Heat transfer from hailstones

By measuring the rate of melting of spheres and oblate spheroids of ice in an airstream, the dependence of the rate of heat transfer on shape has been determined. Applying the results to hailstones, it has been found that, in terms of the maximum dimensions of the stones, melting is more pronounced as the ratio of the minor to major axes decreases. Melting also causes the stones to become more oblate. The critical liquid‐water concentrations of spheroidal hailstones have been deduced from the experimental data and, for stones of the same maximum dimension, are dependent of the axis ratio. It is further shown that the updraught profiles required to grow spheroidal hailstones at the just‐wet condition are not much different from those required for spherical stones.