09-27-2015, 07:21 AM
If you follow a rising parcel of air, it eventually forms a cloud when it cools enough for condensation to form. Assuming a relatively normal lapse rate (the rate at which temperature decreases as altitude increases) the rising air usually stays cooler than the surrounding air and keeps rising. When the condensation starts at cloud base, the rate at which the rising air cools due to expansion is reduced because of the release of the latent heat of vaporization of the water it formerly carried, which now exists as water droplets, so the updrafts get even stronger inside the cloud. Although only about 1/10th the magnitude, I would expect a similar effect as the heat of fusion is added to the mix at the freezing level.