What are the forming factors of rainstorm?

Heavy rain refers to rain with high precipitation intensity. According to the regulations of China's meteorological department, a rainstorm is called when the rainfall reaches 1 6 mm within1hour or exceeds 50 mm within 24 hours. According to the intensity, it can be divided into general rainstorm, heavy rainstorm and extremely heavy rainstorm, that is, the rainstorm with rainfall less than 70 mm within 12 hours or less than 100 mm within 24 hours is called "general rainstorm"; /kloc-A rainstorm with a rainfall of more than 70mm and less than140mm in 0/2 hour, or a rainfall of more than100mm and less than 200mm in 24 hours is called a "heavy rainstorm"; /kloc-A rainstorm with rainfall exceeding 140mm in 0/2 hours or 200mm in 24 hours is called a "heavy rainstorm".

The formation process of rainstorm is very complicated. It needs rich water vapor in the atmosphere, especially the saturated layer in the lower troposphere is thick; There must be a strong updraft, so that water vapor can form clouds and cause rainfall; There should be long-lasting heavy precipitation, that is, the weather system moves slowly or repeatedly; There should be favorable terrain uplift, which leads to the concentration of rain belts in a certain place and contributes to local heavy rain. As far as weather system is concerned, rainstorm is often the product of the interaction and restriction of various weather systems, and the activities of cyclones, fronts, troughs, vortices, shear lines, typhoons and other systems can all contribute to rainstorm.

Rainstorms are very harmful and often cause unexpected floods.