Ice prisms: falls of unbranched ice crystals in the form of needles, columns or plates, can be very small and suspended in the air. These crystals may fall from clouds or from a cloudless sky. Are sometimes associated with halo phenomena.
Snow grains: precipitation of very small white and opaque grains of ice. These grains can be fairly flat or elongated; their diameter is generally less than 1 mm.
Snow pellets: (formerly called 'soft hail'): precipitation of white and opaque compressible pellets that often bounce when hitting a hard surface. Can be spherical, but mostly are conical in shape; their diameter is usually 2-5 mm, but can be larger.
Ice pellets: (formerly called 'grains of ice' or 'small hail'): precipitation of hard transparent or translucent pellets of ice, spherical or irregular often showing a layered structure, rarely conical; their diameter is less than 5 mm.
Large hail: precipitation pieces of ice (hailstones) with a diameter of 5 mm, or more, they are accretions of clear and opaque ice. They usually fall as separate pieces, but may be agglomerated into irregular lumps.