Hail

Hail is a destructive form of precipitation that is 5 to 190 millimeters in diameter. The large downdrafts in mature thunderstorm clouds provide the mechanism for hail formation. Hailstones normally have concentric shells of ice alternating between those with a milky appearance and those that are clear. The milky white shells, containing bubbles and partially melted snowflakes, correspond to a period of rapid freezing, while the clear shells develop as the liquid water freezes much more slowly.