How are China and the twenty-four solar terms divided?

The ancients fully considered the changes of various factors and natural phenomena in the division of solar terms. Beginning of spring, Changxia, beginning of autumn, beginning of winter, vernal equinox, autumnal equinox, summer solstice and winter solstice are used to reflect the seasons. Among them, the vernal equinox, autumnal equinox, summer solstice and winter solstice are divided from an astronomical point of view, reflecting the turning point of solar height change.

Beginning of spring, Changchun, beginning of autumn and beginning of winter reflect the beginning of the four seasons. The five solar terms of slight summer heat, great summer heat, summer heat, slight cold and great cold reflect the change of temperature. The four solar terms of rain, Grain Rain, light snow and heavy snow reflect the phenomenon of precipitation, indicating the time and intensity of rainfall and snowfall.

The three solar terms, White Dew, Cold Dew and First Frost, on the surface reflect the phenomenon of water vapor condensation, but in essence, they reflect the process and degree of gradual temperature drop. Xiaoman and Miscanthus reflect the maturity and harvest of related crops. Awakening and clarity reflect natural phenology and indicate the return of spring.

As early as the Spring and Autumn Period and the Warring States Period, China began to measure the length of the midday sun shadow with earth gauge. Four solar terms, namely, winter solstice, summer solstice, vernal equinox and autumn equinox, are determined. By the Qin and Han Dynasties, China had a complete concept of twenty-four solar terms. These are the crystallization of the wisdom of ancient Chinese people, which laid a good foundation for the later agricultural development and left valuable wealth for future generations.