Hail typically forms in cumulonimbus clouds, which are large and dense thunderstorm clouds. These clouds have strong updrafts that carry water droplets up into extremely cold upper levels of the atmosphere. In these cold regions, the water droplets freeze into ice pellets, which can grow in size as they are carried up and down by the turbulent winds within the cloud. Once the hailstones become too heavy for the updrafts to support, they fall to the ground as hail. Hailstones can vary in size, from small pebbles to large golf balls or even larger.
