About the lapse rate:
It gets colder as you go to higher altitudes. That’s because rising air expands and thus cools and falling air does the reverse. If the upper air is hotter than the normal lapse rate would dictate it is called a temperature inversion and there is little circulation, if colder a lot of circulation. Since the earth’s atmosphere is heated from below as sunlight is absorbed, temperature inversions usually do not last long.
How hot an object becomes in the solar system depends on how close it is to the sun. The albedo or reflectivity of the object has nothing to do with it. Black things warm and cool faster but approach the same equilibrium as white things. I’ve been over this recently. But I note with dismay that they are still wanting to do something to make the upper atmosphere a little white so as to reflect sunlight and cool us down. That might work for a few years as the atmosphere equilibrates. The shadow of a cloud is cooler than direct sunlight, as all know. But at equilibrium that would make us a lot hotter.
If you look at Venus, it’s very pretty. It’s a pure bright white. It’s albedo is a lot higher than that of the earth. And it’s hotter, being nearer the sun. But its surface is hotter than even its proximity to the sun would make it. The high opaque clouds that make it so pretty, and which are pretty much the same sort of thing that certain people would like to put high in our sky, are more or less in equilibrium with the sun. The lapse makes the surface hotter.
Were one in a merry mood, one might suggest doing that to Mars to warm it up for us. Or one might suggest that a really stupid advanced civilization on Venus did that in order to cool their planet by the same logic that those who for reasons that elude me use as their rationale. By really stupid, I mean a civilization much like ours since the scheme does seem to be getting serious attention.
Not being in a merry mood I penned (all right – word processed) the following letter to the publisher of the most recent article I read. Having failed to win attention with reason and charm, I am trying to sting them awake with sarcasm. Also somebody has suggested that difficult fonts are easier to learn from. I usually use Times New Roman 14 point to make it easy to read. This time I used a smaller san serif font. (Elephant, but I can't reprodeuce that here.)
The Alpine meadow I mention in the letter is actually rather warmer than the surface of Venus would be if albedo determined temperature, but not by much. Rather than give up my figure of speech I decided to allow a little greenhouse effect.
The heat of the surface has been noticed to be anomalously high on Venus. They attribute it to runaway greenhouse effect. Greenhhouse effect has nothing to do with a real greenhouse, which keeps thing warm by shutting out the wind and reducing convection. The “effect” is thought to be due to the fact that light can go through CO2 easily but infra red is absorbed. Without going again into the details, suffice it to say that since the atmosphere of Venus is opaque to light there must be only a little greenhouse effect. That said, here is my letter:
ECONOMIST
111 West 57th Street
New York, NY 10019
Dear Sir:
Re: vol. 397 no. 8707 page 99 “Lift-off” November 6, 2010
Sure making the sky opaque will cool the earth at equilibrium; that’s why the surface of Venus is the temperature of an Alpine meadow in spring rather than the searing inferno the laws of physics require.
M. Linton Herbert
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