What are the different types of precipitation and how do they form?

Precipitation is the amount of water that falls from the atmosphere in different forms. There are eight types of precipitation - ice crystals, rain (and freezing rain), snow, drizzle (and freezing drizzle), snow grains, ice pellets, snow pellets and hail. Ice crystals occur when the air is very cold, and water vapour directly freezes into crystals. These crystals are not formed in clouds. On the other hand, snow arises from ice crystals in clouds when they collide and adhere to each other. Doctor Bergeron describes another process in which water molecules adhere to ice crystals, but it is too complicated to explain here. Snowflakes turn into rain if they melt while falling. If the temperature is below freezing point, then it results in freezing rain. Ice pellets are formed when below freezing temperature raindrops refreeze. Drizzle is the precipitation caused by water droplets falling slowly to the ground that are less than 0.5 millimeters in diameter. If they fall through a below freezing layer, they form freezing drizzle, and if the layer is thicker, it becomes solid and turns into snow grains. Snow pellets and hailstones are both formed in updrafts. Snow pellets are smaller than hailstones; in updrafts, snow kernels go back and forth through the water until they are too heavy for the updrafts to sustain them. Sleet, a common term, refers to either snow melting or ice pellets. Therefore, it is not designated as an official precipitation since it has different definitions.