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Post by socold on Apr 6, 2009 21:04:15 GMT
%wise, about 94% of the greenhouse effect on Earth is non-greenhouse gases. (From calculating the area of Earth's bb radiation which is intercepted by non-greenhouse gases) the lunacy marches ever onwards
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Post by icefisher on Apr 7, 2009 4:29:14 GMT
%wise, about 94% of the greenhouse effect on Earth is non-greenhouse gases. (From calculating the area of Earth's bb radiation which is intercepted by non-greenhouse gases) the lunacy marches ever onwards In my opinion accepting as fact that which you cannot understand is the very definition of lunacy. If you think not, I have a bridge you might be interested in.
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Post by FurryCatHerder on Apr 7, 2009 6:52:38 GMT
the lunacy marches ever onwards In my opinion accepting as fact that which you cannot understand is the very definition of lunacy. If you think not, I have a bridge you might be interested in. There are a LOT of things I don't understand. But I don't presume to know more than experts in the field. The basic physics is rock solid -- the more CO2 between the ground and space, the more likely a CO2 molecule is to absorb and re-radiate long wave radiation. That's the "trap the heat" part. Or to keep with this "hat" thing, "run into another hat and not escape as heat."
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Post by icefisher on Apr 7, 2009 7:44:34 GMT
In my opinion accepting as fact that which you cannot understand is the very definition of lunacy. If you think not, I have a bridge you might be interested in. There are a LOT of things I don't understand. But I don't presume to know more than experts in the field. One should not presume anything including what experts tell you. Admitting you have no idea is a fine place to be. That is especially true when an "expert" used car salesman pitches you a car.
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Post by poitsplace on Apr 7, 2009 8:11:01 GMT
In my opinion accepting as fact that which you cannot understand is the very definition of lunacy. If you think not, I have a bridge you might be interested in. There are a LOT of things I don't understand. But I don't presume to know more than experts in the field. The basic physics is rock solid -- the more CO2 between the ground and space, the more likely a CO2 molecule is to absorb and re-radiate long wave radiation. That's the "trap the heat" part. Or to keep with this "hat" thing, "run into another hat and not escape as heat." Yeah BUT...it's already fairly pretty well saturated...already reradiating a lot. Every time it radiates again though there's a good chance that water with it's advantage of being as much as a whole percent of the atmosphere grabbing that radiation and reradiating it outside the spectrum of CO2. It's ALREADY doing this a lot, hence the extra hat analogy. The hat analogy refers NOT to the insulating capability of the hat but the fact that it makes no difference how many hats you wear...if you're not insulated anywhere else. Essentially all of the energy interacting with CO2 is already pouring out around its spectrum. More CO2 at this point is insignificant because any of the extra energy it did snag would still follow the same path. MOST of the energy is radiated outside the spectrum of CO2. Essentially all of the energy captured by CO2 is already shifting to other parts of the spectrum and leaving that way. The minute amount more absorbed energy will be taking the same way out that all the other energy does.
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Post by steve on Apr 7, 2009 10:06:15 GMT
So Mars temperature should be an extra 4.5C warming on top of the 7C, which is 11.5C. So we might expect Mars to have an "average" temperature in the region of 222 Kelvin. You seem to be just confirming what Kiwi said Steve. Average surface temp of Mars is about 227 Kelvin and 5 degrees C more is 43% greater than the 11.5 degrees C you just calculated. So what am I missing here in your post? I'm not agreeing with Kiwistonewall's suggestion (serious or not) that AGW theory says that Mars should be warmer, and I'm saying that his calculations are a bit wrong as well. I am agreeing that you cannot automatically assume that the greenhouse effect on Mars will have an "identical" effect to the greenhouse effect on Earth, as the effect is a function of the temperature profile of the atmosphere in the layers that emit radiation into space, and probably affected by the over-all lower pressure that means spectral lines on Mars will be narrower than spectral lines on Earth (see "pressure broadening") Also, while the O2 and N2 do not emit and absorb much radiation, in earth's atmosphere they act as a thermal mass (along with the effects of the hydrological cycle) that evens out the diurnal cycle.
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Post by steve on Apr 7, 2009 10:25:36 GMT
There are a LOT of things I don't understand. But I don't presume to know more than experts in the field. The basic physics is rock solid -- the more CO2 between the ground and space, the more likely a CO2 molecule is to absorb and re-radiate long wave radiation. That's the "trap the heat" part. Or to keep with this "hat" thing, "run into another hat and not escape as heat." Yeah BUT...it's already fairly pretty well saturated...already reradiating a lot. Every time it radiates again though there's a good chance that water with it's advantage of being as much as a whole percent of the atmosphere grabbing that radiation and reradiating it outside the spectrum of CO2. It's ALREADY doing this a lot, hence the extra hat analogy. The hat analogy refers NOT to the insulating capability of the hat but the fact that it makes no difference how many hats you wear...if you're not insulated anywhere else. Essentially all of the energy interacting with CO2 is already pouring out around its spectrum. More CO2 at this point is insignificant because any of the extra energy it did snag would still follow the same path. MOST of the energy is radiated outside the spectrum of CO2. Essentially all of the energy captured by CO2 is already shifting to other parts of the spectrum and leaving that way. The minute amount more absorbed energy will be taking the same way out that all the other energy does. There are implicit misunderstandings here: 1. Most of the energy in the atmosphere is in the form of classical kinetic energy of molecules (ie. half m-v-squared). Only a small percent of energy is IR. Therefore most of the excitation (and deexcitation) of greenhouse gas molecules is caused by collisions with other molecules. 2. Energy cannot "pour out" of the sides. Kirchoff's theorem says that emissivity and absorptivity of a material at a given waveband balance.
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Post by julianb on Apr 7, 2009 13:13:27 GMT
Steve there are 'implicit misunderstandings' in your final non sentence, can you complete it please?
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Post by steve on Apr 7, 2009 14:12:49 GMT
Steve there are 'implicit misunderstandings' in your final non sentence, can you complete it please? It's correct I think. Maybe an "each other" at the end would help. "2. Energy cannot "pour out" of the sides. Kirchoff's theorem says that emissivity and absorptivity of a material at a given waveband balance each other. The emissivity equals the absoptivity, so if a blob of gas is receiving radiation emitted by blobs of gas around it that are at about the same temperature, then if it is efficiently absorbing this radiation at a particular wavelength it will also be emitting the same proportion of the radiation at the same wavelength.
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Post by jimg on Apr 7, 2009 17:02:36 GMT
Steve, perhaps the sentence should read:
The energy emitted plus the kinetic energy gained by the molecule will equal the energy absorbed?
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Post by steve on Apr 7, 2009 17:08:54 GMT
Steve, perhaps the sentence should read: The energy emitted plus the kinetic energy gained by the molecule will equal the energy absorbed? No. Check out Kirchoff's law of thermal radiation in wikipedia or in a book. I'm obviously not explaining my point clearly enough.
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Post by poitsplace on Apr 7, 2009 17:24:40 GMT
The emissivity equals the absoptivity, so if a blob of gas is receiving radiation emitted by blobs of gas around it that are at about the same temperature, then if it is efficiently absorbing this radiation at a particular wavelength it will also be emitting the same proportion of the radiation at the same wavelength. And once again for the people in the cheap seats...eventually it hits water vapor which is at MUCH higher concentrations and once that happens it spends most of its time in other frequencies that CO2 can't touch. Also, water will evaporate at disproportionately higher rates (an incredibly powerful NEGATIVE feedback) taking much of its energy up as latent heat to whatever altitude would be necessary to make up the radiative imbalance with CO2 (a compounding negative feedback). The world is just dominated by strong negative feedbacks. CO2 should have little effect by its self (nuisance warming) and has much less of an effect on a world covered in water.
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Post by socold on Apr 7, 2009 18:28:03 GMT
And once again for the people in the cheap seats...eventually it hits water vapor which is at MUCH higher concentrations and once that happens it spends most of its time in other frequencies that CO2 can't touch. Also, water will evaporate at disproportionately higher rates (an incredibly powerful NEGATIVE feedback) taking much of its energy up as latent heat to whatever altitude would be necessary to make up the radiative imbalance with CO2 (a compounding negative feedback). Where are your numbers? People who calculate this stuff find significant warming from doubling co2 and net positive feedbacks. If you don't want to rely on calculations from underlying physics, at least don't present an argument feigning to be based on them.
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Post by icefisher on Apr 7, 2009 19:46:41 GMT
And once again for the people in the cheap seats...eventually it hits water vapor which is at MUCH higher concentrations and once that happens it spends most of its time in other frequencies that CO2 can't touch. Also, water will evaporate at disproportionately higher rates (an incredibly powerful NEGATIVE feedback) taking much of its energy up as latent heat to whatever altitude would be necessary to make up the radiative imbalance with CO2 (a compounding negative feedback). Where are your numbers? People who calculate this stuff find significant warming from doubling co2 and net positive feedbacks. If you don't want to rely on calculations from underlying physics, at least don't present an argument feigning to be based on them. So you are merchandising a model that doesn't do any of these calculations but expect anybody who doesn't buy it to prove it by doing the calculations? What do you do for a living? Sell cars?
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Post by socold on Apr 7, 2009 21:07:01 GMT
Where are your numbers? People who calculate this stuff find significant warming from doubling co2 and net positive feedbacks. If you don't want to rely on calculations from underlying physics, at least don't present an argument feigning to be based on them. So you are merchandising a model that doesn't do any of these calculations but expect anybody who doesn't buy it to prove it by doing the calculations? What do you do for a living? Sell cars? One thing I do know is that climate models do include evaporation and latent heat. I don't know the physics well enough to provide numbers. I defer to the multitude of models out there of various complexities from simple radiative-convective models to full blown GCMs. My position is simply that the models handle the physics as well as anyone can. So I become very skeptical when someone uses a few basic terms to imply they can calculate the physics better than the theoreticians. It's like someone saying "the problem with rocket science is thrust vs gravity", which only begs the question - what are they claiming to know that the experts haven't already factored in. Common sense and skepticism should ring alarm bells that they probably don't understand it better than the experts to make such a claim. Ie the argument defies common sense.
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