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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

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Comments 106101 to 106150:

  1. Blaming global warming on the oceans - a basic rebuttal
    TimTheToolMan, water evaporates all the time, and it precipitates all the time. There are spatial and temporal lumps in the atmosphere's water vapor content, but as barry wrote, the overall average is determined by temperature and pressure of the atmosphere, not by temperature of the water pools.
  2. Blaming global warming on the oceans - a basic rebuttal
    "Evaporation occurs all the time at the surface of the oceans" Are you suggesting a warmer ocean wont affect the moisture levels in the atmosphere? What about convection?
  3. CO2 lags temperature
    mistermack, lots of factors influence temperature. Although CO2 is a really important one, it is not the only one. The interplay of those factors is complicated. Our knowledge of that interplay is summarized in causal models. Those models do a good job of hindcasting the changes in temperature in response to changes in those factors.
  4. CO2 lags temperature
    mistermack, your incorrect analogy with a moving ball makes me suspect that you are incorrectly thinking of temperature as having inertia.
  5. The 2nd law of thermodynamics and the greenhouse effect
    stylo, #38. The incoming solar and outgoing terrestrial radiation spectra are different (different temperatures of sun and earth). GHGs selectively block frequencies nearer the peak of the earth's spectrum, so they stop only a small fraction of the incoming energy but a larger fraction of the outgoing energy. So a portion of the spectrum becomes essentially unavailable for the earth to use to radiate away energy, and it warms up until it emits enough energy at other frequencies to maintain the balance. If it helps, you can think of it as effectively lowering the emissivity of the earth at certain frequencies, by lowering the transparency of the atmosphere to those frequencies.
  6. CO2 lags temperature
    In any case, Archie, for that to happen, the CO2 graph would have to get ahead of the temperature graph.
  7. CO2 lags temperature
    Archie, that's totally illogical. If you consider the peaks of the graphs, you have a huge steep rise, coming to a sudden stop, followed by a huge steep fall. How on earth does that happen in response to CO2 feedback? Does the ocean suddenly stop outgassing, and suddenly start sucking in CO2? In huge quantities? How would that happen?
    Moderator Response: Again, you seem to be assuming that putting the label "positive feedback" on any phenomenon necessitates the runaway version of positive feedback. See the Argument "Positive Feedback Means Runaway Warming", and read all three versions--Basic, Intermediate, and Advanced.
  8. Blaming global warming on the oceans - a basic rebuttal
    Evaporation occurs all the time at the surface of the oceans, but it is the temperature (and pressure) of the atmosphere that determines how much water vapour accumulates (on average), as per the Clausius–Clapeyron relation.
  9. CO2 lags temperature
    @mistermack: you don't seem to understand that climate feedbacks don't necessarily lead to runaway warming. Did you read the article I linked to earlier? "In climate terms, that would require the CO2 to run out, or the process of outgassing from the ocean to suddenly stop." There is a finite amount of CO2 sequestered in the oceans, so it is possible that the rate of CO2 release from oceans would slow down as that amount decreases. Your analogy is inadequate, and your conclusions are thus erroneous. I suggest reading more from this site before attempting to take down current AGW theory.
  10. The 2nd law of thermodynamics and the greenhouse effect
    #39, cont'd: Stylo: So the point is that a little bit from solar input is worth just a little bit from the heat-radiation output: When compared on an apples-to-apples basis, total solar input to the Earth is essentially equal to total Terran heat-radiation output. So the point still stands: Additional water vapor will do much more to reduce the heat loss than it does for blocking incoming solar radiation.
  11. CO2 lags temperature
    There seems to be very poor understanding of feedback among posters, so I'll try to give a simplified description. Imagine you have a football, (soccer), and a golfball. Chop the football in half, and lay it on the ground as a bowl. Put the golfball inside. That's negative feedback. If anything disturbs the golfball, it will roll back to the middle. Turn the football over, and put the golf ball on top. A very slight forcing factor ( a breath of wind ) causes it to roll. Once it's on the down slope, gravity, the feedback mechanism, takes over, and the ball runs away. It no longer needs the wind that started it, and wind in the other direction can't blow it back up the football. So those who claim that a reverse in the level of insolation would stop a feedback mechanism are really not understanding what's happening at all. For that to happen, the feedback would have to be incredibly weak, nowhere near what could pull a planet out of an ice-age. In reality, it's removing the feedback power source that stops positive feedback loops, like turning down the volume knob on your guitar amplifier. In climate terms, that would require the CO2 to run out, or the process of outgassing from the ocean to suddenly stop.
  12. The 2nd law of thermodynamics and the greenhouse effect
    #38, Stylo: According to the wiki on the Earth's energy budget (http://en.wikipedia.org/wiki/Earth%27s_energy_budget ), 1366 (W/m^2) is the instantaneous intensity of the sunlight at 1 AU. However, to compare that with the radiated power from the Earth, you have to convert that into a surface-area average. That gives a factor of 4. More explicitly: - The solar constant S = 1366 (W/m^2). The cross-sectional area of the Earth is pi*R^2, so the total power absorbed from the sun is P_in = S * (pi*R^2) = pi * R^2 * S (The point is that, at any one time, the sunlight only shines on the daytime half of the Earth; and you have to take the tilting of the surface relative to the rays. Both issues are taken care of by using the cross-sectional area to calculate total absorbed power.) - The time-averaged power radiated away through heat radiation, per unit area, is B (W/m^2). Therefore, the total heat radiation lost to space is: P_out = B * 4*pi*R^2 = 4 * pi * R^2 * B (This is emitted day and night, so over the entire area of the Earth.) - Since P_out is, on the average, almost perfectly equal to P_in, 4 * pi * R^2 * B = P_out = P_in = pi * R^2 * S so: B = S/4 = 1366/4 = 341.5 (which is close enough to 342 for government work). So the match is perfect, to within the precision of these numbers. (If there were a 1366 - 342 - 1024 (W/m^2) difference between input power and output power, we would not be talking about "global warming": We would comparing recipes for "global roasting"!)
  13. Blaming global warming on the oceans - a basic rebuttal
    @kdkd : "Only one of these three things (c02, h20(g) and h20(l)) is the primary causal agent." What about something else entirely heating the oceans?
  14. Blaming global warming on the oceans - a basic rebuttal
    @barry : "Gray's argument infers ocean cooling." This is a fair comment. He seems to say the following in the article... "This small warming is likely a result of the natural alterations in global ocean currents which are driven by ocean salinity variations." ...so yes its implied in his statement. However it takes a warmer ocean to increase the amount of water vapour (when it cools) so he's also implying warming in his natural alteration statement. " he is certainly not saying that water vapour is a driver." Nobody is saying that.
  15. Blaming global warming on the oceans - a basic rebuttal
    Indeed, he states that water vapour is a negative feedback - he is certainly not saying that water vapour is a driver. Never mind that his various statements are completely at odds with the consensus of evidence.
  16. Blaming global warming on the oceans - a basic rebuttal
    Gray attributes the warming to ocean heating
    No, Gray's argument infers ocean cooling. He posits that oceans are losing heat to the atmosphere, driven by salinity variation in the oceans - not water vapour.
  17. Blaming global warming on the oceans - a basic rebuttal
    TTM: Circular logic: "The theory goes CO2 drives the warming of the oceans and through increased water vapour, the oceans drive the warming of the earth." Only one of these three things (c02, h20(g) and h20(l)) is the primary causal agent. Your statement can only be true if we assume that none of the above are the primary causal agent. The scientific theory tells us that co2 is the primary causal agent, therefore can be described as the "driver" of the system under examination. The "none of the above" answer could be true on some level of analysis, but is not a terribly useful proposition for the present discussion.
  18. The 2nd law of thermodynamics and the greenhouse effect
    #36 nealjking, re: the graphs: the incoming from the sun is 1366 W/m2 but the outgoing is only, what, 342 W/m2? So a little out of the sun's is worth a lot out of the earth's energy flow in terms of greenhouse blocking. #37 TonyW, 1. "your first blanket would radiate away heat because it is cooler." It would be cooler but, without convection-cooling from the air the blanket would just get to the same temperature as the body and radiate away just as much. So, radiation blocking is not really a mechanism of heat trapping. 3. By passively warmed I just mean it doesn't have its own power source and so can't add to the temperature like, say, a lowered emissivity could.
  19. Blaming global warming on the oceans - a basic rebuttal
    "There are no indicators of ocean heat driving temperature changes that are supported by the evidence." There is nothing tricky about this. Gray attributes the warming to ocean heating and doesn't attribute the ocean warming to CO2 (presumably he thinks its something else) and AGW theory attibutes the warming to ocean heating and does attribute the ocean warming to CO2 So I think the statement at the top that I requoted is inadequate in the context of this rebuttal. I'm not quite sure how you get that I'm using circular logic. Perhaps you could explain that?
  20. Waste heat vs greenhouse warming
    #317: "the amount of waste heat per year is around 474 x 10E18 J according to the link you provide above," You seem to equate all energy use with 'waste heat', using the 474e18 J given in said link as if none of that heat went to heat water or heat solids. I wonder why no one else does it this way. For example, a very thorough study of the US industrial processes concluded that of the 32e15 BTU (34e18 J) consumed in 2008 by US industry, "as much as 20 to 50% of the energy consumed is ultimately lost via waste heat contained in streams of hot exhaust gases and liquids, as well as through heat conduction, convection, and radiation from hot equipment surfaces and from heated product streams While industry uses only about one third of the total US energy consumption and the US is only a fraction of the entire world's energy consumption, there's a long way between 34x10^18 J and the 474x10^18 J you've used.
  21. Blaming global warming on the oceans - a basic rebuttal
    TTTM: #8 No, on the face of it your argument looks like circular reasoning. If you think that you have a valid argument, you must spell it out for us clearly and unambiguously. Insinuating that there's some special insight that you have that we can become privy to if we just think about it in the right way is not a terribly valid argument. I think you need to spell it out for us, so that we can assess its arguments on your merits, not on what we think that you think that it means. #9 Yes, there's some sort of optimisation function that will show you the conditions necessary to meet these conditions. Perhaps that work has already been done in the literature, or perhaps the algebra is straightforward. Perhaps you could enlighten us as to the conditions that are necessary to confirm your hypothesis?
  22. Blaming global warming on the oceans - a basic rebuttal
    "My analogy: I cannot get richer by giving away my money unless I have a donor that is giving me money at a faster rate than I am giving it away." This is an interesting point. Were you aware of the rate at which energy is both input into the ocean from the sun and radiated away from the earth? Roughly the amount of ocean heat that was accumulating each year when it was accumulating energy quickly some years ago is the same as the oceans recieves in just one day from the sun. There is plenty of energy around to both heat the oceans and have it produce increased water vapour.
  23. Blaming global warming on the oceans - a basic rebuttal
    @cbp, Yes but this is rebuttal against someone who also is saying oceans drive the warming. Do you see the problem with the statement now?
  24. Blaming global warming on the oceans - a basic rebuttal
    I recall having this conversation with a skeptic on my blog several months ago. I asked him how it was possible that the oceans were releasing heat to cause the climatic warming and yet were still gaining heat themselves? My analogy: I cannot get richer by giving away my money unless I have a donor that is giving me money at a faster rate than I am giving it away. I try to use money examples because people seem to relate well to money (it makes cents). {groans expected}
  25. Blaming global warming on the oceans - a basic rebuttal
    @TimTheToolMan I would assume the author's use of the term 'driving' refers to the culprit initiating the warming, not any of the ensuing feedback cycles. The 'driver' of car is the person behind the steering wheel, not the axle.
  26. Waste heat vs greenhouse warming
    RSVP #317 Woops. Sorry, there is a typo, 474 x 10E21 J, where the exponent should be 18. This doesnt affect the calculation.
  27. Waste heat vs greenhouse warming
    KR #301 "...you could have done this yourself" Would you have used my formula? I doubt it. At any rate, it appears you do agree there is something going on here as you say "waste heat... might at equilibrium add 0.015°C to 0.034°C. ". Before assuming losses, why not first determine how this waste heat might raise temperature? If the volume of air is assumed, 4.2 billion cubic kilometers, according to http://wiki.answers.com/Q/What_is_the_volume_of_Earth's_atmosphere air´s heat capacity cp = 1.0 kJ/kg C, according to... http://www.engineeringtoolbox.com/air-specific-heat-capacity-d_705.html the mass of air, roughly 1.2 kg/m3 @ 15 C, according to http://ballonsolaire.pagesperso-orange.fr/en-theorie1.htm and the amount of waste heat per year is around 474 x 10E18 J according to the link you provide above,...calculating.. 4.2x10E9 km3 = 4.2x10E18 m3, whih yeilds 5x10E18 kg, multiply by cp (10E3 J/kgC), you get 5x10E21 J/C, which means it takes that much energy to raise the atmosphere temp 1 degree C. That seems like a lot of energy to me. But according to the link you provided, the amount of waste heat per year is 474 x 10E21 J. Taking this value .474x10E21 J and dividing by the amount of energy required as calculated above (5x10E21 J/C) We get 0.0948 C. Rounding up, that's 0.1 C per year. If one assumes all of this energy is lost to space, then all of global warming is likely due to GHGs. But since AGW assumes the ability of the atmosphere to radiate energy is getting worse as time goes on, it has to be assumed that some portion of this energy is not escaping, and is therefore accumulating. Assuming (just for grins) only a tenth of this energy is retained. This would yeild a .01 C increase each year. After on century you get an increase of 1 C. But 1 or 2 degrees C is roughly what GHG are supposedly adding to global temperatures over the next century in the best of circumstances, and perhaps more in the worst of circumstances, which could have also been achieved by assuming just a little more waste heat being retained. Concluding... it looks like ignoring waste heat is literally "playing with fire". But that is just a skeptic talking.
  28. Blaming global warming on the oceans - a basic rebuttal
    TTTM No you certainly didn't explain that well. You appear to be providing a circular argument - a form of logical fallacy. Remember that unlike anthropogenic climate change, logic is something that we can prove is true or false. Think about it like this: If we have a x quantity of CO2, then the amount of water vapour in the atmosphere will go up by y such that y = f(x). To the extent that the oceans exist, and they contain the largest surface area of water with which to create vapour, we can solidly assume that the oceans drive water vapour greenhouse feedback. This is not the same proposition as 'the oceans drive warming'.
  29. The 2nd law of thermodynamics and the greenhouse effect
    Tarcisio, #30. I'm sorry, I do not understand what you are trying to say. Stylo, #31. 1. your first blanket would radiate away heat, but slower than your body alone would do so because it is cooler. That's why you warm up. A second blanket would slow down the heat-loss from the first blanket for the same reason, so you would still get warmer. sure, there is a physical limit in this analogy, eventually you would die of heat-stroke and stop emitting heat. Then you and your blankets would all cool down. 3. What do you mean by 'passively warmed'? The earth is being actively warmed by the sun. Energy is being pumped into it by solar radiation. Nothing requires heat to flow from the atmosphere to the earth, we need only slow the rate of loss of heat by the earth, and it will get warmer. That's what GHGs do.
  30. Blaming global warming on the oceans - a basic rebuttal
    I dont think I explained that well. Read his statement again. Critically read it.
  31. Blaming global warming on the oceans - a basic rebuttal
    kdkd, The theory goes CO2 drives the warming of the oceans and through increased water vapour, the oceans drive the warming of the earth. Its a matter of perspective.
  32. Blaming global warming on the oceans - a basic rebuttal
    TTTM No, the water vapour content of the atmosphere is proportional to the temperature. It follows, not leads temperature. As it follows temperature it can not be driving warming.
  33. The 2nd law of thermodynamics and the greenhouse effect
    #31, Stylo: 1. On blankets: This relates to an analogy rather than physics, so I'll leave it aside. 2. "Doesn't water vapor block radiation coming from the sun? Shouldn't increased water vapor act as a negative feedback?" Yes, water vapor does block some infrared (IR) radiation at high frequencies. However, if you look at these absorption bands in the context of the two blackbody-radiation graphs, you find: - Your first graph shows the spectrum of incoming radiation from the sun. - Your second graph shows the spectra from both the incoming radiation and the outgoing radiation (from the earth, headed into space). - The water-vapor lines have taken a bit out of the solar-radiation emission spectrum (which is mostly in the visible and higher-frequency IR), but nearly wipe out about 2/3 of the earth-radiation spectrum: This can be seen in your 2nd graph. - So if you add more water vapor, you cut back on radiant input (solar) a bit, but you cut back on radiant output (into space) a lot. - Since the water vapor has a huge percentage impact on the earth-radiation spectrum but just a minor effect on the solar-radiation spectrum (and since the total power under both these graphs have to be very very nearly the same (SEE NOTE)), the overall impact of additional water vapor will be to increase the warming effect. 3. "Heat does not flow from cooler to warmer." - True, if you put a cold object in direct physical contact with a warm object, heat will be conducted only from the warmer to the cooler, not the other way. - But we are not talking about heat conduction, we are talking about radiant energy transfer. There is no 2nd-law problem with SOME radiated power from the cooler object (which still gives off radiation, remember: Power proportional to (temperature)^4 ) being absorbed by the warmer object. This doesn't violate the 2nd law because EVEN MORE power radiated from the warmer object is absorbed by the colder object. So the net transfer of heat is going to be from warmer to hotter. There is no problem with this. - Perhaps you are getting confused by the old-fashioned language of heat engines, etc. A slightly more abstract but simpler, and equivalent, approach is to think of it in terms of entropy: The 2nd law states that the entropy of the universe can only increase; so a process that would result in a decrease of entropy would violate the 2nd law. Example: Heat (dQ) flows from hot object 1 to cold object 2 (T_1 > T_2): the entropy change is: dS = (1/T_1)*(-dQ) + (1/T_2)*(dQ) = (1/T_2 - 1/T_1)*dQ = {(T_1-T_2)/(T_1*T_2)}*dQ Since T_1 > T_2, dS > 0, and this is OK by the 2nd law. But if you try having dQ be negative (heat flowing from cold object at T_2 to hot object at T_1), you will get dS < 0. WARNING! That means it's impossible. So heat conduction will ALWAYS and ONLY be from the warmer to the colder body. But now let's consider radiant transfer: Both bodies at T_1 and T_2 are radiating energy away, and absorbing whatever radiant energy falls upon them. The energy that is radiated from object 1 and absorbed by object 2 is proportional to the intensity of the radiation from object 1, I_1. Correspondingly, the energy radiated from object 2 and absorbed by object 1, in time dt, is proportional to the intensity of radiation from object 2, I_2. Since T_1 > T_2, I_1 > I_2 (Stefan-Boltzmann law). (The constants of proportionality are the same, because they are determined by geometrical considerations which are reciprocal between the two objects.) Hence, the entropy increment associated with the radiant energy flow from 1 to 2 is: dS_a = -(1/T_1)*(I_1 * dt) + (1/T_2)*(I_1 * dt) .....= {(T_1 - T_2)/(T_1*T_2)}*(I_1 * dt) Likewise, the entropy increment associated with the radiant energy flow from 2 to 1 is: dS_b = (1/T_1)*(I_2 * dt) - (1/T_2)*(I_2 * dt) .....= {(T_2 - T_1)/(T_1*T_2)}*(I_2 * dt) Now, if we look at dS_a, we see that dS_a > 0 because T_1 > T_2: no problem. But if we look at dS_b, we see that dS_b < 0. Does that mean that process b (radiant flow from object 2 to object 1) is impossible? NO, not if it is done as part & parcel with process a (and it WILL be part & parcel: as soon as radiation can go from 1 to 2, it can also go from 2 to 1): In that case, dS_total = dS_a + dS_b .........= {(T_1 - T_2)/(T_1*T_2)} * (I_1 - I_2)*dt and this is > 0, because T_1 > T_2 and I_1 > I_2. Hence, when you put processes a and b together, it's completely legitimate with regard to the 2nd-law. You might ask, "Is it legal to do that? To combine a process that would seem to be illegal alone with another so that the total is legal?" Yes, it is: Consider the Carnot cycle, run in refrigerator mode: It takes heat from a cooler object and deposits in a hotter object (horrors!). It's all legal, because the work you have to put in to make it balance ensures that the total entropy change is non-negative. That means it's fine from a 2nd-law perspective. And that's a good thing for those bottles of beer you have in your 'fridge. NOTE: Someone might wonder, "Why is the total power under the solar-radiation input curve the same as the total power under the earth-radiation output curve? Isn't the sun much hotter, and so doesn't the Stefan-Boltzman law state that the sun must be radiating much more energy?" The answer is Yes, the sun is radiating much more energy in total; but we're just receiving a fraction of it, as we are at a distance 1 AU away from the sun, and so the intensity of the radiation we receive is reduced by factor (1/distance^2). Whereas we are sitting on the earth, and get the full benefit of the blackbody emission spectrum from it. Since the earth is only warming slowly, the total influx must very nearly balance the total outflux; therefore the integrated powers have to be very nearly the same.
  34. Blaming global warming on the oceans - a basic rebuttal
    "There are no indicators of ocean heat driving temperature changes that are supported by the evidence." Did you really just say that? Water vapour feedback is considered by AGW theory to dominate the heating and that comes from the warmer oceans. Perhaps you need to rephrase what you mean to be a bit more specific?
  35. Climate cherry pickers: Falling humidity
    "And John, do you have ANY evidence at all that water wapor never acts as a forcing?" How do you get water vapour to change without something else (eg temperature rise) first causing it? The cause of the temperature rise is the forcing not the water vapour.
  36. The 2nd law of thermodynamics and the greenhouse effect
    Glenn Tamblyn, I understand your point (and ProfMandia). It's difficult to judge what should and what should not be said in a basic level explanation. If a user has no previous kowledge, the simple blanket analogy is easy enough. A blanket reduces your body heat losses, the GHGs do the same with the earth. No details, no conduction, radiation or Plank, but essentially it shows that putting something less cold than the ambient near a warm body helps keep it warm by reducing heat losses. The 2nd law is not addressed explicitly; the analogy just shows that what may seem to violate the 2nd law, in reality does not. In my view, it is an intermediate level explanation that should explicitly mention the mechanism to explain why the second law is not violated. In the end, it all depends on the audience one immagine to have when writing a post. I myself wrote a few posts here and the hardest part was answering to the question "to whom am I talking?". The problem is that there's no single answer or, better, the real answer is "to everyone".
  37. Philippe Chantreau at 19:08 PM on 24 October 2010
    The 2nd law of thermodynamics and the greenhouse effect
    Stylo exhibits the common confusion that has so succesfully been exploited in this non debate. Even G&T do the same thing: confuse heat (in the thermodynamic sense) and energy, or radiation.
  38. The 2nd law of thermodynamics and the greenhouse effect
    Riccardo @20 "it shouldn't be necessary to add "net" to heat, it is already the net energy exchange (or flux)" Of course it is, but that is when speaking to a moderatly technically literate audience. I have had sceptics tell me that down-welling longwave radiation can't exist because heat cannot radiate from a cold atmosphere to the warmer Earth's surface. This is the point, particulary with the basic posts. They have to provide information to the undecided who for example have never heard of this "Stefan Boltzman guy" (I have encountered this) in simple form without providing fodder for deliberate or ignorant mis-representation along the lines of: "I was over at this warmist site and they didn't even understand that heat can't flow from a cold source to a hot source. These people are trying to con us all with this junk science ... blah ... blah ..."
  39. Waste heat vs greenhouse warming
    @RSVP: "...electricity that in turn produces heat, which generates IR, which generates electricity.... you could call it the Perpetual Motion Heat Diode Energy Saver, patent pending." You seem to miss the point that it's "waste" heat. The amount wasted being less than the amount recycled...well, you can figure out the rest. Hopefully. "Sorry, I missed an important nuance of your idea for recycling energy, and that is you only wanted to recycle waste heat." Nowhere did I read that CBD wanted to only recycle waste heat. You're really grasping at straws, now. It seems as though you're not even trying anymore.
  40. Waste heat vs greenhouse warming
    #311 Sorry, I missed an important nuance of your idea for recycling energy, and that is you only wanted to recycle waste heat. What about all that excess heat from GHGs? Whos side are you on anyway?
  41. Waste heat vs greenhouse warming
    CBDunkerson #311 "By then we might have perfected infrared rectifying antennas and be turning 'waste heat' itself into electricity." ...electricity that in turn produces heat, which generates IR, which generates electricity.... you could call it the Perpetual Motion Heat Diode Energy Saver, patent pending.
  42. The 2nd law of thermodynamics and the greenhouse effect
    #25 ProfMandia at 08:26 AM on 24 October, 2010 "Increased GHGs keep the surface warmer due to changes in radiative transfer and a blanket keeps the body warmer by suppressing convection." Indeed the primary reason a green house is warmer is because of the suppressed convection. So the mechanism of "greenhouse" gases starts off with a basic confusion. The easiest way I've found to explain the GHG effect is to ask someone to compare a dry cloudless night with a humid cloud-covered night. Using this as the example, it isn't very hard to get across the concept of the surface radiating upward and that energy getting reflected either just a little (clear, dry night) or a lot (humid, cloudy night).
  43. The 2nd law of thermodynamics and the greenhouse effect
    1. A blanket is opaque to IR just as much as to light. If a blanket warmed by absorption and emission, rather than by blocking convection, then the first blanket -- blocking 100% of the IR radiation -- would do all the warming that could occur and a second blanket could cause no further warming (contrary to reality). 2. If greenhouse is a blanket that sends some heat back the way it came then this must be true of the radiation coming in from the sun as well as going out. Notice these two diagrams show that water vapour absorbs far more frequencies of radiation, especially incoming from the sun, than CO2. Therefore water vapour would provide a negative feedback, cooling the earth. 3. Even though there's radiation from the cooler atmosphere to the warmer ground, heat does not flow from the cooler to the warmer. An object passively warmed can't make the warming object warmer than it otherwise would be unless you believe you can get energy for free. Yet, remarkably, this fallacy is the basis of the greenhouse effect.
    Moderator Response: You should read the Intermediate version of 2nd law of thermodynamics contradicts greenhouse theory. Then read CO2 effect is weak, both the Intermediate and Advanced versions.
  44. Tarcisio José D at 14:10 PM on 24 October 2010
    The 2nd law of thermodynamics and the greenhouse effect
    TonyWildish Suponha uma antena trnsmitindo 1W e outra recebendo este sinal num ponto tal que seja induzidos 1 dBm (1mW). Divida então este 1W de sinal e aplique em 1000 antenas. Em nossa antena receptora teremos 1w de sinal. Como ? dirias e a segunda lei da termodinamica ?. No caso da atmosfera ocorre a mesma coisa. São 6.022 E23 antenas por moll de ar transmitindo IR (ondas eletromagneticas). Translated by google Kooiti Matsuda Voce está correto, mas apresentei apenas um exemplo local sem o intuito de apresentar avoles absolutos. Mostrando que o fluxo energetico que chega ao solo é maior que a energia enviada pelo sol. TonyWildish Suppose an antenna trnsmitindo 1W and the other receiving this signal at a point that is induced 1 dBm (1mW). Then divide this signal and apply 1W in 1000 antennas. In our receiving antenna will 1w signal. How? would you say and the second law of thermodynamics?. In the case of the atmosphere is the same thing. 6022 E23 St antennas for transmitting IR moll air (waves electromagnetic). Kooiti Matsuda You're right, but has just one local example without the intention of presenting absolute avola. Showing the energetic flow that reaches the ground is greater than the energy sent by the sun.
  45. The 2nd law of thermodynamics and the greenhouse effect
    Re: Kooiti Masuda (27) I pulled these references off of Barton Paul Levenson's Climatology pages (he specializes in atmospheric physics):
    Goode, Philip 1998. "Earthshine Measurements of Global Atmospheric Properties." http://www.bbso.njit.edu/Research/Earthshine/earthshine-proposal.html, accessed 10/13/1998. Houghton, J.T. 2002 (1977). The Physics of Atmospheres. Cambridge: Cambridge University Press. Lorenz, R.D. and C.P. McKay 2003. "A Simple Expression for Vertical Convective Fluxes in Planetary Atmospheres." Icarus 165, 407-413. Trenberth, K.E., J.T. Fasullo and J. Kiehl 2009. "Earth's Global Energy Budget." Bull. Amer. Meteorol. Soc., preprint.
    BPL also has an online planetary temperature calulator here. Not exactly what you may have been looking for, but I hope it helps! The Yooper
  46. The 2nd law of thermodynamics and the greenhouse effect
    I think that the blanket analogy is less troublesome than greenhouse (glass house) analogy, for a blanket is obviously different from the atmosphere. By the way, I remember some planetary scientists use "blanket effect" as a technical term distinguished from "greenhouse effect". But, I do not remember the precise context. Probably, it is "greenhouse effect" if energy comes primarily from the sun, and it is "blanket effect" if it comes from the interior of the planet (geothermal).
  47. The 2nd law of thermodynamics and the greenhouse effect
    Help please! I do not find good textbooks of thermodynamics which contain how to interpret radiative transfer as heat exchange. Some books do contain Planck's theory of blackbody radiation, but that is not enough. Even if we are content with the blackbody spectrum, we need to handle different energy flux densities from the thermal equilibrium. We also need to evaluate the effective tempearture of radiation after partial absorption.
  48. The 2nd law of thermodynamics and the greenhouse effect
    Tarcisio José D'Avila, the value 1368 W/m2 is the energy flux coming from the sun to the unit area of a plane surface perpendicular to the line between the sun and the center of the earth. To get the value of solar energy flux per unit area of the earth's surface, it should be multiplied by the cosine of the solar zenith angle (in other words, the sine of the solar elevation angle), which depends on latitude, season, and time of day. (We are sure that the global and annual average of it is 1/4). There are many textbooks, both meteorological and astronomical, to explain how to calculate it. As for a conceptual reminder, here is an introduction from NASA. http://edmall.gsfc.nasa.gov/inv99Project.Site/Pages/science-briefs/ed-stickler/ed-irradiance.html
  49. Do critics of the hockey stick realise what they're arguing for?
    @protestant: "Anyway what we know is the temperatures always fell when CO2 was high and still rising for centuries...." It didn't "always fall" - you identified a single instance of this. In any case, that question was already answered: in normal Milankovitch cycles, CO2 is a feedback mechanism - the main forcing is orbital variations, which then cause increased albedo and lower CO2 as temperatures go down. In the current situation, anthropogenic CO2 is acting as a forcing. "CO2 follows the temperature, not the otherway around." Actually, it's both. Look, it's clear your mind was already made up that AGW wasn't real when you came here. You tried to challenge the science, and when presented with evidence of how you're wrong, you start complaining about it. To people like me, who come here to learn, you're just another random Internet contrarian, repeating the same old debunked arguments.
  50. Vote for SkS in the physics.org web awards
    @protestant: Actually, it is the contrarian's arguments that require a lot of cherry-picking and ignore the overwhelming evidence supporting AGW theory. This site is about finding the truth. I encourage you to continue learning about the science and abandon your naive belief in the pseudo-science bandied about by contrarians. If you aren't interested in learning more about science, then I suggest you just go someplace else where your preconceived notions will be welcome, such as WUWT.

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