What is the origin of Xiaoman solar terms?

This solar term means that the grain of summer grain begins to be full, but it is not mature, just small but not full. It means that the sun reaches 60 every year between May 20th and 22nd in the Gregorian calendar. At that time, the seeds of summer grain in the north were gradually full, early rice began to ear, and small grains began to appear on rice. The south entered the summer harvest season in summer sowing.

The arrival of Xiaoman solar term means that it has entered the rainy season of heavy precipitation, and the rain begins to increase, which often leads to continuous and large-scale heavy precipitation. Xiaoman, like rain, Grain Rain, light snow and heavy snow, are solar terms that directly reflect precipitation. It fully reflects the climatic characteristics of heavy rainfall: Is the river full? (South).