How does a hail stone form?

Hailstones form within strong thunderstorms with intense updrafts. Water droplets are carried upward into extremely cold areas of the atmosphere, where they freeze into ice. As these ice particles cycle through the storm, they collide with supercooled water droplets that freeze upon contact, causing the hailstones to grow larger. Eventually, when they become too heavy for the updrafts to support, they fall to the ground as hail.