Rainstorm (English name torrential rain; rainstorm; Storm) refers to rain with high precipitation intensity, which is often formed in cumulonimbus clouds. According to the meteorological regulations in China, rain with an hourly rainfall of more than 16mm, or a continuous rainfall of more than 30mm for 12 hours and a 24-hour rainfall of 50 mm or more is called "rainstorm".
According to its precipitation intensity, it is divided into three grades, that is, the 24-hour precipitation is 50-99.9 mm, which is called "rainstorm", the 100-249.9 mm is called "heavy rainstorm" and the 250 mm is called "extraordinary rainstorm". However, due to the different characteristics of precipitation and topography, the standards of rainstorm and flood in different places are also different.
In business practice, rainstorm can be divided into local rainstorm, regional rainstorm, large-scale rainstorm and extra-large rainstorm according to the scope of occurrence and influence.
The local rainstorm lasts only a few hours or dozens of hours, and generally affects tens to thousands of square kilometers, causing less harm. However, when the rainfall intensity is extremely high, it can also cause serious casualties and property losses.
Regional rainstorm generally lasts for 3 ~ 7 days, and the influence range can reach 100 ~ 200,000 square kilometers or more. The disaster situation is average, but sometimes it may cause serious regional rainstorm and flood disaster due to the extremely strong rainfall intensity.
Extra-large-scale rainstorm lasts the longest, and it is generally a combination of continuous rainstorms in many areas. The rainfall can last intermittently for about 1 ~ 3 months, and the rain belt can be maintained for a long time. Torrential rain is a kind of disastrous weather, which often causes floods and serious soil erosion, leading to major economic losses such as engineering accidents, dike breaches and crop flooding. Especially for some low-lying and closed terrain areas, rainwater can not be quickly vented, resulting in farmland water accumulation and soil moisture over-saturation, which will cause more disasters.
(Editor: Wang Yongqing)
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