From AMS Glossary
Liquid water at temperatures below the nominal freezing point of pure water [~0°C (32°F) for atmospheric-relevant pressure]. This usually refers to cloud droplets, which often remain liquid for a long time at temperatures below 0°C (32°F). The actual freezing temperature of a supercooled cloud droplet depends on its size and composition and may be as low as several tens of degrees below 0°C (32°F).
Term updated 23 March 2018.