supercooled cloud Cloud containing pure water droplets at temperatures considerably below the nominal freezing temperature of 0°C. With very pure water (i.e. free from pollutants), supercooling of liquid drops can occur down to around−40°C; altocumulus cloud, for example, is usually composed of water droplets at temperatures well below 0°C. See also CLOUD SEEDING.

supercooled cloud Cloud containing pure water droplets at temperatures considerably below the nominal freezing temperature. With very pure water (i.e. free from pollutants), supercooling of liquid drops can occur down to around −40°C; altocumulus cloud, for example, is usually composed of water droplets at temperatures well below 0°C. See also cloud seeding.