But they were also bullish when it was $900. Maybe it'll get back up there, maybe it'll die. Who knows?

It's basically the same principle. In the case of the atmosphere, the gravitational pull of the Earth is acting as a compressor, and the lower pressure at higher altitude is the low coil. When the gas expands and rises, the energy of it's temperature and pressure are converted into gravitational potential energy. The only energy lost is the heat radiated to space.

The atmosphere reaches equilibrium where it is pulled toward the Earth by gravity with the same force that the pressure is exerting to push it away. The rotation of the Earth also comes into play, with the air being flung out like a centrifuge.

It depends what apples you want to compare. The fact that it is cooler higher up is a result of the first law of thermodynamics. The pressure of a gas can be used to do work, so it should be counted as energy. These guys did a better explanation of it than I can do: http://www.thenakedscientists.....

  The premise of the greenhouse effect is that the atmosphere absorbs the heat radiating away from the planet leading to an increase in temperature. The atmosphere of Venus doesn't get down to 1 bar until you're 50 km away from the surface. At this point you're above 90% of the mass of the atmosphere, so there simply isn't enough CO2 (or anything for that matter) to absorb the heat being radiated. http://en.wikipedia.org/wiki/A...

If you were to look at a gas giant, the atmosphere probably absorbs a far higher amount of the radiated energy, even though there aren't as many of the "traditional" greenhouse gasses. As you said, the atmospheric temperature of Jupiter probably matches the same correlation for Venus, because it's far enough away from the surface of the planet that it is ruled by the simple physics of gas laws and absorption of radiation.

Biting flies can and do evolve, but they can't say to themselves, "I'd like to bite more zebras, so I'm going to evolve better ways to decide what to land on."

If the flies who could and did land on zebras reproduced at a rate significantly higher than those who didn't land on zebras, then they would evolve. As that hasn't happened (turns out landing on a zebra isn't such a great thing for a fly to do anyway), there has been no evolutionary pressure and the flies haven't changed.

I didn't account for the internal heat in either planet. I'm not sure how much that would affect the model, but in either case it would push toward more greenhouse.

Temperature is lower at higher altitudes simply because it is at lower pressure. It will be the same on whatever planet you want to look at. Looking at the temperature that high up is just misdirection. Obviously if you're higher than most of the atmosphere, the atmosphere won't affect you as much. The light isn't passing through as much CO2 from those altitudes, so it isn't affected as much it.

Condensing both of our conversations into one:
A very simple climate model is here: http://en.wikipedia.org/wiki/G...

An overview of what's included in the models and why is here: http://www.aip.org/history/cli...

Please don't feel bad about imposing. If I can show just one person the light it will be worth it.

Luckily we're not yet at the stage where the H2O is absorbing all the energy leaving nothing for the CO2 to absorb. Both CO2 and H2O (and a bunch of other gasses) contribute to the effect. H2O is especially worrying as higher temperatures increase evaporation rates, which leads to more H2O in the atmosphere, which leads to higher temperatures etc...

I've answered the Venus thing in response to your other comment about it.

Climate models are very complex because the climate is very complex. If it were simple enough for your average well-educated person to use, they wouldn't accurately model what it's doing.

I didn't really look at what the clouds do. I suppose some of it would be reflected, but I'm not sure how to calculate how much.

I arrived at 97% because a black body at 735 K would radiate 7.6 TW. The sun gives Venus 219 GW, so on the whole it must be radiating about that much, thus 97% of the 7.6 TW being radiated by the surface never leave the atmosphere.

I got to 432 K, by changing the temperature until the energy in=energy out, and the temperature was 302.99 K, 432 less than the 735 K Google told me.

Surface area =4*pi*r^2
Area facing the sun = pi*r^2
radiation rate = emmissive rate / distance from sun ^2
emmissive rate = radiation received at earth (assumed 1kW/m2) * distance from sun ^2
Total energy absorbed = radation rate * area facing sun
energy radiated at surface = s-b constant * surface area * T^4
proportion absorbed by atmosphere = (energy radiated at surface - Total energy absorbed)/energy radiated at surface

The climate is a complicated beast. There's never going to be a simple if x then y kind of arrangement. What is simple is that fact that CO2 absorbs infra-red light. We can test that in thousands of labs around the world, like for instance these guys did. The "central conceit" is that CO2 prevents heat from escaping to space, which we can easily prove in any of those thousands of labs. It would be falsified if CO2 for some reason didn't absorb IR radiation.

Yes, but there were giant fucking lizards back then, not people.

Not in a way that will let us stay alive.

There are people making stupid arguments on your side of the debate too. Doesn't mean we should let them decide the course of action.

You conveniently left out the part where I acknowledged that CO2 isn't the only driver of temperature.

It's the gasses that migrate through the cores. The temperatures are determined by the crystal size, which don't tend to move very much.

Yes, the levels of CO2 in the atmosphere are regulated by many different effects. That's one of the reasons that the currently high levels of CO2 are so alarming: we're way beyond what the planet has dealt with before, so we've used up all of the buffer and we're on the way up even faster now.

I agree with the way you're going about this, I read not to long ago that people shouldn't have a right to their opinions if they cannot defend them. I also like this kind of discussion as it gives me a reason to clarify my thoughts.

CO2 is transparent to most of the spectrum, but the part that affect the temperature is the infra-red region. Infra-red radiation causes molecules to vibrate across the axis of bonds (exactly how gets into some really messy quantum stuff.) Lower frequencies will either affect molecules magnetically (such as microwaves rotating water molecules) or simply not have enough energy to interact and get bounced off the molecule without interacting (such as radio waves.) Higher frequencies either excite electrons (such as visible light) or cause bonds to break (UV and higher.) IR is in the sweet spot for causing heat. The range of wavelengths that can cause heating are 700 nm - 1 mm (1,000,000 nm).

CO2 strongly absorbs radiation at around 4,250 nm and 15,000 nm, both of which being right in the IR field. O2 absorbs at 687 nm and 760 nm, right on the edge of the spectrum. N2 does not really absorb at frequencies below 100 nm. Water (for some reason wikipedia doesn't mention the spectrum of water) absorbs very strongly across the whole IR range. Without getting too far into the exact details of quantum interactions, both H2O and CO2 have polar bonds, which interact much more strongly with the electromagnetic nature of light. O2 and N2 are both non-polar, so magnetic interactions do not affect them at all.

Ok, reading through it a little more carefully and doing some more math, I think his error is in confusing two different ideas. You can either look at the planet as a whole, or go in closer to look at what the atmosphere is doing. The temperatures at earth-like pressures are really just a function of the way gas and temperature are dependent in a gas, so I looked at the planets as a whole. Using the data google gave me when I made simple searches like "distance from sun to Venus", simple geometry formula, heat transfer formula from here: http://www.engineeringtoolbox...., and the assumptions that the earth receives 1kW/m^2 of incident sunlight, that the intensity decreases with the square of radius and that both the Earth and Venus are currently close enough to steady state; I found that the Earth's atmosphere absorbes 36% of the radiation going out to space, while the atmosphere of Venus absorbs 97%! The greenhouse effect on Venus is increasing the temperature by 432 K, while on Earth the difference is around 30 K.

Boltzman constant W m2K4 5.67037E-08
        kW km2K4 5.67037E-11
                Venus Earth
Distance from Sun km 108200000 149600000
Radius km 6052 6378.1
Surface Temperature K 735 288
Surface Area km^2 460264736.8 511201962.3
Area facing the sun km^2 115066184.2 127800490.6
Radiation Rate kW/m^2 1.911651252 1
Total Energy Absorbed kW 219966415.1 127800490.6
Energy Radiated from Surface kW 7616732494 199422477.5
Proportion Absorbed by Atmosphere 0.971120633 0.359147012
Temperature without Greenhouse K 302.9941598 257.6808184
Radiated Energy without Greenhouse kW 219966415.1 127800490.6
Temperature Difference K 432.0058402 30.31918159

Who said that we approach truth through statistics? That's a fairly silly way to look at it, every time you do that you run the risk of mistaking correlation for causation.

In addition to the air migrating through the ice; no one ever claimed that CO2 is the only driver of change. Temperature increases lead to an increase in CO2 and increases in CO2 lead to increases in temperature. The feedback mechanism works to amplify any change imposed by another factor.

Also, the highest CO2 concentration I saw on the page you linked was about 300 ppm. We're currently pretty close to 400 ppm, and seeing higher rates of change of temperature than are seen in the ice cores. You can start a feedback loop from either end.

For those of you who want to know the answer, but don't know the math, xkcd once again has your back. http://what-if.xkcd.com/14/

I'd not heard it used in that form before. Thank you for enlightening me.

I've had a quick search, but I haven't found any of those instances, can you elucidate?

The closest thing I've found is talking about the "lag" of CO2 rise compared to temperature rise. This has already been well explained as a sampling error; failing to account for the migration of air through the ice.