Precipitation in the form of slowly falling, singular or unbranched ice needles, columns, or plates. They make up cirriform clouds, frost, and ice fog. Also, they produce optical phenomena such as halos, coronas, and sun pillars. May be called "diamond dust." It is reported as "IC" in an observation and on the METAR.
ICE CRYSTALS
Meaning of ICE CRYSTALS in English
Weather and meteorology English vocabulary. Английский словарь погоды и метеорологии . 2012