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Post by jimg on Mar 31, 2009 5:48:25 GMT
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Post by kiwistonewall on Mar 31, 2009 10:37:18 GMT
Socold, the statement you made "Because it shows the net flow in and out of the atmosphere rather than internal transfers in both directions." is thermodynamically meaningless.
There is no "internal transfer of radiation" in the mathematics of heat transfer. In other words, it is excluded. The reason is quite simple. Heat transfer between any object (your layers, the earth surface etc) depends on temperature difference.
There is NO NET BACK radiation from the colder (on average) atmosphere to the warmer earth. (That idealised diagram is an annual and global budget)
The fact that two bodies at temperature equilibrium are happily radiating energy toward each other (which has no net effect) is ignored by the mathematics.
So on AVERAGE, the atmosphere is cooler than the Earth surface, and Heat is therefore, only considered moving from Earth outwards. (Which is the average sate of affairs.)
We don't consider that the Earth warms the Sun. Why not? Some of the Earth's radiation surely reaches the solar surface? Thermodynamically, it is ignored. In Net terms, heat energy can only move from warm to a cooler body.
If 1000 units of Heat move from A to B, we don't create a new "thermodynamics" and say
1000.00001 units of Heat move from A to B and .00001 units move from B to A. (numbers are purely for illustration)
All thermodynamics has been built strongly on real experimental results. That is why all our equations deal with the net observable effects, the heat moving from warm to cool. It is the only real situation. As Heat NEVER moves from cool to warm bodies in any real observable way, that is how we talk about it.
Saying, "but radiation does move from the colder object to the warmer object" is actually true, but swamped by the radiation in the other direction. The mathematics of thermodynamics ONLY (has always) measured the net effect.
Therefore, the "greenhouse diagrams" are works of fiction, and the NASA diagrams are thermodynamically correct.
Of course, at any point of time (not the annual global average) latent heat may warm the atmosphere, and the Earth's surface may cool overnight. THEN, we have a real situation where energy will be radiated toward the Earth. But the average state is radiation outward.
In in none of this are "greenhouse gases" at play in any particular sense- the entire atmosphere is radiating.
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Post by trbixler on Mar 31, 2009 12:45:45 GMT
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Post by gridley on Mar 31, 2009 14:28:22 GMT
I know it is backtracking a bit, but I would still greatly appreciate replies to this: The water vapor is known to vary around the globe and from various satellite images so does CO2 but because it is such a trace gas that it has not been measured on a regular basis in a global fashion. It is assumed that the ppm match that of Mauna Loa or the few measuring sites. The gradation of CO2 in the atmosphere is assumed as well, not measured. Factors of 3 to 100 based on assumptions. Then on top of the assumptions what is the % of Human produced CO2. Hello all, I've been lurking for several months since I didn't feel I had anything to add, but I have to ask some of the 'warmers' to PLEASE respond to this, and I would also appreciate it if trbixler would expand their comments somewhat. 1. What assumptions about the variable distribution of CO2 in the atmosphere are included in the global climate models? 2. How many stations (aside from Mauna Loa) exist that have multi-year measurements of CO2 concentration, and by how much do these values differ at any given point in time? The reason I'm so interested in this is that I tend to view all thermodynamic problems (at the 1st order level) via the electrical analogue model, and in such a model an uneven distribution of insulation (resistance) has of course a very different result from an even distribution of the same total amount. I've always assumed that the distribution of CO2 and other greenhouse gasses was not a matter of dispute. If the electrical analogue model is invalid in this case, I would also appreciate an explanation as to why that is the case. Thank you, Gridley
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Post by poitsplace on Mar 31, 2009 14:49:16 GMT
I know it is backtracking a bit, but I would still greatly appreciate replies to this: Hello all, I've been lurking for several months since I didn't feel I had anything to add, but I have to ask some of the 'warmers' to PLEASE respond to this, and I would also appreciate it if trbixler would expand their comments somewhat. 1. What assumptions about the variable distribution of CO2 in the atmosphere are included in the global climate models? 2. How many stations (aside from Mauna Loa) exist that have multi-year measurements of CO2 concentration, and by how much do these values differ at any given point in time? The reason I'm so interested in this is that I tend to view all thermodynamic problems (at the 1st order level) via the electrical analogue model, and in such a model an uneven distribution of insulation (resistance) has of course a very different result from an even distribution of the same total amount. I've always assumed that the distribution of CO2 and other greenhouse gasses was not a matter of dispute. If the electrical analogue model is invalid in this case, I would also appreciate an explanation as to why that is the case. Thank you, Gridley I'm uncertain as to the actual number of groups monitoring CO2. Also the CO2 data is HIGHLY smoothed since it varies quite a lot. I've seen maps of CO2 concentration...I guess they get it from the AIRS satellite photojournal.jpl.nasa.gov/catalog/PIA10645CO2's density (which is all that matters, PPM at sea level is just a general guide they use) also varies with altitude...and much of the spectrum of CO2 happens to be absorbed by water vapor...which then emits over a significantly larger spectrum (at least twice as large). While CO2 varies almost uniformly with altitude, water vapor stops rather abruptly...right at the altitude where it dumps off all its latent heat. that info help any?
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Post by trbixler on Mar 31, 2009 15:25:16 GMT
Gridley Notice the date on the jpg that was supplied it is 2003. For some reason there is very little discussion of the magic gas CO2 other than it is always well mixed, which disagrees with the satellite image. I disagree with poitsplace that there is a linear distribution of CO2 by altitude, but again this is not a discussed topic. I usually mention Newton as this highlights the issue of convection. The laws of thermodynamics and Newtonian physics always apply. The difficulty is the fluid flow that must be applied to understand what is going on in the atmosphere. The gases have mass and momentum. The gasses have heat. The gasses obey the basic laws such as PV = nrt. Not a simple picture. I was educated as a EE but my specialty is programming. I know enough to not start programming without a very good understanding of the problem to be solved. To me the AGW agenda is without science and exists only in the world of computer models. Most of the models are discussed only in very simple terms and output graphs that have been forced to fit the past but have shown no ability to predict the future.
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Post by hilbert on Mar 31, 2009 16:53:08 GMT
If the atmosphere didn't absorb IR the "% radiated directly from space from earth" would be far higher and the "% radiated to space from clouds and atmosphere" would be near zero.
It makes a big difference where the IR is emitted from because temperature drops with height in the atmosphere. It seems as though convection carries the heat away from the surface much more than radiation. The surface of the moon in the day is quite hot (even though that means even more radiation is being emitted).
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Post by socold on Mar 31, 2009 23:04:39 GMT
Socold, the statement you made "Because it shows the net flow in and out of the atmosphere rather than internal transfers in both directions." is thermodynamically meaningless. The diagram shows the % incoming solar absorbed and the % outgoing IR absorbed. It doesn't show radiation between the atmosphere and ground or between different layers of atmosphere, the whole lot is bundled into the %s. I never said there is net backradiation. I have said that there is backradiation: That equilibrium state involves the surface radiating more IR upwards than it absorbs from the atmospheric emission. If the surface wasn't absorbing IR from the atmosphere the surface (and atmosphere) would be at a cooler equillibrium state. Exactly. Subtract the atmosphere->surface amounts from the surface->atmosphere amounts: Heat is flowing from the surface to the atmosphere. Because the energy the Sun absorbs from the Earth is miniscule. Wheras the backradiation surface absorbs is not. In the case of backradiation it's absorption by the surface results in a significantly warmer surface than if the surface didn't absorb backradiation. I agree. Heat flows from the warmer surface to the cooler atmosphere. You misunderstand the NASA diagrams. They are fully compatible with the K&T diagrams. You need read no further than the very page the "NASA diagram" came from to realize this: "The greenhouse effect is due mainly to water vapor in the atmosphere. This effect is enhanced by carbon dioxide, methane and other infrared-absorbing gases." You'll also see a familiar "NASA diagram" here: earthobservatory.nasa.gov/Features/EnergyBalance/page6.phpBut look: "Because greenhouse gas molecules radiate heat in all directions, some of it spreads downward and ultimately comes back into contact with the Earth’s surface, where it is absorbed. The temperature of the surface becomes warmer than it would be if it were heated only by direct solar heating. This supplemental heating of the Earth’s surface by the atmosphere is the natural greenhouse effect." And under that there is another energy budget diagram (again showing the same thing in a different way) with a big red arrow labelled "back radiation". Hmmm who are you kidding? Yourself but not me.
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Post by socold on Mar 31, 2009 23:15:28 GMT
Gridley Notice the date on the jpg that was supplied it is 2003. For some reason there is very little discussion of the magic gas CO2 other than it is always well mixed, which disagrees with the satellite image. No it doesn't, look at the scale.
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Post by socold on Mar 31, 2009 23:16:48 GMT
If the atmosphere didn't absorb IR the "% radiated directly from space from earth" would be far higher and the "% radiated to space from clouds and atmosphere" would be near zero.
It makes a big difference where the IR is emitted from because temperature drops with height in the atmosphere. It seems as though convection carries the heat away from the surface much more than radiation. The surface of the moon in the day is quite hot (even though that means even more radiation is being emitted). The reason convection carries away more heat is that backradiation is so strong. If there was no backradiation, radiation would transfer about 390wm-2, which easily overwhelms convection.
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Post by socold on Mar 31, 2009 23:18:01 GMT
This assumes greenhouse gases do cause warming, which Kiwi keeps disagreeing with. Ie Lindzen disagrees with Kiwi. So I don't see why this reply is aimed at me.
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Post by hilbert on Apr 1, 2009 0:22:37 GMT
If the atmosphere didn't absorb IR the "% radiated directly from space from earth" would be far higher and the "% radiated to space from clouds and atmosphere" would be near zero.
It makes a big difference where the IR is emitted from because temperature drops with height in the atmosphere. It seems as though convection carries the heat away from the surface much more than radiation. The surface of the moon in the day is quite hot (even though that means even more radiation is being emitted). The reason convection carries away more heat is that backradiation is so strong. If there was no backradiation, radiation would transfer about 390wm-2, which easily overwhelms convection. So, why is the moon, during daylight, so much hotter than the surface of the earth?
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Post by nautonnier on Apr 1, 2009 2:18:47 GMT
Errrm 1. you are completely ignoring convection - as you normally do
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Post by nautonnier on Apr 1, 2009 2:21:48 GMT
If the atmosphere didn't absorb IR the "% radiated directly from space from earth" would be far higher and the "% radiated to space from clouds and atmosphere" would be near zero.
It makes a big difference where the IR is emitted from because temperature drops with height in the atmosphere. It seems as though convection carries the heat away from the surface much more than radiation. The surface of the moon in the day is quite hot (even though that means even more radiation is being emitted). The reason convection carries away more heat is that backradiation is so strong. If there was no backradiation, radiation would transfer about 390wm-2, which easily overwhelms convection. Have you got a cite for 'back radiation' from CO 2 its mechanism and strength?
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Post by kiwistonewall on Apr 1, 2009 10:57:13 GMT
Back scatter: No such thing from a thermodynamic standpoint.If the atmosphere is warmer than the ground, it will radiate downwards in the black body radiation power curve appropriate to Temperature. (NOT just the "greenhouse" gases.) There is nothing that will stop that radiation occurring - it is a property of Temperature. hyperphysics.phy-astr.gsu.edu/hbase/thermo/absrad.html#c1On annual/global average, it doesn't happen, and can be ignored. "Greenhouse" gases absorb & emit at certain narrow frequencies- this moves radiation around, and creates some spectral anomalies, but no change to the radiative transfer. At least, there is no mathematical formula ever put forward dependent on anything else but T. The "greenhouse" enhanced temperature of Earth depends on T. Remove the atmosphere, and you have a big problem! Remove the CO2 & you stop photosynthesis. Double CO2 will make the atmosphere a tiny bit more dense (and that will have a tiny effect). Thick atmosphere = warmer planet. Thin atmosphere=cooler planet. Composition is largely irrelevant. Remember the thermodynamic rules: 1. Heat moves from HOT to COLD- Never the other way unless you have a heat pump. 2. Anything the absorbs radiation as easily emits radiation. (Black surfaces are good absorbers and emitters of heat. When exposed to warmth, they absorb. In the cool they emit. When they are at the same temperature as their surroundings they are "back scattering" - but that is never considered in thermodynamic equations. ============================================= There is no evidence that CO2 has a special function in perverting the course of Thermodynamics. It is total nonsense to talk (as the AGW proponents do) of the "greenhouse effect" being caused only by greenhouse gases. Spectral bite in Earth's outgoing radiance is simply energy absorbed by CO2 being transferred to more abundant water and radiated out as a peak. If the AGW theory had any basis, there would be a massive bite in the H2O spectrum, but there is a peak instead. The Greenhouse effect is largely unaffected by CO2. No forcing. IPCC & any scientist who says otherwise is just as ignorant as the "genuine experts" who accepted Phlogiston. That was the ruling consensus for years! ;D
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