By international convention, precipitation in the form of rain is classified according to the quantity that falls.
Precipitation that results in over 0.3 in accumulation per hour.
Precipitation that results in 0.1 to 0.3 in accumulation per hour.
Precipitation of water drops over 0.02 in in diameter; it results in accumulations of 0.1 in per hour.
Uniform continuous precipitation of slow-falling water droplets between 0.008 and 0.02 in in diameter.