Classification of solar terms in the twenty-four solar terms of the lunar calendar

24 solar terms can be divided into the following three categories according to different phenomena:

The first category reflects the seasons. The vernal equinox (vernal equinox, autumnal equinox), vernal equinox (summer solstice, winter solstice) and vernal equinox (beginning of spring, Changchun, beginning of autumn and beginning of winter) are used to represent seasons, and a year is divided into four seasons. The bisector and solstice are the turning points of the solar height change. Because it is divided from an astronomical point of view, it is applicable to all regions of China. Standing four times is not necessarily the case. Although it also reflects the beginning of the season from the astronomical point of view, due to China's vast territory, the monsoon and continental climate are extremely remarkable, and the climate varies greatly from place to place, the start date and duration of the four seasons are not the same, some areas have distinct seasons, some areas are not obvious, and even the whole season does not appear. For example, in the alpine region north of Aihui, there is no summer on the Qinghai-Tibet Plateau. There is a saying on the Qinghai-Tibet Plateau: "There is still cotton in June and summer, and it is mostly cold all year round." There is no winter in southern Fuzhou, South China, and it is summer in some areas almost all year round. It's really "when winter goes and spring comes, the grass will not wither", "It's always summer, and when it rains, it becomes autumn". Yunnan, Guizhou and other plateaus are another scene. Winter is short and there is no summer. Kunming is known as "four seasons like spring". Therefore, although it is divided from astronomy, it has a strong regional nature and cannot adapt to the whole country.

The second category reflects climate characteristics. There are five solar terms that directly reflect the summer heat: slight summer heat, great summer heat, summer heat, slight cold and severe cold, which are used to indicate the degree of cold and summer heat in different periods of the year and the imminent passing of the summer heat. There are four solar terms that directly reflect the precipitation phenomenon: rain, Grain Rain, light snow and heavy snow, indicating the time and intensity of rainfall and snowfall. In addition, although the three solar terms, White Dew, Cold Dew and First Frost, are the phenomena of water vapor condensation and condensation, they also reflect the process of gradual temperature drop and the degree of cooling in each solar term. First, the temperature began to drop, and more water vapor condensed; After that, the temperature dropped even more, not only exposed to the sun, but also cooled down, but it was not frozen; Finally, the temperature drops below zero degrees Celsius, and the water vapor condenses into frost. From the perspective of agricultural production, these three solar terms are concrete and vivid, with their heat meaning greater than their water meaning.

The third category reflects phenological phenomena. Xiaoman and awn species reflect the maturity and harvest of related crops; Frightening and Qingming reflect natural phenology, especially stinging. It uses the first thunder in the sky and the revival of underground stinging insects to inform everything in the world that spring is coming back to the earth.