LJ Ryan: "regardless of re-radiation and reflection, the atmosphere can NOT warm the warmer Earth...Period."

    So the world you live in has an average temperature of -18C? How's that working out?

    Or did you forget that the blackbody 'theoretical maximum' you cling to refers to an object in equilibrium? Do you suggest that is the case for the earth? If so, do you not recall that we have an atmosphere, which traps energy that would otherwise escape?

    Even died-in-the-wool deniers accept that much.

    It is tedious to hear these repetitious 'objections' to basic physics that should be well-understood by now. Read and learn, my friend. If nothing else, the quality of your questions will improve.
  18. Tedious indeed. If you got past the idea that the atmosphere is warming the planet and bothered to learn how the GHE effects, then you would get some progress. Remember nature is the atmosphere. Your version of physics doesnt account for the observed world. The textbook version does. Is that a hint?
  19. damorbel (RE: 755),

    "And why the 'GH' effect is not a radiation effect... from... GH gases."

    OK, then what is the primary mechanism for the greenhouse effect?

    "No amount of refocussing etc., etc., of photons from a cold (255K) source, like the upper troposphere, can produce a temperature higher than 255K... anywhere.

    It's the photons you see, they don't have enough energy.

    They may have all the power (W/m^2) you can imagine* but no amount of refocussing, adding together, accummulating in reflecting cavities etc., etc. will raise their energy. Or, in other words, increase the temperature of.... anything. That is what the 2nd law is all about."


    Not really. The second law primarily states that heat can only flow from warm to cold - not the other way around. The atmosphere is largely transparent to the energy coming in from the Sun. The bottom line is the rate the incoming energy can leave the system from the surface is slower than the rate it is coming into the surface.

    The effect in principle is not much different than
    the interior of a car heating up inside on cold day from sitting out in the Sun. The Sun's energy is mostly transparent through the windows. It's then absorbed and re-radiated by the interior car components. The rate at which the energy is entering the interior is faster than the rate the re-radiated energy can leave the interior; therefore, the interior has to heat up.

    Ultimately, when the rate of energy entering something is faster than rate it can leave, the something has to heat up. That's the GHE.
  20. L.J. Ryan - "Earths blackbody temperature is 255K. This represents the theoretical maximum attainable temperature via the suns radiation."

    To be succinct - Bull - a completely unsupported statement. The surface of the Earth radiates at a temperature of 14C, or 287.15K, with an overall emissivity of 0.98. Upper layers of the troposphere (due to lapse rate) radiate at much higher altitudes, colder temperatures, rendering the planetary emissivity at ~0.612, regulating the amount of energy radiated at any temperature, and driving the surface temperature to the aforementioned 14C.

    Please - read some physics, get a clue. ---

    Folks, L.J.Ryan has shown either a complete lack of physics understanding, or a deliberate set of obfuscations. None of his objections has made sense. Damorbel is (in my opinion) a complete troll - he hasn't defended a single assertion, but keeps raising red herrings whenever pinned down, as he has done for over 4 months on this thread. He is now (as others have noted) circling back to previous disproved notions from several months ago, presented as fresh to people who have joined the thread.

    We are being trolled - do not feed the trolls.

    Moderators, John Cook - I'll join with previous posters; this cycle of denial and red herrings has gone on long enough. Are there any options in this regard? Perhaps deleting postings repeating junk from months ago? For some reason this particular thread attracts people who think that they either understand thermodynamics better than the previous 150 years of physicists, or perhaps feel that deliberate obfuscation and "common sense" arguments will draw out the discussion.

    16 pages, >770 posts, with every skeptic argument repeated multiple times. Gah...
    Response:

    [DB] "We are being trolled - do not feed the trolls."

    I will join you out on that limb.  Short of a comment directly violating the Comments Policy, what we can do is this: Merely repeating a previously expressed position without adding anything new is indeed grounds for moderation.  So if anyone notices a comment being lifted from a previous one without anything new being added, bring it to the Moderator's attention. 

    700+ posts is a lot; the Mods are human & can't be expected to remember each and every post.  So help each other out:

    1. DNFTT (no matter how much you want to, Do Not Engage)
    2. Be on the watch for recycled comments by those obviously clogging up the threads
    3. Let the Mods know when you see those recycled comments

    Trolls live for attention & generating controversy; deny them the pleasure.  Those that abuse the priviledge of participating in this community may lose that priviledge.

    Thanks for your time.

  21. KR, John Cook, Tom Curtis

    Please explain why, seriously, why Kirchhoff's cavity experiment does not represent the theoretical BB maximum temp.

    I realize it doesn't explain the 33K delta but why is wrong? Maybe your superior physics can explain how BB maximums should be determined.

    Don't insult me or say I'm wrong without explanation of what is wrong.
  22. "how does a body at 255K which is loosing heat increase it's temperature simply by slowing it's cooling....remember blackbody temperature is the theoretical maximum temp."

    Considering that the body in question is continuously receiving energy at a more or less constant rate, it does not seem so difficult to imagine that its temperature will increase if the rate at which it can radiate that energy is decreased. In fact, I would have a hard time to understand if it did not warm up under these conditions.
  23. L.J. Ryan - Blackbody temperature is important as a theoretic limit. However, the Earth in the real universe is not a blackbody. The Stefan-Boltzmann relationship holds for the Earth, and the power radiated to space (which must match power coming in for dynamic equilibrium) is determined by both the temperature and the emissivity of the planet.

    Any body that is not a blackbody (with an emissivity < 1.0) must have a higher temperature to radiate the same power as that blackbody. The blackbody is the theoretic best case; everything else is less efficient.

    With an effective (surface to space) emissivity of 0.612, including clouds, GHG's, tropospheric effects, lapse rates, etc., a surface temp of ~287 radiates ~239 W/m^2 to space, almost equal to the sunlight coming in. The difference of 0.9 W/m^2 is the forcing, heating the climate and moving back towards dynamic equilibrium.

    So - you are incorrect because the Earth is not a blackbody. It has a limited emissivity to space, and the resulting temperature needed to radiate 240 W/m^2 is around 14-15C.
  24. L.J. Ryan - From your reference: "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."

    And there is the error. The Earth is not a black body, but is a "gray body" with ~60% the emissive efficiency of a black body. And hence a higher temperature than a perfectly efficient black body radiator. Your reference is in quite serious error to argue against the greenhouse effect in these terms - it's a rather horrid miscasting of the situation. It's only an upper limit for a black body - anything with a lower emissivity will by necessity have a higher temperature for the same power output.

    I would not trust that source, given the example you presented.
  25. Sorry to break this into multiple posts - it's late and I'm tired.

    L.J. Ryan - Incoming energy is set by spectral absorptivity, albedo, and the spectra of the sun in visible light. Greenhouse gases have little effect on that - the most important elements there are ozone absorption and Rayleigh scattering.

    Given a fixed input energy, the black body temperature represents a minimum temperature for the radiating gray body, the Earth. Any lowering of emissivity (such as increasing greenhouse gases) must be balanced by an increase in temperature above that of the black body case to match input power.
  26. But Daniel, the thread has been instructive. Pretty much every kind of wiggle imaginable has been attempted. If anyone who has any doubt about GHGs and the 2nd law after reading the entirety of this thread, they should get some sleep and try it again in the morning. Or perhaps try a more thorough explanation of a pretty simple physical interaction.
    Response:

    [DB] Anyone with the willpower to read the entirety of this thread has a cast-iron stomach and a thing for pain. Maybe that's why I'm a mod. :)

    It should be painfully obvious by now that all that is being offered up are permutations of permutations (ad nauseum) of debunked and rebunked arguments.

  27. John and moderators, I agree. Despite DSL's point (valid to an extent), I can not see how allowing the same obfuscation again and again adds anything. Most readers who are unfamiliar with the physics would only take away the impression that this is a matter of debate and their perception of the whole process might be totally confused. Obfuscation is not useful to anyone.
  28. Philippe Chantreau

    "Most readers who are unfamiliar with the physics would only take away the impression that this is a matter of debate and their perception of the whole process might be totally confused. Obfuscation is not useful to anyone"

    Said otherwise:

    Quick kill the debate! Uncomfortable points of contention must not be seen!

    Back tomorrow, if this thread is still open.
    Response:

    [DB] Despite handwaving implications to the contrary, the existence and length of this thread is mute testimony to the tolerance of non-physical points of contention. On-topic comments constructed to comply with the Comments Policy go unmoderated, as the vast majority of readership here at Skeptical Science can attest.

    You have yet to demonstrate the physical-ness of your position, as other participants have pointed out to you several times.

  29. Nonsense and more obfuscation. Your accusation would be somewhat insulting if I cared the least about your opinion.

    If you want to debate atmospheric physics that are obvious to all researchers in the field, you should take it to the peer-reviewed litterature. I'll be very curious to see how your first paper looks like. What you are trying to argue about is no more a matter of debate than protein encoding by DNA. I have seen nothing of value for any kind of debate in the tediousness with which you have drowned this thread.
  30. Re 769 RW1damorbel (RE: 755),

    ""And why the 'GH' effect is not a radiation effect... from... GH gases."

    OK, then what is the primary mechanism for the greenhouse effect?"

    Since the GHE is an explained as a radiation effect t

    "No amount of refocussing ...... Or, in other words, increase the temperature of.... anything. That is what the 2nd law is all about."
    #Responding you say:-
    "The second law primarily states that heat can only flow from warm to cold - not the other way around."

    Yes

    However, you say also:-
    ".. the rate the incoming energy can leave the system from the surface is slower than the rate it is coming into the surface."

    Most GHE explanations say that this 'slowing' is because of a warming effect on the surface by radiation from GH gases in the atmosphere.

    Since the atmosphere is colder than the surface any radiation from it will not warm the surface because its photons do not have the energy to do this. What does happen is, photons from the surface, having more energy than photons in the upper atmosphere warm it, the heat thus transferred upwards is re-radiated (by GHGs) into deep space, keeping them cool. Do you agree?

    Then you write:-

    "The effect in principle is not much different than
    the interior of a car heating up inside on cold day from sitting out in the Sun. The Sun's energy is mostly transparent through the windows. It's then absorbed and re-radiated by the interior car components. The rate at which the energy is entering the interior is faster than the rate the re-radiated energy can leave the interior; therefore, the interior has to heat up."

    What you say doesn't just apply to a car, it is the same for a greenhouse or any surface exposed directly to the Sun's output. It's well known that, in a desert, the Sun can heat a surface well above 100C, enough to fry an egg.

    But even the arguments for the GH effect agree that it is the average temperature that is inportant, so they account for this by saying the Sun's output (the solar constant ) is not the measured 1370W/m^2 (@5780K if they include the temperature of the photons) but 342.5W/m^2 this latter would give an average temperature of about 279K, an average taken over the entire planet - summer and winter; pole to pole.

    Further you have:-

    "Ultimately, when the rate of energy entering something is faster than rate it can leave, the something has to heat up. That's the GHE."

    Couldn't agree more. Are you able to say at what temperature this would stop, if at all?

    The only beef I have with the arguments for the existance of the GHE is that it is not supported by well established thermal physics, like focussing photons increases their energy, simply not true. If it were true mirrors would change the colour of light when they reflect it; now that would be strange!
    Response:

    [DB] "The only beef I have with the arguments for the existance of the GHE is that it is not supported by well established thermal physics"

    Then you haven't been paying attention, clearly. Read the whole post, starting at the beginning. The comments too, if necessary.

  31. Re #780 it has :-

    "an average temperature of about 279K, an average taken over the entire planet - summer and winter; pole to pole."

    And of course, 'day and night'.
  32. Damorbel - still waiting to hear whether you accept that experiment is way to settle the debate. Sounds like you only want to talk, not find anything out.
  33. Re #782 scaddenp you wrote:-

    "still waiting to hear whether you accept that experiment is way to settle the debate."

    Not at all sure what experiment you have in mind. Care to describe it?
    Response: [DB] The question here, which you have conspicuously avoided answering for some time now, makes it clear that the experiment design to prove your alternative world of physics is up to you. We're still waiting.
  34. Re #783 damorbel - & Response: [DB]

    DB I am deeply dissappointed to have to write this, since my capabilities are definitely 'off topic' and it might be thought that some of the remarks in the cited link are 'ad hominem'.

    Your link has this :-

    "I didnt describe any experiment."

    You must forgive me, I was looking to you to describe an experiment to which I could agree.

    Next in the link it has:-
    I proposed that an experiment be designed such that normal understanding of physics and your understanding would calculate a different result."

    This of course doesn't mean I am abnormal.

    Then the link has:-
    "This is normal way to test scientific arguments."

    I'm afraid I do not quite understand what this means, does it also mean that I cannot achieve a scientific result?

    And:-
    "I asked if the experiment didn't go your way,"

    As yet no experiment to 'go my way'

    Further in the link:-
    "whether you would be prepared to abandon your view and read the textbook. (ie, behave like a scientist)

    Interesting question. But I don't know which textbook I am suppose to read or whether it is a requirement for scientists to read text books. Personally I recommend original works, textbook contents are at least 2nd hand if not much more; at university my tutors always advised original texts, they had a low opinion of published textbooks.

    Finally:-

    "Got a yes/no? In fact, have you got an experiment that you think validates your views over mainstream physics?"

    I have set out clearly what the essence of how energy is transferred by means of photons and so far nobody has shown it to be incorrect.
    Response: [muoncounter] We've heard the one about textbooks before. No need recycling your old ideas when they didn't work first time around.
  35. 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.

    In short. You give every appearance of knowing that your argument is groundless and not even trying to defend it... save by obfuscating with trivialities;

    Like using a solar cooker to cool something. Which really applies the same principle in reverse. Infrared energy coming off the object inside the cooker is reflected away towards open space. Provided the cooker is insulated enough to limit IR coming in from other directions and the IR input from the area it is pointed towards is less than the IR being reflected away from the object you get a net cooling effect. This proves that energy can flow from warmer areas to cooler ones... just as using the cooker/parabolic mirror during the day proves that energy can also flow from cooler areas (the mirrored surface) to warmer areas (the heated object at the focal point).

    damorbel: I thought your arguments were too ridiculous to be actually believed back when you were just arguing things like 'the reflectivity of an object has no impact on its temperature' and 'electromagnetic waves can only travel from cold areas to warmer areas in large bandwidths'. Now that you've moved on to 'the greenhouse effect is caused by gravity' and the like we clearly live in universes too profoundly different to allow any sort of rational discussion.
  36. Damorbel @780, One last chance:

    Most GHE explanations say that this 'slowing' is because of a warming effect on the surface by radiation from GH gases in the atmosphere.

    Since the atmosphere is colder than the surface any radiation from it will not warm the surface because its photons do not have the energy to do this. What does happen is, photons from the surface, having more energy than photons in the upper atmosphere warm it, the heat thus transferred upwards is re-radiated (by GHGs) into deep space, keeping them cool. Do you agree?


    1) The Green House Gases in the atmosphere undoubtedly radiate in all directions as, a) this is the predicted behaviour in theory of radiation; and b) the radiation from those gases have been observed from space, and from high flying planes lookding down; and from the ground and from low flying planes looking up. An example of one such measurement is found in the intermediate version of the above article. So, as a matter of empirical fact, IR radiation is emitted by GHG in the downward direction.

    2) The surface of the Earth has a very high emissivity and hence absorptivity in the wavelengths in which IR radiation is emitted by Green House Gases. This is shown very clearly (from observation) in post 703 by Alexander above. Note, the wavelength of peak emission by CO2 is 15 microns, with the "wings" of peak emission extending from 13 to 17 microns thus showing significant overlap with every type of surface shown, except coarse snow, which of course significantly overlaps with H2O emissions. Thus, over land, the vast majority of Downward Long Wave Radiation is absorbed by the surface, and at sea a significant proportion of it, in most cases the majority of it is absorbed.

    3) If a photon is absorbed by a surface, the surface gains the energy that was contained in the photon (by conservation of energy).

    4) If energy is absorbed by a surface, all else being equal, the temperature of the surface will rise, and the surface is warmed.

    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.

    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.

    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.

    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.

    9) Of course, the Earth's surface is periodically warmed by a very bright energy source, the Sun. For most locations on Earth, the period it is warmed is for on average 12 hours out of every 24.

    10) The amount of energy received from the Sun in any 24 hour period at any location is (to a first approximation) not a function of the temperature at that location. Therefore, the Earth at any location will be warmer if it cools less at night because it will add the Sun's energy received that day to a higher base level.

    11) Therefore, because GHG slow cooling, they result in warmer temperatures on the surface of the Earth, not because they are by themselves capable of providing a net warming to the Earth, but because they slow the loss of the energy provided by the Sun.

    (12) This does not explain the equilibrium temperature of the Earth's surface, which is governed by the need for the Outgoing Infrared Radiation to balance the Incoming Short Wave Radiation, which balance is achieved by the interplay of upper tropospheric temperatures and surface temperatures brought about by the lapse rate and GHG concentrations.

    Each of (1) through (12) above is straight forward, blindingly obvious, and well confirmed by by being predicted by basic physical laws, and by being observed multiple times. Jointly, they refute your entire case.

    I am not entering into a discussion on this point out of deference to the moderators request that we not feed the trolls. However, laid out step by step like this, even you, Damorbel, should be able to see what absolute drivel you have been serving up.
  37. Damorbel: "Since the atmosphere is colder than the surface any radiation from it will not warm the surface because its photons do not have the energy to do this. What does happen is, photons from the surface, having more energy than photons in the upper atmosphere warm it, the heat thus transferred upwards is re-radiated (by GHGs) into deep space, keeping them cool. Do you agree?"

    So you're saying that the photons emitted by the atmosphere are only emitted away from the surface. No photon could possibly be emitted toward the surface, because the surface is warmer. Do you agree?
  38. Re #785 DB you wrote:-

    "This proves that energy can flow from warmer areas to cooler ones... "

    The basic 2nd Law.

    Further you wrote:-

    "just as using the cooker/parabolic mirror during the day proves that energy can also flow from cooler areas (the mirrored surface) to warmer areas (the heated object at the focal point)."

    When a mirror focusses the Suns image on the food you are saying... that the energy comes from the ....mirror?

    Ahem, CBD I think this is not right. Doesn't the energy come from the Sun and is just redirected by the mirror?

    A mirror is about as far from a black body as it is possible to get, it doesn't absorb radiation. A mirror's temperature is not changed by incident radiation because it is reflected without being absorbed; that is why a mirror is used to block radiation to and from a vacuum flask.

    Likewise mirrors do not emit radiation; you claim that heat (in a solar cooker) 'goes from the mirror' but the temperature of a mirror is not changed when the sun shines on it, only the food is cooked!
  39. Re #787 DSL you wrote:-

    "you're saying that the photons emitted by the atmosphere are only emitted away from the surface. "

    No, I didn't say that. The photons emitted downwards have lower energy than those at the surface so there is no warming of the surface, it is the emitting gases in the upper atmosphere that are warmed by by the (more energetic) photons emitted by the surface.

    And further you wrote:-

    "No photon could possibly be emitted toward the surface, because the surface is warmer. Do you agree?"

    No I don't agree. See the first answer.
  40. Damorbel: "No, I didn't say that. The photons emitted downwards have lower energy than those at the surface so there is no warming of the surface, it is the emitting gases in the upper atmosphere that are warmed by by the (more energetic) photons emitted by the surface."

    So the natural question, then, is "what happens to these lower-energy photons?" Are they or are they not absorbed by the surface? If not, what happens to them?
  41. Damorbel: "Doesn't the energy come from the Sun and is just redirected by the mirror?"

    Irrelevant gibber-gabber. The source of the radiation does not change its behavior, but even if it did... the energy being redirected by the greenhouse gases 'came from the Sun' too.

    The object at the focal point of the parabolic mirror is warmer than the air around it, which is in turn warmer than the mirror. Yet energy moves through space from the cold mirror to the warmer air to the warmer still object. This is exactly what you claim violates the 2nd (and/or 1st) law of thermodynamics when greenhouse gases do it. So how is this commonly observed phenomena possible? It violates what you claim to be a fundamental law of physics, but it is observed reality. Ergo... your claims about thermodynamic laws must be false.
  42. DSL 760

    "The reflective surface focuses incoming radiation." --yes, solar radiation when cooking.

    "That radiation could be coming from the atmosphere." ---from the sun for cooking...that is how it works. If you point away from the sun the target COOLS below ambient temperature.

    "Your argument is that we can't differentiate between radiative transfer and conduction/convective transfer." ---I'm not sure what you mean.

    "In other words, why doesn't the solar cooker cool to near absolute zero when pointed at the open night sky?" ---It fact, it's temp. drops well below ambient. However the atmosphere, as you know, is not absolute zero. Thus potential drop is limited by atmos. temp. and the rate of drop is determined by delta T between cooker contents and the sky. If the atmosphere is same temp as the cooker no cooling occurs. If the atmosphere is warmer then the cooker, the contents warm.
  43. CBDunkerson 785

    "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."

    Where/when did I say this?
  44. Philippe Chantreau 772

    "Considering that the body in question is continuously receiving energy at a more or less constant rate, it does not seem so difficult to imagine that its temperature will increase if the rate at which it can radiate that energy is decreased. In fact, I would have a hard time to understand if it did not warm up under these conditions. "

    Philippe, blackbody radiation is based upon a "constant rate". Adding more radiation of less magnitude does NOT change the output. Adding more radiation of the same magnitude does NOT change output. Adding more radiation of higher magnitude DOES change the output.

    Do you agree?

    Any interested readers should note your evasion, and that you do not feel confident enough to discuss the case on its merits.
  45. KR 773-775

    A bit sleight of hand KR. Power input is also based on emissivity. Lower emissivity, higher reflectivity, thus less power input. Lower "fixed" input lower base temp i.e. lower then 255K. So GHG effect must account for more then 33K. Said differently, a body does not absorb one emissivity and radiate at another.

    Regarding the Alan Siddon post, neither he nor I believe earth is a blackbody. The gist of the post, blackbody represent max radiation input and max output. Regardless of reflection and re-radiation, max radiation output cannot be exceeded less higher energy input. Very simple concept, proven by years of actual data measurements.

    Do you agree?
  46. DB

    "You have yet to demonstrate the physical-ness of your position, as other participants have pointed out to you several times."

    Physical-ness of MY argument. Yet you proponents contradict one another when TRYING to explain the lack of "physical-ness" of my contentions. You press for answer on behalf of whom you agree. Yet chastise skeptics for re-posting question which remain unanswered.
  47. You can't formulate anything in a coherent fashion. You're the one evading my question with irrelevant gibberish.

    I am not talking about adding radiation of any magnitude, whatever that means. 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?

    About this:
    "it's temp. drops well below ambient"
    How does it square with this? "If the atmosphere is same temp as the cooker no cooling occurs." It drops below "ambient" but then if the temp is the same as the ambient atmosphere, no cooling occurs? More incoherence and more nonsense.
    Response: Let's end the sniping here, there is nothing constructive coming from it.
  48. LJ,

    Please clarify your statements where you say "Adding more radiation of the same magnitude does NOT change output". What precisely do you mean by "more" radiation of the same "magnitude"? By magnitude are you referring to the frequency of the radiation?

    Let's say we have an object in a vacuum absorbing one photon per second with a wavelength of 1um for all photons. If we increase the rate of incident energy to two photons per second, but they all remain at a wavelength of 1um, are you saying the amount of radiation emitted by the object does not change?
  49. LJR: "neither he nor I believe earth is a blackbody."

    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).

    As far as 'fundamental flaws' (#797), you haven't proven them; a reference to someone else's blog and 'google solar cooker' do not cut it as scientific source material.
  50. Me: "In other words, why doesn't the solar cooker cool to near absolute zero when pointed at the open night sky?"

    LJ Ryan: It fact, it's temp. drops well below ambient. However the atmosphere, as you know, is not absolute zero. Thus potential drop is limited by atmos. temp. and the rate of drop is determined by delta T between cooker contents and the sky. If the atmosphere is same temp as the cooker no cooling occurs. If the atmosphere is warmer then the cooker, the contents warm.

    Or, rather, if the cooker is radiating energy at the same rate that the atmosphere is radiating at it (removing conducted energy from the equation), then the cooker will remain at the same temperature. If the atmosphere is not adding radiated energy to the cooker, the cooker--if unable to shed via conduction (e.g., in a vacuum box)--will cool to near absolute zero when pointed at the night sky. But, of course, all atmospheric layers do radiate, and some of this radiation is absorbed by warmer surfaces and warmer atmospheric layers. 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.

    That the atmosphere doesn't heat the surface or warmer atmospheric layers is false. The heating is already taking place, and the result is the equilibrium temp. It's a mistake to think that this equilibrium temp is a baseline temp to which atmospheric energy is added. If we increase the radiative density of the atmosphere, the radiation has a greater chance of being redirected (in all directions). The maze is more complex, the pachinko machine has more pins, the dam is higher, etc. etc. The amount of available, usable energy in the lower layers increases because it's around longer in those layers.

    Do I have this right?

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