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Simple Question About AGW

Slimething said:
Show me your math.
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Show my math? I did none; I just reported what I believe to be the predominant theory of Venus' planetary evolution. I'm an electrical engineer, not a planetary scientist; I generally trust experts in planetary science to get their math right, particularly given how long Venus has been studied scientifically. I would hope a planetary scientist with no training in engineering wouldn't question how I terminated my DDR2 bus! :)
 
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CapelDodger said:
That's a big part of the story. The whole story (as ever) isn't quite as simple as that ... :)

Some of the energy captured is converted to kinetic energy within the molecule - its component atoms oscillate more. If it's in collision with another air molecule while in that state it can transfer some of that kinetic energy directly. So it's a bit more complicated, but it's all calculable.
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Cool; I didn't know about that mechanism. I owe you a pint.

The environment is very different, though, because nebulae have very weakly interacting particles whereas the atmosphere has strongly interacting particles. It's a real crush down here :).
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Yeah, you're right. I was just using a nebula as an example of extremely rarefied gas still creating a measurable absorption effect.
 
zeusbheld said:
which could be construed to demonstrate GW (although my experience as a non-gardener is... weather changes often)... but NOT rigorously... and i fail to see how 'getting out more' will put the A in AGW.
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Obviously the benefit won't be immediate, but at least over a few years they'll get over the idea that it's not warming, that all stopped in '98, doncha know.

The "A" comes from no credible alternative, despite much effort being expended on the search. I see scientists who claimed there'd be no warming now touting reason and after reason for it, all of them resolutely not AGW. And that's it.

There's no contest. CO2 is materially affecting the climate.
 
a_unique_person said:
I could be wrong here, but PV/T is a description of what is happening, not why.
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You are right. The full law is PV=nRT but the nR are both constants that drop out when comparing the same system in two different states. There is no prediction therein other than that the three variables are correlative and vary as described. I was reacting to Capel Dodger's ridiculous assertion. Maybe he should explain why we're all floating on magma if pressure does not translate to heat.
 
Round Robin said:
Show my math? I did none; I just reported what I believe to be the predominant theory of Venus' planetary evolution. I'm an electrical engineer, not a planetary scientist; I generally trust experts in planetary science to get their math right, particularly given how long Venus has been studied scientifically. I would hope a planetary scientist with no training in engineering wouldn't question how I terminated my DDR2 bus! :)
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I do have a confession to make now that I've cooled down a bit. I lost my temper. My math is correct but all it does is show that the pressure on Venus does account for some of the surface temperature. The weakness in the calculation is that, at those pressures, CO2 or any gas would not act in the ideal manner we theorize for all gases near our ambient pressure.

Moreover, I made a mistake in my thinking in that Beer's Law would negate a greenhouse effect on Venus. It would not. Whereas it would effectively block out all the IR from reaching the surface, it would also tend to insulate IR generated by reradiation of other absorbed wavelengths that penetrated to the surface. So, there. I am chastened and contrite.

However, the point still stands that the pressure on Venus would contribute mightily to the surface temperature.
 
Slimething said:
Really? How did they get around Beer's Law (saturation effect), 96+% CO2 and 90 atm worth of heat? I could be wrong here but that doesn't seem to be correlative to the situation on Earth. Show me your math.
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A "runaway effect" implies saturation, or exhaustion of a necessary resource, at some point in time.

Do the math, for a real environment.

Another thing that's been bugging me : are you under the impression that pressure creates heat?
 
Slimething said:
Really? Any warming? Even non-gas-mediated warming? Funny. How is the troposphere to know?
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There's a non-linear relationship (driven by water-vapour and its effect on the lapse rate) between surface temperature and the temperature mid-troposphere which means that the temperature gradient is inversely correlated with the surface temperature. Which means that when the surface warms the troposphere has to warm more, to reduce the gradient.
 
Round Robin said:
Cool; I didn't know about that mechanism. I owe you a pint.
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Fuggedaboudit. I've learnt a hell of a lot since I've got into this thing.

Yeah, you're right. I was just using a nebula as an example of extremely rarefied gas still creating a measurable absorption effect.
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It's a good example since it does isolate the absorption/emission effect, and isolating an effect is generally regarded as a good thing in science. Eliminate the other variables, to the extent that you can.

These demands for experiments in the real atmosphere (followed by rejection of Venus's very real atmosphere as an example) are going in exactly the opposite direction. Cramming as many variables into an experiment as you can "just to make sure" is not good scientific thinking, to my mind.

I'm still waiting on the specs for Dr Imago's box.
 
CapelDodger said:
Another thing that's been bugging me : are you under the impression that pressure creates heat?
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Yes, I am. I find that you'll find that little quirk in most scientists. If you keep volume constant and increase pressure, you get a temperature increase. Is that news to you?
 
CapelDodger said:
There's a non-linear relationship (driven by water-vapour and its effect on the lapse rate) between surface temperature and the temperature mid-troposphere which means that the temperature gradient is inversely correlated with the surface temperature. Which means that when the surface warms the troposphere has to warm more, to reduce the gradient.
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Perhaps you don't understand English. A non-gas-mediated warming. As in no CO2, no water vapor, no helium, no argon, etc. Get it yet? :confused:
 
Slimething said:
Yes, I am. I find that you'll find that little quirk in most scientists. If you keep volume constant and increase pressure, you get a temperature increase. Is that news to you?
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How would that work? You can't increase pressure and keep volume constant. The only way to do it is to increase the temperature. QED.
 
Slimething said:
Yes, I am. I find that you'll find that little quirk in most scientists. If you keep volume constant and increase pressure, you get a temperature increase. Is that news to you?
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I think you misread CapelDodger's question. He asked about heat; you answered about temperature.
 
Slimething said:
Yes, I am. I find that you'll find that little quirk in most scientists. If you keep volume constant and increase pressure, you get a temperature increase. Is that news to you?
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If you compress a gas it will get hotter. The work expended in compressing it is converted into heat. Leave it compressed and that heat will dissipate. Venus's atmosphere has been compressed long enough for all the heat of its original compression to have dissipated long ago.

Pressure does not create heat.
 
Slimething said:
Perhaps you don't understand English. A non-gas-mediated warming. As in no CO2, no water vapor, no helium, no argon, etc. Get it yet? :confused:
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Increased insolation is not a gas-mediated warming. The impact on the surface to mid-troposphere temperature gradient is gas-mediated, but that's the atmosphere we have to live with.
 
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