Simple Question About AGW

[CapelDodger]

I think you misread CapelDodger's question. He asked about heat; you answered about temperature.

It all comes down to heat in the end .

"Can't avoid, can't reverse,
Energy Death of the Universe"

(From Energy Death by the short-lived 70's pub band Energy Death. yeah, we all saw where that was going, but at least they got a cocktail named after them.)

 

[jsfisher]

If you compress a gas it will get hotter. The work expended in compressing it is converted into heat.

Temperature of a gas is a reflection of its heat content per unit volume. Compress the gas, and the temperature goes up (it gets hotter) because of greater heat per volume and not because of any additional heat.

 

[Slimething]

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.

That's a real diamond of a thought. You must have missed that class.

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.

You must have missed that class also. A little thought experiment for you. If you have a compressed gas cylinder at room temperature and you knock the valve off with a sledge, will the cylinder heat, stay the same or cool? Duh. There goes your half-baked argument.

I told you to study up on your thermo, yes? Why didn't you do it before making a complete fool out of yourself?

I missed that gem; I was focussed on my original target . Set 'em up, knock 'em down.

QED.

 

[Slimething]

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.

You just can't escape that circle, can you? Why do we even try?

 

[mhaze]

Originally Posted by David Rodale
The troposphere is not warming as dictated by AGW hypotheses.

​

Mid-troposphere warming is dictated by any warming, so this claim is tantamount to a claim that there's been no warming.

IPPC ch. 9, p. 675, figure 9.1.

Distinctly differing atmospheric warming signatures.

which is obvious if you think about it.

 

[bobdroege7]

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.

We are all floating on magma because the big ball of earth is about 1% uranium, which is radioactive and the heat of that radioactive decay is what produces the heat. Which produces the magma.

 

[CapelDodger]

You must have missed that class also. A little thought experiment for you. If you have a compressed gas cylinder at room temperature and you knock the valve off with a sledge, will the cylinder heat, stay the same or cool? Duh. There goes your half-baked argument.

Irrelevant. Venus has never decompressed. If you don't knock the valve off the cylinder any heat generated during compression will dissipate. Entropy increases. Venus's atmosphere accumulated long ago, and the heat of compression has dissipated.

I told you to study up on your thermo, yes? Why didn't you do it before making a complete fool out of yourself?

Cute.

So are you still under the impression that pressure creates heat?

 

[David Rodale]

I could be wrong here, but PV/T is a description of what is happening, not why.

Pierrehumbert has a discussion on Venus even I can understand in his free, online textbook.

http://geosci.uchicago.edu/~rtp1/ClimateBook/ClimateVol1.pdf

Page 15, chapter 1.4

Venus Express:
http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=33010

You cannot understand the Venusian weather and atmosphere by comparing them to Earth's. Scientists are unable to explain some of the more extreme atmospheric phenomena that take place on Venus. For example, the planet only rotates once every 243 Earth days. However, in the upper atmosphere, hurricane-force winds sweep around Venus, taking just 4 Earth days to circumnavigate the planet.
The surface of Venus also baffles scientists. The oldest craters seem to be only 500 million years old, which may indicate that the planet behaves like a volcanic pressure cooker. On Earth, the constant, steady eruption of volcanoes and the shifting of the Earth's surface, causing earthquakes, ensures that the energy released in the Earth is dissipated gradually. This probably does not happen on Venus. Instead, pressure builds up inside the planet until the whole world is engulfed in a global eruption, resurfacing the planet and destroying any craters that have formed. This probably happened last, 500 million years ago and so accounts for the lack of older craters. Today, there is a strong relationship between the surface and the atmosphere. Is there any similarity between the ocean-atmosphere relationship on Earth and the surface-atmosphere relationship on Venus? Venus Express supplies scientific data that could shed light on both of these mysteries.

 

[Round Robin]

You must have missed that class also. A little thought experiment for you. If you have a compressed gas cylinder at room temperature and you knock the valve off with a sledge, will the cylinder heat, stay the same or cool? Duh. There goes your half-baked argument.

P -> Lower
V -> Unchanged
n -> Lower
R -> Constant
T -> Lower

Since n (moles of gas) changes, I am not sure that your thought experiment is representative of the situation described.

Also, are you assuming that Venus is a closed system?

 

[a_unique_person]

We are all floating on magma because the big ball of earth is about 1% uranium, which is radioactive and the heat of that radioactive decay is what produces the heat. Which produces the magma.

I have wondered why it is so hot after so long.

 

[CapelDodger]

We are all floating on magma because the big ball of earth is about 1% uranium, which is radioactive and the heat of that radioactive decay is what produces the heat. Which produces the magma.

Somethig that Kelvin was unaware of. Based on thermodynamics alone he calculated Earth's age at about twenty million years, as I recall. That's heat from deep within the core, not from a thin skin of atmosphere.

 

[CapelDodger]

You just can't escape that circle, can you? Why do we even try?

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.

 

[Slimething]

We are all floating on magma because the big ball of earth is about 1% uranium, which is radioactive and the heat of that radioactive decay is what produces the heat. Which produces the magma.

You can't be serious. How does that 1% know to stay in the magma? Nowhere near that concentration has been found in igneous rock. That concentration of uranium would have every mineral prospector this side of hell in Hawaii, Mt. St. Helens, Iceland, etc. Check your facts.

 

[Slimething]

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.

So, to turn the question around to you, if there is warming, why no troposhpere hotspot? You can't have your cake and eat it too.

 

[Slimething]

I have wondered why it is so hot after so long.

Because bobby's wrong. There is not 1% U in the magma.

ETA: Check this out. Bobby, your astronomer parent would not be proud.

 

[Slimething]

P -> Lower
V -> Unchanged
n -> Lower
R -> Constant
T -> Lower

Since n (moles of gas) changes, I am not sure that your thought experiment is representative of the situation described.

Also, are you assuming that Venus is a closed system?

Yes, one of the assumptions I made. That the atmosphere would expand infinitely to render 1 atm. Good spot. How would you have done it?

 

[Slimething]

Irrelevant. Venus has never decompressed. If you don't knock the valve off the cylinder any heat generated during compression will dissipate. Entropy increases. Venus's atmosphere accumulated long ago, and the heat of compression has dissipated.

That's not the point! You really are thicker than a brick! When you compress a gas, not all the heat goes away a work. The pressure heats the surface. Get that through your skull, if you possibly can. There is heat from pressure. Got it? The pressure is doing work on the planet's surface. Just like the Earth's atmosphere is doing work on your body right now. If that pressure goes away, you would be cooler. The heat has to go somewhere.

So are you still under the impression that pressure creates heat?

If we share the same definitino of heat (Q) as being TdS, no. The heat is latent until decompression. Then, TdS is loose. The heat is stored. Hence, if one were to calculate the temperature contributed by the 90 atm, it would be fairly large.

Nice dodge.

 

[bobdroege7]

Really? Is your Daddy home?



Did I say that? No, no, I didn't. Obviously an intelligent offspring of an astronomer would be able to conceive that Venus without its present atmosphere would be a different kettle of fish altogether, yes? Perhaps not. Take my word for it.



How do you get that the pressure of a planet dictates the composition of the atmosphere? The Earth is at 1 atm and it's got lots more than He.



Time to talk to Dad again, sonny.

First of all, we are not school kids on the playground so leave the bullying at home.

My point is you are applying the ideal gas law in an incorrect method.

Second, the temperature of a planet has something to do with the atmospheric composition. As you know the earth is much warmer than 8K and has little He. I didn't post that the pressure causes the temperature.

By the way, in a blatant appeal to self authority, I have taught college chemistry, so I might know something about the Ideal gas law. And here's the point, P1V1/T1=P2V2/T2 applies to different states of the same system, where you can keep the n constant, such as in the piston and cylinder problems you no doubt are familiar with.

Plugging in the different pressures for Earth and Venus and solving for temperature gives you an erroneous result.

 

[bobdroege7]

Because bobby's wrong. There is not 1% U in the magma.

ETA: Check this out. Bobby, your astronomer parent would not be proud.

The internal heat of the planet is most likely produced by the radioactive decay of potassium-40, uranium-238 and thorium-232 isotopes. All three have half-life decay periods of more than a billion years.[40] At the center of the planet, the temperature may be up to 7,000 K and the pressure could reach 360 GPa.[41] A portion of the core's thermal energy is transported toward the crust by Mantle plumes; a form of convection consisting of upwellings of higher-temperature rock. These plumes can produce hotspots and flood basalts.[42]

So maybe I'm wrong about the about 1% part but the rest is true.

Kindly leave my recently departed parent out of this really you are a heel.

 

[bobdroege7]

You can't be serious. How does that 1% know to stay in the magma? Nowhere near that concentration has been found in igneous rock. That concentration of uranium would have every mineral prospector this side of hell in Hawaii, Mt. St. Helens, Iceland, etc. Check your facts.

Right, I was wrong. Actually the concentration is 2-4 parts per million. Still enough to cause the heating of the planet's internals.