rain forms

By international convention, precipitation in the form of rain is classified according to the quantity that falls.

heavy rain

Precipitation that results in over 0.3 in accumulation per hour.

moderate rain

Precipitation that results in 0.1 to 0.3 in accumulation per hour.

light rain

Precipitation of water drops over 0.02 in in diameter; it results in accumulations of 0.1 in per hour.

drizzle

Uniform continuous precipitation of slow-falling water droplets between 0.008 and 0.02 in in diameter.