(published on 10/22/2007)
(published on 08/23/2009)
(published on 11/04/2010)
The water vapor molecules will very quickly trade energy with other molecules in the air, so that each region will have a single temperature. Perhaps you're getting at another related effect. Say that the water vapor pressure is high enough so that at say 90°F liquid water is in equilibrium with the vapor. That means that the rates of water molecules leaving the liquid to the vapor and of the opposite process just balance each other. We say that the relative humidity is 100%. What happens if to a tiny drop of liquid water? It has a lot of surface area, so on the average its molecules aren't as well stuck to each other as they would be in a large body of liquid. So it's easier for molecules to leave the tiny drop. It will usually evaporate, even though the relative humidity is 100%. In that sense, it almost acts as if the temperature of the tiny drops were a bit higher than it really is.
If the relative humidity is a bit over 100%, then the rate at which water comes in to the liquid from the vapor is bigger than the rate at which it evaporates from a big body of liquid. So water will condense out from the vapor. If, however, there are only very little drops of liquid then they will evaporate for the reasons we gave above. This is an unstable situation- it "wants" to rain, but can't find a way to form stable raindrops. In those circumstances, rain can be triggered by introducing some little nucleation particles that make it easier for liquid drops to form.
(published on 01/08/2015)