How did the rain solar term come from?

Rain is the second solar term in a year. "Between two dimensions, 9 1 degree and 16 degree" is divided into six solar terms on average, and each solar term accounts for 15 days. Therefore, fifteen days after winter, the solstice will be slightly cold, another fifteen days will be severe cold, and another fifteen days will be beginning of spring. Fifteen days after beginning of spring, it began to rain. This is how the date of the rain solar term is calculated.

Wu Cheng's book "Twenty-four Solar Terms" in the Yuan Dynasty said: "The first month is aquatic in the sky, and spring is wood. However, people who grow trees must have water, so it rained successfully in beginning of spring. If the east wind melts, it will disperse into rain. " Rain means that the spring breeze gradually blows all over the earth, the ice and snow melt, and even the air in the north begins to get wet, showing a thriving scene everywhere.

Meteorological changes of rainwater

From the meteorological point of view, the highest temperature in most parts of China can generally rise above 0℃ after the rain. Although it has entered the spring rain solar term, there is no breath of spring in most parts of northern China.

The average temperature in many areas of South China is above 10℃. At this time, rape, winter wheat, etc. Generally, it will turn green, which requires higher moisture. As the saying goes, "Spring rain is as expensive as oil", and suitable precipitation is very important for the growth of crops. At this time, the precipitation in North China, Northwest China and Huanghuai areas is generally less. If there is little rain in early spring, timely irrigation after rain is beneficial to crop growth.

Beijing Daily-How did the rainy solar terms come from?

Above content reference: Baidu Encyclopedia-Rain