Precipitation refers to the depth at which liquid and solid (after melting) precipitation falls from the sky to the ground and accumulates on the horizontal plane without evaporation, infiltration and loss. His unit is millimeters. Meteorology uses precipitation to distinguish the intensity of precipitation. Can be divided into: light rain, moderate rain, heavy rain, heavy rain, heavy rain and so on.

Light rain: raindrops are clearly visible without floating; The ground does not splash; The water in the depression is very slow; The rain on the house is weak, and there is only dripping water on the eaves; 12 hour precipitation is less than 5mm or 24 hour precipitation is less than10mm.

Moderate rain: the rain falls like a line, and the raindrops are not easy to distinguish; Fall heavily and splash; Water accumulated in depression is faster; There is rustling rain on the roof; 12 hour precipitation 5 ~10 ~ 25mm or 24 hour precipitation10 ~ 25mm.

Heavy rain: the rain falls like a downpour, blurred into pieces; The water in the depression is extremely fast; There is rain on the roof; 12 hour precipitation15 ~ 30mm or 24-hour precipitation of 25 ~ 50mm.

Rainstorm: Any rainfall process with precipitation exceeding 50 mm within 24 hours is collectively referred to as rainstorm. According to the intensity of rainstorm, it can be divided into three types: rainstorm, heavy rainstorm and extremely heavy rainstorm. Rainstorm: a rainfall process in which the precipitation is 30 ~ 70 mm in 12 hours or 50 ~ 100 mm in 24 hours. Rainstorm: a rainfall process in which the precipitation is 70 ~140mm within 12 hours or100 ~ 250mm within 24 hours. Extraordinary rainstorm: the rainfall process in which the precipitation is greater than140mm in 2 hours or 250mm in 24 hours.

(I hope it helps you)