Precipitation of pellets of ice, often associated with thunderstorms.
Hailstones have diameters of 2–250 mm, 2–5 mm being most common.
They require a strong updraft, raising them to colder regions, to form.
Often this happens several times, the hailstone collecting a new layer of
ice each time it rises, until it is too heavy to support and falls to the
ground. Larger hailstones may have alternate layers of clear and white ice,
due to different rates of freezing.
|Hailstones on the ground. Image source:
PHENOMENA AND STRUCTURES