The 24 solar terms is a gross name of the system that consists of 12 major solar terms and 12 minor solar terms.
Ancient Chinese divided the circle of the annual motion of the sun into 24 equal segments; each segment was called a “jie qi” or solar term. Hence the 24 segments are collectively called the 24 Solar Terms. This system of time embodies the traditional knowledge and the social practices through which Chinese organize their perception of the regularity of seasons, of astronomical laws and of other local natural phenomena occurring in the course of the year. It is an indispensable component of the traditional Chinese calendars and its living applications, serving as a time-frame for agricultural activities and daily life. In international circle of meteorology, this cognitive system has been honored as the Fifth Great Invention of China.
The 24 Solar Terms originated in the Yellow River reaches of China. The criteria for its formulation were developed through the observation of changes of astronomical time sequence, air temperature, precipitation, as well as other natural phenomena in this region. It has been progressively applied as a time directory in the production and life of agricultural society and then shared by many ethnic groups.
Transmitted through generations, the element has profoundly influenced Chinese people’s way of thinking and code of conduct. Upon a specific solar term, people spontaneously arrange farming and daily routine as well as basic necessities of life. Thus this knowledge continuum of time is sustained through a variety of ritual practices and folk activities. Thereby the 24 Solar Terms is an important carrier of Chinese cultural identity.
The solar terms are: Beginning of Spring, Rain Water, Insects Awakening, Spring Equinox, Fresh Green, Grain Rain, Beginning of Summer, Lesser Fullness, Grain in Ear, Summer Solstice, Lesser Heat, Greater Heat, Beginning of Autumn, End of Heat, White Dew, Autumnal Equinox, Cold Dew, First Frost, Beginning of Winter, Light Snow, Heavy Snow, Winter Solstice, Lesser Cold, and Greater Cold.
The UN Educational, Scientific, and Cultural Organization (UNESCO) has adopted a decision that China's "The 24 Solar Terms" be inscribed on the Representative List of the Intangible Cultural Heritage of Humanity during the 11th session of the UNESCO Intergovernmental Committee for the Safeguarding of the Intangible Cultural Heritage in Ethiopia's capital Addis Ababa on November 30, 2016.