Drizzle - Occurrence

Occurrence

Drizzle tends to be the most frequent form of precipitation over large areas of the world's oceans, particularly in the colder regions of the subtropics. These regions are dominated by shallow marine stratocumulus and trade wind cumulus clouds, which exist entirely within the marine boundary layer. Despite the low rates of surface accumulation, it is becoming apparent that drizzle actually exerts a major influence over the cloud structure, coverage, and radiative properties in these regions. This has motivated scientists to design more sophisticated, sensitive instruments such as high frequency radars that can detect drizzle. These studies have shown that the quantity of drizzle is strongly linked to cloud morphology and tends to be associated with updrafts within the marine boundary layer. Increased amounts of drizzle tend to be found in marine clouds that form in clean airmasses that have low concentrations of cloud droplets. This interconnection between clouds and drizzle can be explored using high resolution numerical modeling such as large eddy simulation.