【How-to】What is a drizzle of rain

Rain: Precipitation in the form of liquid water drops that have diameters greater than 0.5 millimeter; if less than 0.5 millimeter, it is drizzle. … Drizzle is classified as light, falling at a rate from a trace to 0.01 inch per hour; moderate, 0.01 to 0.02 inch per hour; heavy, greater than 0.02 inch per hour.