Question

What causes hail formation?

Answer 1

Hail is caused when raindrops are lifted up into the atmosphere during a thunderstorm and then supercooled by temperatures below freezing, turning them into ice balls.

So, to break it down, hail originally is rain, which we know is a liquid water precipitate. If conditions allow, rain drops can be lift back up into the clouds and surrounding atmosphere on updrafts, where the temperatures cool and freeze the raindrops into small chunks of ice, which fall as hail.