Scientists have long been classified type of snow as crystals and snowpack. Now crystal can be divide into three different categories according to its atmospheric conditions. Hoarfrost is the deposition of ice crystals on a surface when the temperature of the surface is lower than the frost point of the surrounding air. Graupel is a type of snow crystals that forms as a snow crystals fall through supercooled cloud droplets. Polycrystals are snow crystals composed of many individual,ice crystals.