The division of the solar terms has fully considered the variation of natural phenomena, such as seasons, climates and phenology.
The solar terms known as Start of Spring, Start of Summer, Start of Autumn, and Start of Winter are used to reflect the change of seasons, dividing the year into four seasons of exactly three months. While this fits an ideal pattern of dates, it does not reflect observable reality in most of China.
The solar terms of Vernal Equinox, Autumnal Equinox, Summer Solstice and Winter Solstice are divided from an astronomical aspect, reflecting the turning point of the variation of the altitude of the sun.
Minor Heat, Major Heat, Limit of Heat, Minor Cold, and Major Cold reflect the changes of temperature in different periods.
Clear and Bright, Rain Water, Grain Rain, Minor Snow, and Major Snow, White Dew, Cold Dew, and Frost Descent reflect the phenomenon of precipitation, indicating the time and intensity of rainfall, snowfall, dew, and frost.
Small Full (Grain) and Grain in Ear reflect the maturity and harvest time of crops, while Awakening of Insects reflects observed insect activity.
Solar terms originated in China, then spread to Korea, Vietnam, and Japan, countries in the East Asian cultural sphere. Although each term was named based on the seasonal changes of climate in North China Plain, peoples living in the different climates still use it with no changes. This is exhibited by the fact that traditional Chinese, Hanja, and Kanji characters for most of the solar terms are identical.
On December 1, 2016, 24 Solar Terms were listed as UNESCO's Intangible Cultural Heritage.
