Freezing drizzle
Freezing drizzle is drizzle that freezes on contact with the ground or an object at or near the surface. Its METAR code is FZDZ. Formation Although freezing drizzle and freezing rain are similar in that they both involve liquid precipitation above the surface in subfreezing temperatures and freeze on the surface, the mechanisms leading to their development are entirely different. Where freezing rain forms when frozen precipitation falls through a melting layer and turns liquid, freezing drizzle forms via the supercooled warm-rain process, in which cloud droplets coalesce until they become heavy enough to fall out of the cloud, but in subfreezing conditions. Despite this process taking place in a subfreezing environment, the liquid water will not freeze if the environmental temperature is above , via supercooling. If ice crystals are already present in this environment, the liquid droplets will freeze onto these crystals and be effectively removed before they can grow large enough to fall out of the cloud. As a result, freezing drizzle develops in shallow low-level stratus-type clouds where air saturation occurs entirely below the layer in which ice crystals can develop and grow. Effects When freezing drizzle accumulates on land, it creates an icy layer of