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Can a blanket violate the second law of thermodynamics?

Filed under: — stefan @ 20 September 2016

One of the silliest arguments of climate deniers goes like this: the atmosphere with its greenhouse gases cannot warm the Earth’s surface, because it is colder than the surface. But heat always flows from warm to cold and never vice versa, as stated in the second law of thermodynamics.

The freshly baked Australian Senator Malcolm Roberts has recently phrased it thus in his maiden speech:

It is basic. The sun warms the earth’s surface. The surface, by contact, warms the moving, circulating atmosphere. That means the atmosphere cools the surface. How then can the atmosphere warm it? It cannot. That is why their computer models are wrong.

This is of course not only questions the increasing human-caused greenhouse effect, but in general our understanding of temperatures on all planets, which goes back to Joseph Fourier, who in 1824 was the first to understand the importance of the greenhouse effect.

The atmosphere acts like a blanket which inhibits heat loss. In fact according to Roberts’ logic, a blanket could also not have a warming effect:

It’s simple. The body warms the blanket. This means that the blanket cools the body. So how can the blanket warm it? It cannot!

The answer is simple. The warm body loses heat to the cold air. The blanket inhibits and slows this heat loss. Therefore you stay warmer under a blanket.

The Earth loses heat to the cold universe. The atmosphere inhibits this heat loss. Therefore, the surface remains warmer than it would be without the atmosphere.

It is true that the surface loses heat to the atmosphere – but less than it would otherwise lose directly to space. Just as I lose less heat to the blanket than I would otherwise lose to the air, without blanket.

Of course, in neither case is the second law of thermodynamics violated. The heat always flows from warm to cold – just more or less effectively. The processes of heat transfer are quite different – for the blanket it is mainly heat conduction, for the greenhouse effect it is thermal radiation. The climate deniers claim that the colder atmosphere cannot radiate thermal radiation towards the warmer surface. This is of course nonsense. The cool Earth also sends thermal radiation towards the hot sun – how would thermal radiation leaving Earth know how warm the surface is that it’s going to hit? It’s just that the sun sends more radiation back to us  – the net flow is from hot to cold. More is not implied by the second law of thermodynamics.

Thanks to two Germans (Gerlich and Tscheuschner of the TU Braunscheig – deeply embarrassing for this university), the absurd claim that the greenhouse effect violates the second law of thermodynamics even made it into an obscure physics journal – obviously there was no peer review to speak of. The bizarre article was promptly demolished by some US physicists. Just recently I read the claim again in an article of coal lobbyist Lars Schernikau – with such fairy-tale beliefs of its representatives, one is not surprised by the decline of the coal industry.

The thermal radiation from the atmosphere toward the ground, which allegedly cannot exist, is of course routinely measured, including its increase (see e.g. Philipona et al. 2004, 2012).

And you can even feel it. Those who sometimes sit outside in the garden after dark know this. Under a dense, low cloud layer you do not nearly get cold as fast as on a clear starry night. This is due to the thermal radiation coming from the clouds. They are colder than our body, but warmer than the night sky in clear air.

Roberts said: “Like Socrates, I love asking questions to get to the truth.”  Perhaps he will ponder my answer next time he sits in his garden at night, or slips under a blanket.

P.S.

Here is the energy balance diagram for our Earth, explained in IPCC FAQ 1.1. The “Back Radiation” makes the greenhouse effect. It is larger than the solar radiation reaching the ground, and measured by a global radiation measurement network.

faq-1-1-figure-1

References

R. Philipona, “Radiative forcing – measured at Earth’s surface – corroborate the increasing greenhouse effect”, Geophys. Res. Lett., vol. 31, 2004. http://dx.doi.org/10.1029/2003GL018765

R. Philipona, A. Kräuchi, and E. Brocard, “Solar and thermal radiation profiles and radiative forcing measured through the atmosphere”, Geophys. Res. Lett., vol. 39, pp. n/a-n/a, 2012. http://dx.doi.org/10.1029/2012GL052087

229 Responses to “Can a blanket violate the second law of thermodynamics?”

  1. 51

    M 47: you’ve also got 324w/sq.m. ,belting down from the ATMOSPHERE 24/7. !!!?

    BPL: Yes. Use the Stefan-Boltzmann law. Find out what Earth’s surface temperature would be with 161 Watts per square meter sunlight alone. Then try it with that plus the atmospheric back-radiation. See what you get. Remember, T = (F / sb) ^ 0.25 where sb is the Stefan-Boltzmann constant.

  2. 52
    Joe Cushley says:

    Thomas #48

    If you think Tony Blair is a Lefty, you really don’t know much about UK politics…

  3. 53
    Paul Donahue says:

    #39 Hank R.

    Yes, but doesn’t color correspond to emissivity? Paint a roof white using any kind of paint, and it will heat less in daytime, and become less cool at night.

  4. 54
    Jim Eager says:

    For Mack @47: That 324 w/sq m from the atmosphere is the reason earth’s global mean temperature is 15C instead of -18C. In other words, you’ve just put your finger on the greenhouse effect.

  5. 55
    Alfred Jones says:

    Mack, it’s kinda the same bit of logic that deniers miss when it comes to the importance of man’s CO2 emissions as compared to natural emissions. You have to include both inflow and outflow. The issue is net, not gross.

    Painting the sun as the “unnatural” actor, we find that about 450 w are naturally emitted from the surface (your 350 plus thermals and evaporation) and 324 w are absorbed. Thus, “naturally” the planet will steadily cool.

    Then we add in the “unnatural” sun. Like human CO2 emissions are to atmospheric concentration of CO2, the sun’s energy emissions shove the daylight side of the planet enough so there’s a net warming. (And you have to double the solar numbers if you want intensity, since they are concentrated onto half the planet’s surface. Plus, the energy is further concentrated based on the receiver’s orientation. Turn your back, and your face is no longer warmed. Cooling is based on total surface area while warming/tanning is generally less than the area of a perpendicular plane.)

  6. 56
    Alfred Jones says:

    Andrew Dodds: I’m trying to coax them into my car engine so I can get negative MPG.

    AJ: If you want negative MPG, just drive in reverse!

    BTAIM, some super-cooling devices use a process similar to Maxwell’s demon. The put atoms in a cup and let them bounce around. Only the fastest leap high enough to escape. Demonically clever, eh?

  7. 57
    Titus says:

    I don’t find the blanket analogy fits my understanding very well.
    When I think of a blanket its what I use to keep me warm at night. The only reason I’m warm is that I’m producing heat, the blanket keeps that heat from escaping into the air around me.
    If I were to die I would not be producing heat and the blanket would stop heat from coming in. Therefore I end up a cold corpse.
    So it’s my heat that keeps me warm (except of course for a bit of passing through the insulation of the blanket)
    My two cents worth….

  8. 58
    Keith Woollard says:

    Vendicar @ 43
    “Satellites don’t measure temperature, but measure some integrated signal that is emitted by the whole atmosphere and which must be heavily modified in order to extract an approximation of the temperature of thick swaths of atmosphere.”

    Thermometers don’t measure temperature, they measure electrical resistance and the value is converted to a temperature at one point in space is then applied to a huge spatial area

  9. 59
    Eli Rabett says:

    One of the simplest refutations of such nonsense is how halogen lamps are improved by putting a thin IR reflecting dielectric mirror on the inside of the glass envelope. The IR component of the light from the filament is reflected back and heats the filament further resulting in more visible light being emitted. The IR coating improves efficiency by about 40% making the visible output of a 60 watt bulb equivalent to that of a 90.

    Eli did about the same thing many years ago by putting a thin foil of aluminum around a light bulb which resulted in a strong warming of the outside of the lamp, and, of course, a survival blanket, a think aluminized piece of plastic will keep everybunny warm and toasty.

  10. 60
    Thomas says:

    53 Joe Cushley, it was a joke billy, for an American audience. To 99% of American’s he’d be a raving socialist 10 times worse than Bernie Sanders.

    You take jokes pretty seriously do you? They are not supposed to not be ‘logical’ or ‘literally true’ because if they were they wouldn’t be a ‘joke’, would they? (sigh)

    Now having to explain a joke, kinda kills it as well. Thanks for that.

  11. 61
    Thomas says:

    59 Keith Woollard says: “Thermometers don’t measure temperature, they measure electrical resistance and the value is converted to a temperature at one point in space is then applied to a huge spatial area”

    Keith fyi from the prehistoric dark ages
    http://www.clipartkid.com/images/481/classic-thermometer-royalty-free-stock-photography-image-10466137-5VcV1J-clipart.jpg

    (smile)

  12. 62
    Chris O'Neill says:

    Keith Woollard #59:

    Thermometers don’t measure temperature

    At least thermometers on the surface are themselves pretty much at the temperature they are trying to measure and bound to it by thermal conduction.

    We can’t say the same things for satellites hundreds of kilometres above the atmosphere.

  13. 63
    Silk says:

    #62 – Careful! We’ll end up having to have an article called “Can a thermometer violate the zeroth law of thermodynamics?”

    And then Victor will come along and tell us that there’s no such thing as the zeroth law, as “zeroth” isn’t a word.

  14. 64

    Paul Donohue, #53–“Yes, but doesn’t color correspond to emissivity?”

    Only partially true. Color corresponds to emissivity *in visible frequencies*. IR results may vary…

  15. 65

    Titus, #54–

    Correct. Your body heat corresponds in the analogy to the heat produced at the Earth’s surface (mostly, if you get fussy there’s heating in that atmosphere as well) by solar radiation.

  16. 66
    Mack says:

    Jim Eager @54
    “That 324w/sq.m. from the atmosphere is the reason earth’s global mean temp is 15C instead of -18C.”
    Hell Jim, earth’s global mean temp of -18C would have the earth as one FROZEN ball….even the oceans would be frozen solid. Are you seriously telling me that radiation from the atmosphere..or some atmospheric effect, is actually keeping the whole planet from totally freezing up !!?. I always thought it was the sun that melted ice.

    [Response: This was the mystery that Fourier thought a lot about in 19th Century. Turns out it is an atmospheric effect. Pretty well accepted now though. – gavin]

  17. 67
    Eli Rabett says:

    #53 Thermometry is, of course, interesting technology.

    The first technology measured the expansion of liquid (mercury, alcohol, etc) in a reservoir expanding into a small capillary tube.

    Then there are thermocouples which measure a voltage produced at the interface between two metals that is proportional to temperature.

    Then there are (platinum) resistance thermometers which measure the change in resistance with temperature

    Then there are the (advanced) microwave sounding units used to infer temperature from microwave emissions in the atmosphere. These are basically tuned antennas measuring the emission in very narrow bands of the microwave spectrum whose intensity is proportional to temperature.

  18. 68
    zebra says:

    For Paul Donohue at #53, and also others:

    It’s complicated.

    From Wikipedia:

    With the exception of bare, polished metals, the appearance of a surface to the eye is not a good guide to emissivities near room temperature. Thus white paint absorbs very little visible light. However, at an infrared wavelength of 10×10−6 meters, paint absorbs light very well, and has a high emissivity. Similarly, pure water absorbs very little visible light, but water is nonetheless a strong infrared absorber and has a correspondingly high emissivity.

    My more general observation for many comments: It’s complicated, and trying to find colloquial language and analogies that you think will make it all clear is a fools game.

    Have a little faith in your “students”, and be rigorous and organized and use formal language. “X ‘warms’ Y” doesn’t qualify. If someone is sincere and interested in understanding, she will ask questions. (Of course, you must be prepared to answer them.)

  19. 69
    Jeffrey Davis says:

    If the atmosphere couldn’t keep the planet warm, neither could a blanket or coat keep a body warm, insulation keep a house warm, and on and on. Nobody who makes those arguments lives without clothes or out in the open.

  20. 70
    Jim Eager says:

    Mack @66: “Are you seriously telling me that radiation from the atmosphere..or some atmospheric effect, is actually keeping the whole planet from totally freezing up !!?

    Yes, Mack, that is exactly what I’m telling you.

    It’s hardly news, Joseph Fourier first calculated it in 1824. It’s basic earth science based on the amount of sunlight reaching the top of earth’s atmosphere (1350 w/m^2), earth’s reflectivity or albedo (.33), and earth’s cross section area integrated over earth’s surface area. See Surface temperature of a planet down the Effective temperature wiki page at
    https://en.wikipedia.org/wiki/Effective_temperature

  21. 71
    Hank Roberts says:

    > Paul Donohue … but doesn’t …?

    Only for a “black body” continuous spectrum source.
    If you slowly heat a chunk of iron (or a sufficiently large ball of hydrogen), it does go through color changes corresponding to temperature.

    It’s a very common confusion (confused by (among others) streetlight vendors who are eager to sell cheap LED lights with a large blue emission spike in the spectrum but a “warm white” color temperature by also boosting the red end phosphors).

    Color temperature is what you, as a human with normal color vision, will perceive.
    A dog or a honeybee sees a different ‘color temperature’

    The emissivity of the surface of a material is its effectiveness in emitting energy as thermal radiation.

    Black cast iron skillet — high emissivity
    Shiny stainless steel skillet — low emissivity

    This may help: http://lowel.tiffen.com/edu/color_temperature_and_rendering_demystified.html

    To bring it back to topic: what the ‘niers miss is that the visible light carries energy through the atmosphere.

    Lie down outdoors while the sun shines; your blanket will warm up, whether you’re alive or not.

    The visible light hits the blanket, ground or water, transfers that energy to the solid or liquid (which being solid or liquid shares that energy with what surrounds it, warming up.

    The soil and water warm up and emit – infrared, and water and CO2 and other gases in the atmosphere do interact with some of the infrared, capturing some of that energy and re-radiating it in all directions, up sideways and down.

  22. 72
    Windchasers says:

    “Thermometers don’t measure temperature, they measure electrical resistance and the value is converted to a temperature at one point in space is then applied to a huge spatial area”

    Ayep. But thermometers’ measurements are much more accurate than the satellite measurements. That’s really what matters.

    Thermometers are at least measuring the local conditions. Satellites measure the light coming from an entire column of air in the atmosphere, and then have to tease out the temperature signal. Which would be doable with enough data, but generally we only have one satellite up at a time, and they suffer from calibration issues.

  23. 73

    M 66: Are you seriously telling me that radiation from the atmosphere..or some atmospheric effect, is actually keeping the whole planet from totally freezing up !!?

    BPL: Yes, that’s exactly what we’re telling you. Without the greenhouse gases in Earth’s atmosphere, it would be frozen over. Sunlight alone is not enough to keep the Earth habitable at its orbital distance.

  24. 74
    Vendicar Decarian says:

    58 -“Thermometers don’t measure temperature, they measure electrical resistance”

    Depends on the thermometer. Most thermometers measure the volumetric expansion of alcohol or mercury which is what is ultimately the historically how temperature has been DEFINED.

    Subsequent re-definitions of Temperature are subservient to the original due to the need for backward compatibility.

    Satellites on the other hand, in no way measure temperature. It is only through significant mathematical analysis and modeling of the signal they receive, that the signal can be de-convoluted into something that is claimed to be a temperature, although averaged over miles thick layers of atmosphere.

  25. 75
    Mack says:

    Jim Eager @70
    …. ” Joseph Fourier first calculated it in 1824. It’s basic earth science based on the amount of sunlight reaching the top of the earth’s atmosphere (1350 w/sq.m.)…”
    Hang on Jim, if you look at Trenberth’s Earth Energy Budget diagram, he shows 342w/sq.m. solar radiation arriving at the top of the earth’s atmosphere. I’m confused a bit here. Does Trenberth, (and this “basic earth science” calculation by Fourier…and perpetuated by all the institutes of earth science)have the correct amount of solar radiation arriving at the TOA, (top of the earth’s atmosphere) ??
    Actually, I think not, satellites sit out at the edge of space (TOA) and record the incoming solar 24/7 …as you know..the sun never sets in space…and space is right there..at the TOA.
    Besides this, some of these newer outer satellites, look back toward earth and observe, in the thermosphere, the actual glowing with heat, of CO2 and waste nitric oxides, irradiated by the sun. Also..mind you..Fourier would have no idea about a thermosphere back in 1824.
    So who do you think is right, Jim? about the amount of solar radiation arriving at the TOA. Do you think Fourier and Trenberth are correct at a calculation of 340w/sq.m. shown in the earth energy budget diagrams…or is it 1360w/sq.m. measured 24/7 and accurately by the satellites ?

  26. 76

    #73, BPL–

    M 66: Are you seriously telling me that radiation from the atmosphere..or some atmospheric effect, is actually keeping the whole planet from totally freezing up !!?

    BPL: Yes, that’s exactly what we’re telling you. Without the greenhouse gases in Earth’s atmosphere, it would be frozen over. Sunlight alone is not enough to keep the Earth habitable at its orbital distance.

    Indeed. A pretty good point of evidence on this topic is the Moon:

    Temperatures on the moon are extreme, ranging from boiling hot to freezing cold depending on where the sun is shining. There is no significant atmosphere on the moon, so it cannot trap heat or insulate the surface.

    The moon rotates on its axis in about 27 days. Daytime on one side of the moon lasts about 13 and a half days, followed by 13 and a half nights of darkness. When sunlight hits the moon’s surface, the temperature can reach 253 degrees F (123 C). The “dark side of the moon” can have temperatures dipping to minus 243 F (minus 153 C).

    …there are places at the lunar poles that never see daylight. The Lunar Reconnaissance Orbiter measured temperatures of minus 396 F (minus 238 C) in craters at the southern pole and minus 413 F (minus 247 C) in a crater at the northern pole. That is the coldest temperature ever recorded in the solar system, colder even than Pluto.

    The mean temperature of the lunar surface is given as 220 K, which is -53.15 C, though in most ways that’s not a hugely helpful measure given the drastic variability. But it does go to the importance of an atmosphere in distributing heat in general, and to the importance of a greenhouse effect specifically. Interesting in this connection is that the mean surface temperature of Mars is approximately the same as that of the Moon– -55 C is a common value–although Mars is 50% farther from the Sun than is the Earth-Moon pair. Mars has a thin but CO2-rich atmosphere, and a significant greenhouse effect.

    Novel (for me) factoid: there is a climate model for Mars, the MGCM.

    https://en.wikipedia.org/wiki/Climate_of_Mars#Temperature

  27. 77
    Titus says:

    @65 Kevin McKinney. Thanks for confirmation of agreement.

    This opens up a huge issue in as much that the blanket analogy only works on the release of heat from the earths surface (as you appear to agree). However, the earth needs to be heated in the first place which a blanket would restrict. E.g. The reason for covering ourselves in hot deserts.

    So, the blanket analogy causes thinking folks to question because it doesn’t fit their understanding of a blanket or how the atmosphere works. So I suggest it needs to be removed from the model/concept.

  28. 78
    Silk says:

    #66 – Let’s be clear here. There is no “radiation from the atmosphere”, in that the atmosphere isn’t /generating/ radiation.

    There is radiation from the sun which lands on the earth. The earth radiates out into space. The effect of the atmosphere is to insulate the earth, such that the equilibrium temperature of the earth’s surface is higher than it would have been.

    The analogy of a blanket is a good one. The analogy of a heated house an even better one. Close the windows. Turn on your boiler and all your radiators, full blast. Measure the temperature. Now insulate the house (or just close the curtains). Measure the temperature. It’s higher, not because the insulation (or curtains) generate any energy, but because insulation impedes the loss of heat, which means the house warms up until it reaches a new equilibrium temperature.

    The boiler is the sun, in this analogy. It supplies the energy. The house is the earth. Better insulation/closed curtains doesn’t change the amount of energy that the house loses, at equilibrium. At equlibrium energy in equals energy out. But to reach equilibrium in a better insulated house, for the same rate of energy input (power) the temperature must be higher.

    Does that make sense?

  29. 79
    zebra says:

    A quick quiz for all those who keep repeating the phrase “a thermometer doesn’t measure temperature”, sometimes followed by “butyaddayaddayadda”.

    OK, what does measure temperature?

    (In case you missed it, this is an illustration of what I was talking about in my comment at #68.)

  30. 80

    The thing about Roberts and people who present “truthy arguments” (nod to Steven Colbert and statistician Howard Wainer) is that they are coated with a skin of plausibility which suffices to get it through the atrophied rhetorical and scientific skills of modern audiences. It helps, of course, if the recipients want to believe an answer, any answer that makes it seem mitigating emissions is not necessary. And the task of the scientifically literate is triply hard. First, they need to establish some kind of trust with the audience, for otherwise the rest of the speech might as well be skilled. Second, they need to deflect the argument presented. Third, to do so, they often need to teach the audience the science they need to understand the deflection and why the original argument cannot be correct. This takes time and effort. It certainly is worthwhile, but there are only so many moles one can whack.

    This is why people like Dr Neil deGrasse Tyson provide such an important and broad service. Bill Nye still does, but he’s somehow been corralled and marginalized in many audiences’ eyes. I do not know why. He’s pretty skilled.

    But the scientifically literate and those that get it can only do so much. After all, what’s being opposed is a deterioration in general education, like rhetoric, and especially maths and science, and its hard to fix all that in one encounter. Jefferson understood, but some of his recent champions forget that.

  31. 81
    Ray Ladbury says:

    Mack evidently lives on a flat Earth that rotates synchronously as it orbits the Sun.

    So, Mack, is your world supported by elephants on the back of a turtle?

  32. 82
    Vendicar Decarian says:

    53 – “doesn’t color correspond to emissivity?”

    Only for a perfect radiator (black body)

    Most solids don’t have an emissivity that differs much from a black body.

  33. 83
    Radge Havers says:

    On Nye, “I do not know why…”

    Maybe there can be a down side to Dancing with the Stars.

  34. 84
    Vendicar Decarian says:

    80 – “An educated citizenry is a vital requisite for our survival as a free people ”

    This is why Libertarian organizations like the Koch (Cato) institute, Competitive Enterprise Institute, the Heritage foundation, the American Enterprise institute have worked for years to abolish public schools and public Libraries.

    Public Libraries you see, are “places of wholesale theft” of intellectual property.

  35. 85
    Jim Eager says:

    Mack, you obviously missed this part of what I wrote, or had no idea what it means:
    “earth’s cross section area integrated over earth’s surface area.”

    Solar insolation is 1350 w/m^2 (actually more like 1368) at top of atmosphere spread evenly over earth’s projected cross sectional area.

    Now spread that 1368 w/m^2 over earth’s surface area by dividing by 4. Since earth’s surface is curved, the top of earth’s atmosphere is also curved, with insolation at maximum at the equator, falling toward zero at the poles where sunlight is tangent to both the surface and atmosphere, the average being 342/m^2.

    So your perceived conflict evaporates.

  36. 86
    Jim Eager says:

    Ray, to be charitable it may just be a case of Mack’s failure to take into account simple geometry. I used to frequently run into a similar failure over Gigatonnes of carbon vs carbon dioxide. Even when I explained the difference (atomic weight of 12 vs 44) I was more often than not met with undeterred incredulity. We’ll see if Mack gets it eventually, or if he really does think generations of scientists could have gotten it that wrong for this long.

  37. 87

    Mack 75: …. ” Joseph Fourier first calculated it in 1824. It’s basic earth science based on the amount of sunlight reaching the top of the earth’s atmosphere (1350 w/sq.m.)…”
    Hang on Jim, if you look at Trenberth’s Earth Energy Budget diagram, he shows 342w/sq.m. solar radiation arriving at the top of the earth’s atmosphere.

    BPL: The Earth receives sunlight on its cross-sectional area, π R^2. But its total surface area is that of a sphere, 4 π R^2. So the amount at top of atmosphere, per unit area, is the Solar constant divided by 4. For the latest TSI figure, 1361.5 W m^-2 (Kopp and Lean 2011), the TOA insolation is then 340.375 W m^-2.

  38. 88

    Silk 78: Let’s be clear here. There is no “radiation from the atmosphere”, in that the atmosphere isn’t /generating/ radiation.

    BPL: Yes it is. The atmosphere is at nonzero temperature and positive emissivity; therefore it radiates, like any other physical body.

  39. 89
    Hank Roberts says:

    You can look this stuff up.
    http://www.infraredtraininginstitute.com/emissivity-of-various-materials/

    > silk
    Nope. Too simple; fails to distinguish which components of the atmosphere absorb and radiate at which wavelengths.

  40. 90
    Scott Strough says:

    @ Silk 78,
    I believe you made the mistake of taking an analogy a bit farther than it applies in the real world. CO2 is largely transparent to visible light from the sun, but largely opaque to infrared light radiating back out to space. So any infrared absorbed by CO2 excites it temporarily and then gets re-emitted back in a random direction. So yes some does head back into space, but some heads back to the surface.

    This means the greenhouse is not really a perfect analogy. Similar in that it helps keep it warm, but not at all due to your explanation of “Let’s be clear here. There is no “radiation from the atmosphere”, in that the atmosphere isn’t /generating/ radiation.” Yes the CO2 is radiating, but randomly in every direction, including back down to the surface.

    Eventually as the air warms, the infrared radiation in every direction increases. So at some point the % radiating up and out to space reaches a new stable equilibrium with the sunlight reaching and absorbed by the earth. That’s when global warming will finally stop. For now though, because CO2 is increasing so fast, warming will increase and continue to increase until it catches up to equilibrium.

    So the net result may be similar to a curtain or a blanket or a greenhouse, but the physics is very different. There is no physical barrier like a blanket preventing the mixing of warm air with cold air, but rather it is caused by CO2 being transparent to certain wavelengths of light but absorbing other wavelengths of light.

  41. 91
    Ray Ladbury says:

    Jim Eager, Yes, any of us can be wrong, but it takes a special brand of hubris and stupidity to think that every single thing we don’t understand is an indication that all the smart people are wrong.

    When Mack says this:
    ” Does Trenberth, (and this “basic earth science” calculation by Fourier…and perpetuated by all the institutes of earth science)have the correct amount of solar radiation arriving at the TOA, (top of the earth’s atmosphere) ??
    Actually, I think not,…”
    It’s pretty obvious that he isn’t interested in checking his math.

  42. 92

    Titus, #77–

    “This opens up a huge issue in as much that the blanket analogy only works on the release of heat from the earths surface (as you appear to agree). However, the earth needs to be heated in the first place which a blanket would restrict.”

    That’s the conceptually neat thing about the greenhouse effect. Because the atmosphere is pretty transparent at visible wavelengths–and BTW, that’s why we evolved visual apparatus that uses that band–the ‘blanket’ admits a good old chunk of energy to the surface. There, it is absorbed (or at least, a good percentage of it is, depending upon albedo. That is analogous to body heat in the blanket analogy.

    “So, the blanket analogy causes thinking folks to question because it doesn’t fit their understanding of a blanket or how the atmosphere works. So I suggest it needs to be removed from the model/concept.”

    IMO, causing ‘thinking folks to question’ isn’t a bug, it’s a feature–eg., this thread. The ultimate learning tool isn’t an analogy, it’s a dialog. Or multilog.

  43. 93
    Chris O'Neill says:

    Fourier…and perpetuated by all the institutes of earth science

    It’s all Fourier’s fault.

  44. 94
    Chris O'Neill says:

    Do you think Fourier and Trenberth are correct at a calculation of 340w/sq.m. shown in the earth energy budget diagrams…or is it 1360w/sq.m. measured 24/7 and accurately by the satellites ?

    Oh no. Someone forgot to multiply by 4!

  45. 95
    Jm Eager says:

    I know, Ray, but as I said, I was being charitable.

  46. 96
    Jim Eager says:

    Oh dear, I just read Mack’s incoherent, sputtering response that deservedly went into The Bore Hole, in which he doubles down. Oh well, you can try to lead the ignorant to knowledge, but you can’t make them think.

  47. 97
    Jim Eager says:

    I know it’s futile for Mack, but one more try for the lurkers, this time step-by-step. Keep in mind that the purpose is to calculate net incoming energy so you can calculate earth’s energy budget.

    Here’s how 1368 w/m^2 insolation at top of atmosphere (TOE) drops to 342 w/m^2 in the diagram above.

    First, earth’s surface is not a 2d flat disc (A = π R^2), it’s a 3d sphere (A = 4 π R^2), which means not every m^2 of illuminated surface gets the same amount of insolation: sunlight/m^2 of surface decreases as you go from the center of the illuminated sphere towards the horizon.

    Second, earth rotates, with every m^2 of surface illuminated for only half of each 24 hour rotation.

    To compensate for both you average that 1368 w/m^2 over the entire surface by dividing 1368 by 4, giving you 342 w/m^2 average. And no, that is not at the surface, that is at top of atmosphere, since all you’ve done is average 1368 over the total area of the surface.

    Now, on its way down through the atmosphere some of that 342 w/m^2 of sunlight will be reflected back out to space, scattered or absorbed by clouds and aerosols ( 77+67 w/m^2 in the diagram). And when the rest reaches the surface some more will be reflected right back upward by snow, ice, water, light coloured sand, etc (30 w/m^2). That reflectivity is called earth’s albedo.

    That is how 342 w/m^2 TOE drops to an average of 168 w/m at the surface, just as Trenberth’s diagram shows.

    Now, some places will obviously get more than 168 w/m^2. A lot more, such as at local noon on the equator, but some places will get a lot less, such as that same place on the equator just before sunset. And of course that same place will get zero insolation at night. That’s why we averaged over the entire surface area.

  48. 98
    Digby Scorgie says:

    I notice a lot of talk about bodies being warmed under blankets. In the case of the Earth’s “blamket”, however, would it not be fair to say that one would not want to lie naked under it? The reason being that the “blanket” is transparent in the visible spectrum but not in the infrared.

  49. 99
    Titus says:

    Kevin McKinney @92 A ‘Feature’. I like it!! Getting into the old Greek philosophers way of deliberating.

    I’d appreciate a view on the way I have understood the climate from my younger days playing with basic electronic circuits. Put very simply:

    What do you think of the analogy of the earth acting like a ‘capacitor’and the atmosphere as a resistor?
    The earth absorbs radiation and heats up then releases it slowly (land and water will have differing effects). The atmosphere then acts as a resistor to the radiation released back from the surface into space and secondly sets up a continuous loop back circuit to the capacitor (earth).

  50. 100
    Mack says:

    Oh well, I might as well try to make a comment on topic and hope it doesn’t wind up in The Bore Hole, Jim.
    Let’s see, Stephan, and the rest of you, are rabbiting on about the atmosphere acting as a blanket. Stephan has obviously forgotten the basic properties of all gases…ie gases do not add energy ,but disperse it. Gases in the atmosphere all dissipate heat. Stephan could find this out for himself by holding a REAL blanket closely over his head, and running his hairdryer.