A fall of non-branched (snow crystals are branched) ice crystals in the form of needles, columns, or plates.
unbranched ice crystals that fall as needles or plates. They only occur at cold temperatures (lower than -20 C) and can fall from a cloudless sky.
A barely visible crystalline form of ice that has the shape of needles, columns or plates. Ice crystals are so small that they seem to be suspended in air. Ice crystals occur at very low temperatures in a stable atmosphere.