This is yet another of the many socks of Doug Cotton (which may itself be an alias, for all I know).
Anyway, I'm utterly bored with moderating his stuff now. So, the rules, specifically for Doug C:
1. Yes, you get your own rules and they are stricter than for everyone else. Cry me a river.
2. You can only post under one name, and that name is Doug Cotton. No hiding under fake names.
3. Usually, you should stay on topic. You should only go of topic if you're bringing up a new idea.
4. Long comments that only repeat what you've said elsewhere aren't acceptable. Simply link to what you've said elsewhere.
5. Be polite and have some self-respect. Hint: prefixing your comments with "I'm not going to waste my time here" is not only impolite, its also pathetic.
This blog consists of comments from my real blog, http://scienceblogs.com/stoat/, which I don't want to publish there. Plus some other stuff convenient to place here. And its becoming a convenient place for me to dump my comments on other blogs so I can find them again.
It's not hard to understand the state of thermodynamic equilibrium. As explained in my book, start by imagining two horizontal planes of molecules with (PE + KE) the same for every molecule. If the planes are separated by the mean free path or less, then a molecule moving down from the top plane gains KE and loses the same amount of PE. The opposite happens for a molecule moving upwards between the planes. The important point is that, when either of these molecules collides with a molecule in the other plane it has gained or lost just the right amount of KE such that it has the same KE as the molecule in the plane it reaches. And because the KE matches in all collisions there is no propensity for further dispersion of KE (conduction, diffusion or convection) and thus we have the state of thermodynamic equilibrium,
ReplyDeleteOnly in a horizontal plane is there no change in KE during free path motion and so temperature does indeed level out in a horizontal plane, but not in a vertical plane. This was what Loschmidt visualised back in the 19th century and he was right. All attempts to prove him wrong (like Robert Brown's) don't demonstrate an understanding of thermodynamic equilibrium and the fact that, if you combine two systems you just get a new state of thermodynamic equilibrium with a new temperature gradient, but certainly no perpetual circulation of energy.
You all need to come to grips with the process which the Second Law describes, and how it applies to all forms of energy and equilibrium. (Hence it is also the Second Law which tells us why there is a density gradient.) Then you need to understand entropy and the state of thermodynamic equilibrium (which includes mechanical equilibrium) and why that state must have no unbalanced energy potentials.
Note that the Second Law applies to every independent process or to a sequence of dependent processes. An example of a "net" effect is seen in a siphon where water flows up the short side (the first dependent process) and down the longer side (the second dependent process) and so entropy does increase for the combination of processes or participating systems. But they must be dependent processes or as stated here be "participating systems." If you cut the siphon at the top you no longer have two participating systems that are inter-dependent.
Now, the electromagnetic energy in back radiation can only be used for a part of the surface's own quota of outward electro-magnetic radiation. If its EM energy were converted to thermal (kinetic) energy in the surface then that KE could escape by conduction, evaporation etc and there is no subsequent dependent radiation process. So the first process transferring thermal energy from cold to hot can't happen, even if those in Climatology Carbonland think it can. All one-way radiation only ever transfers thermal energy from hot to cold because there are no molecules involved and being affected by gravity. Hence the only way the temperature gradient builds up in a high troposphere (as for Uranus and Venus) where no significant direct solar radiation heats a surface (if any) is from the upper colder regions to the warmer regions by non-radiative heat transfer which can "creep" up the temperature plot if thermodynamic equilibrium has been disturbed with new energy at the top, and now needs to be restored by spreading that new energy in all accessible directions away from its source.
ReplyDeleteWilliam and others:
All alarmist comments are based on IPCC documentation, and that documentation says the Earth's surface would be 33 degrees colder without greenhouse gases. Water vapour is thus meant to be doing most of that warming from about 254.5K to about 287.5K to the nearest half degree.
But in calculating the 254.5K temperature they fail to alter the albedo which, according to their energy diagrams includes 30% of solar radiation reflected back to space by those clouds which would only exist if the greenhouse pollutant, water vapour actually existed. But they have assumed it doesn't in this scenario. So they incorrectly use only 70% of a quarter of the solar flux (1365W/m^2) and then they also assume incorrectly that emissivity is 1.0000, and so then then incorrectly get that temperature of 254.5K in Stefan-Boltzmann calculations.
The ramifications of this enormous oversight are huge, because if they had not reduced the radiation by 30% due to the clouds that don't exist. and if they had used a more realistic emissivity for a dry, rocky planet - say 0.88, then they would have got a temperature of 287.58K which is close enough to what is the existing mean temperature with GH gases that are thus doing no warming at all. I would add that the emissivity is more likely to be lower than 0.88, this giving a higher temperature above 290K, and so GH gases are cooling Earth.