Where do the 24 solar terms apply?

Twenty-four solar terms are applicable to Huanghuai area and the middle and lower reaches of the Yellow River, such as Henan, Anhui, Jiangsu, Shanxi, Inner Mongolia, Shandong and other provinces.

The formulation of the 24 solar terms is based on the time series changes of astronomical phenomena, temperature, precipitation and phenology in the middle and lower reaches of the Yellow River. For other parts of China, the situation described by the same solar term may be quite different.

Twenty-four solar terms started from the four solar terms of mid-spring, mid-summer, mid-autumn and mid-winter in Shang Dynasty, passed through eight solar terms in Zhou Dynasty and reached the twenty-four solar terms in Western Han Dynasty. Subsequent dynasties have corresponding details to supplement and improve. However, judging from the time node of its emergence and development, people's activity center at that time was in Huanghuai area. Generally speaking, the 24 solar terms are summed up by combining the characteristics of the four seasons in this area with farming.

"Twenty-four solar terms" reflect the influence of the sun on the earth and belong to the solar calendar category. It is a knowledge system formed by observing the movement of the sun in a year and understanding the changing laws of the four seasons, climate and phenology in a year.

The current "twenty-four solar terms" are divided by "constant gas method", that is, each solar term corresponds to a certain position that the earth reaches every time it runs 15 on the ecliptic; The method of "fixing qi" divides the sun's annual movement track into 24 equal parts, each equal part is 15, and each equal part is a solar term, which starts from beginning of spring and ends with severe cold.