What is rainfall, and what instrument is used to measure rainfall?

what is rainfall? How is the rainfall measured

The depth of the water layer accumulated on the water surface by the rain falling from the sky to the ground without evaporation, infiltration and loss is called rainfall (in millimeters), which can directly indicate the amount of rainfall.

At present, the commonly used instruments for measuring rainfall include rainfall cylinder and measuring cup. The diameter of the rainfall tube is generally 2 cm, and it is equipped with a funnel and a bottle. The measuring cup has a diameter of 4 cm, and it is used together with the rainfall tube. When measuring, pour the rainwater in the rainfall cylinder into the measuring cup, and you can know the rainfall of the day according to the scale on the cup.

according to the regulations of China Meteorological Bureau, the rainfall within 24 hours is called daily rainfall, and the daily rainfall below 1mm is called light rain, 1.-24.9mm is moderate rain, 25.-49.9mm is heavy rain, 5.-99.9mm is heavy rain, 1.-25.mm is heavy rain, and over 25.mm is called torrential rain. Due to China's vast territory, a few areas have other regulations according to the specific conditions of Guangdong Province. For example, in rainy Guangdong, the daily rainfall of more than 8 mm is called rainstorm; In Yan 'an, Shaanxi Province, where there is little rain, it is called rainstorm when the daily rainfall reaches more than 3 mm.