RKS,

It's not STATIC pressure which causes the heat which enables fusion to take place. It's dynamic pressure caused by gravitational collapse. If the hydrogen wasn't spinning into the centre with a great deal of kinetic energy then there would be no fusion. You're mistaken to think a gas at rest with respect to the gravitational centre would, under pressure, begin to fuse.

See Wikipedia (or any astronomy reference for that matter)
http://en.wikipedia.org/wiki/Stellar_evolution#Birth_of_a_star

The second part of your argument that we all accept it's pressure which causes gas giants to be hot is also unfounded. A planet like Jupiter is hot for three reasons 1. remnants of the heat generated by gravitational collapse when it was formed. 2. absorbed solar radiation 3. In the case of Jupiter, adiabatic collapse (it's shrinking by 2cm a year, and this releases enough kinetic energy to heat it.

Things get hot under changing pressure, due to work being done on them - i.e. a hand pushing a pump, or gravity pulling something towards itself. They don't stay hot under constant pressure, which would be a violation of Thermodynamics and would make the air in footballs, car tyres and scuba tanks too hot to touch. (e.g. scuba tank at 100 bar should be 100 times hotter?)

"Jupiter, adiabatic collapse (it's shrinking by 2cm a year,"

However can they measure that? A big ruler? And yet they can't find 2 watts per square meter right here on the surface of the earth, equivalent to finding the light bulb in my front room?

Good question, it's all about Jeans Mass (gravitational collapse of gaseous clouds). I know we should take no-ones word for it, but you're taking it to extremes now :)

I admit to becommig hugely disillusioned with science in recent years. I cling valliantly to the hope that at least physics is more solidly grounded in mathematics than man of the others. I've almost got to the stage my parents got when we kids were arguing en masse, slapping all three of us because while clearly somebody was right, somebody was wrong they had no way of telling which because we were all shouting. The slaps made us think twice about how important an argument was in the first place.

TinyCO2,

I think the problem is that science, having exhausted the main avenues of research has moved onto areas where effects can only be seen by having immensely expensive equipment (e.g. LHC) or by processing data to tease out statistical effects.

While the LHC stuff is exciting, it's very lengthy and stop-start, and the results a bit esoteric.

The stats-based stuff is fraught with false-positives and dependent on data quality and length, and ultimately AGW may prove to be one of these false positives.

Making universities cow-tow to industry and govt for their funding over 20 years won't have helped, either.

Don't think me rude, TBYJ, but we must try to keep our language clear, and your spelling of kowtow (or kow-tow if you prefer) repeats the error of many other bloggers and commentators, here and elsewhere.

Kow·tow (kou-tou, koutou)
intr.v. kow·towed, kow·tow·ing, kow·tows
1. To kneel and touch the forehead to the ground in expression of deep respect, worship, or submission, as formerly done in China.
2. To show servile deference. See Synonyms at fawn1.
n.
1. The act of kneeling and touching the forehead to the ground.
2. An obsequious act.

[From Chinese (Mandarin) kòu tóu, a kowtow : kòu, to knock + tóu, head.]

I take the opportunity to remind those whose spelling is erratic that the correct phrase is "to toe the line" and not "tow the line".

Cassio, I will be sure to tow the line on spelling in future and not cow-tow to the spelling zealots. In this way I will be hoisted by my own petard, and have my just desserts - yum!.

Oh gawd, if I have to spell correctly and not make mistakes you'd shut me up entirely... err don't comment on that ;-)

In my defence, I not only have to manage my own flaws but my computer randomly moves my text cursor about the place and I can start typing anywhere or miss letters out.

RKS is not going to be at all happy with what we did with his thread.

RKS, sorry to see you return with the old anger, I was hoping we'd stick to the science.

Where do you think the energy comes from to energise these gas molecules?
Is the earth's gravity a perpetual motion machine?

The gas molecules are energised exactly as predicted by the gas laws - unless of course you think that kinetic energy somehow does NOT energise the gas molecules.

Let me rephrase:

Where does the kinetic energy come from to energise the gas molecules?
What imparts this kinetic energy to the molecules?

Nikolov and Zeller contend that the temperature of a planet was not dependent on the rate of rotation. It is though. That renders their formula invalid on a fast-rotating planet. IMHO, of course.

Personally I contend that a still atmosphere in the absence of external radiation will be isothermal. But that has not a lot to do with the earth.

RKS,

Charming as your insults are, let's stick to the science.

If I increase the pressure of a fixed volume of gas I increase it's kinetic energy [ie I impart kinetic energy to the gas molecules], which will remain constant as long as the gas pressure remains constant. The formula says it all!

We're getting close.

You have a sealed box, with a gas at a certain temperature and pressure.
You have increased the pressure and thus increased its kinetic energy, very good.
No disagreements here, all according to the laws of physics.

How exactly have you increased the pressure? You've turned on an electric pump, or pushed in a manual pump, or otherwise collapsed the box using energy. You haven't increased that pressure and temperature for free. The only way of increasing the pressure inside the box (apart from adding more molecules) is to compress it into a smaller volume, which involves the expenditure of energy. You have to push the molecules (which want to expand through entropy) into a smaller space, this means spending energy.

It's this energy which heats the gas. It doesn't come from the 'pressure'. Both the increase in pressure and the increase temperature is coming from the work you did compressing the gas. This is what the Ideal Gas equation is telling us - that pressure and temperature are flip sides of the same coin - they are effects of energy, a way we measure energy, but not a source of energy itself.

Temperature is a measure of 'kinetic energy per volume of space'. Pressure is a force produced when the molecules bash that kinetic energy against the sides of the box. The ideal gas laws tell us temperature and pressure are aspects of the same thing, not that one is the driver of the other.

But also remember that the Ideal Gas law is ideal because it ignores other ways that the gas in the box can change temperature. The box is assumed to be completely insulated. In the real world, you would compress your gas and observe the temperature and pressure go up and you could conclude that the gas laws are wonderful, so you would go out for a drink at the pub.

You'd tell your friends that you converted the energy in your arm into temperature in a gas, and they would adore you as a god.

The next day you would come back, and you would be startled to see that the temperature had fallen, in fact almost right back to where it was before you compressed the gas. You check the pressure reading - that has fallen too. You check for leaks, but there are none. What on earth has happened?

You check the IR cameras you sneakily installed to watch the experiment. The box was glowing hot after the experiment, and as the night went on, it cooled. Energy was escaping through radiative heat from the surface of the box. Overnight, a great deal of the extra kinetic energy was transferred from the gas molecules to the box molecules, which were only too happy to radiate it at IR wavelengths out into the room.

Back on the earth. Atmospheric air under pressure near the surface does not have any work done on it - gravity has already collapsed it as far as it can. The air isn't any hotter than the mountains it surrounds. Any extra kinetic energy that being compressed might have given it has long ago dissipated in radiative heat, just like the cold pressurised air in your morning box. Gravity can only give it more kinetic energy if it has lost potential energy, i.e. it has fallen in a gravitational field. It CANNOT continue to heat the air against radiative loss indefinitely, that's not how potential energy works.

A static pressure cannot induce a static temperature. A change in pressure can induce a change in temperature, but that temperature will subsequently fall as it radiates away, and only by further compression could be heated again.

Something for you to ponder between thinking up new insults.

Regards.

First, scientists can be wrong. Whenever two disagree, at least one is wrong. it is no use bringing argument from authority into it. Rotation makes a difference. I don't know how much, but when some person of whatever qualifications comes up with a formula which omits rotation, I suspect he is mistaken.

Eschenbach thinks N&Z are curve-fitting with their chosen parameters. He may be right.

TBYJ gives a clear explanation of what the ideal gas law says. I am not clear at all as to how it works in the absence of 'work done' but I reckon a non-insolated atmosphere will all go to the same temperature and on a sunlit planet the surface will heat the gas, inducing convection. But when there are GHGs and three-state H2O, and rotation and tilt, those things dominate what happens to the sunlight.