The Temperature of Hailstones

Abstract

A rigorous study was made of the temperature profile in spherical and homogeneous hailstones falling through clear air. It is found that a stone 1 cm in radius is liable to be a dozen degrees Celsuis colder than the ambient air. For larger stones, the temperature difference becomes greater. The cooling effect of hail on the air is relatively small, if hall-size distributions of the sort commonly observed at the ground are considered. When a stone (1.1 cm in radius) falls through cloud, its heat capacity delays the commencement of wet growth by as much as 2 km. On the other hand, when hail grows in surroundings of high liquid water content, the heat capacity term of even the largest hail in the heat balance equation is quite unimportant. Such growth normally leads to mixtures of water and ice.