Supercooled water
From Glossary of Meteorology
supercooled water
Liquid water at temperatures below the nominal freezing point of pure water (~0°C for atmospheric-relevant pressure). This usually refers to cloud droplets, which often remain liquid for a long time at temperatures below 0°C. 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.
Term updated 23 March 2018.