Quote:
Originally Posted by Ivan Viehoff
That's the Bad Meteorologist's Number One Error. See http://www.ems.psu.edu/~fraser/Bad/BadClouds.html
In sum, it's got nothing to do with the air. Air does not have a "capacity" for holding water vapour. If you have an evacuated flask and put some liquid water in it, a characteristic amount of water vapour will evaporate above it at a given temperature. Add some air, and it won't make any difference to the amount of water vapour above the liquid in the flask. Cool it down, and some of the water vapour it will condense. The presence or absence of air will make no difference to the quantity. |
Meh, you’re splitting hairs. The temperature of the water vapor is directly determined by the temperature of the air around it. If it were any different it would soon equalize due to the constant exchange of energy in both directions. The temperature of the air therefore *does* determine how much water vapor is present, and that’s all that is essential to understanding the explanation.
If you wanted to extend that and explain why the temperature of the air is important more would be required.