How does hail form?
Quick Answer
Hail forms inside thunderstorms when strong updrafts carry raindrops high into freezing air, where they collect layers of ice until they are too heavy and fall.
The Full Story
In tall cumulonimbus clouds, powerful rising air currents lift water droplets far above the freezing level. Droplets freeze onto small particles and collide with supercooled water, which freezes on contact and adds layers of ice. A hailstone may be carried up and down several times, building rings like an onion. When it grows too heavy for the updraft to support, it falls to the ground. The stronger the updraft, the bigger the hail can grow; the record US hailstone, found in Vivian, South Dakota, in 2010, measured 20 centimetres across.
Key Facts
YouTube Angle
Suggested video title for this topic:
"Balls of ice from the sky — how hailstones grow"