Drizzle
Light liquid precipitation
Drizzle is a light, sporadic precipitation which consists of liquid water drops that are smaller than those of normal rain – generally smaller than 0.5 mm (0.02 in) in diameter. Drizzle is normally produced by low stratiform clouds and stratocumulus clouds. Precipitation rates from drizzle are on the order of a millimetre (0.04 in) per day or less at the ground.
From Wikipedia, under CC BY-SA. More on occurri.