While the freezing point for water is 32 degrees Fahrenheit or 0 degrees Celsius, different types of snow can occur under certain conditions.Snow flurries are light snowfalls that fall but usually melt when hitting a surface and don’t accumulate unlike snow. Snow is clusters of thin ice flakes solidly frozen ice and occurs below the freezing point. Sleet is rain or drizzle that freezes into ice as it falls, and is best described between snow and frozen rain. Graupel is like tiny frozen droplets or frozen rain that does not melt when hitting a surface and do accumulate. Hail is completely frozen, larger than sleet and resembles stones. They form in thunderstorms when graupel (ice crystals in the atmosphere) cannot fall due to the upward flow of air in a storm. Supercooled water hits the graupel and forms to it until the weight of the forming hail stone causes it to fall.
answered Jul 12 '12 at 12:35