The physics of charging a hailstone freely falling in a thunderstorm cloud

Interaction between a charged watered coarse hailstone and likely charged droplets in a uniform electrostatic field is analyzed using the electrostatic methods of images. It is shown that, under certain external conditions characteristic of a thunderstorm cloud, the droplets are attracted to the likely charged hailstone. Owing to collisions with the droplets, the hailstone freely falling in a thunderstorm cloud can gather a charge large enough to initiate a corona discharge in its vicinity.