What does the solar term mean?

Twenty-four solar terms refer to the special festivals in the trunk and branch calendars that express seasons, phenology, climate change and the establishment of "December architecture", reflecting the influence of the sun on the earth and being listed in the representative list of human intangible cultural heritage. Twenty-four solar terms, a supplementary calendar established in the pre-Qin period and completely established in the Han Dynasty, 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. It divides the sun's annual trajectory into 24 equal parts, and each equal part is a solar term, starting from beginning of spring and ending with the great cold.

According to the law of the operation of heaven and earth, the ancients determined the starting point and ending point of the four-season cycle and divided the 24 solar terms. The trajectory of the sun in a year is divided into 24 equal parts, each of which is a "solar term", collectively called "twenty-four solar terms". Twenty-four solar terms represent twenty-four different positions of the earth in the orbit of revolution. Because it takes 365 days for the earth to go around the sun, there is a solar term every fifteen days, and each solar term represents different changes in climate, phenology and time. The spring rain shakes the spring and clears the valley, and the summer is full of mountains and summers. Autumn dew, autumn frost, little snow in winter and cold in winter. The solar term song, which is well known to China people, implies the order of the 24 solar terms.

All the year round begins with "four stands", and the so-called "stand" is the beginning. Beginning of spring, Changxia, beginning of autumn and beginning of winter represent the beginning and arrival of spring, summer, autumn and winter respectively. In order to express the characteristics of time series more accurately, the ancients divided the solar terms into four groups according to the weather and phenology: divided, arrived, opened and closed. "Fen" means vernal equinox and autumnal equinox, which was called "dichotomy" in ancient times; "Solstice" is the summer solstice and the winter solstice, which was called "the second solstice" in ancient times. "Qi" refers to beginning of spring and Changxia, "Closed" refers to beginning of autumn and beginning of winter, and beginning of spring, Changxia, beginning of autumn and beginning of winter are collectively called "Sili", which add up to * * * to "eight sections". Corresponding to the most important "eight festivals" in the solar terms. If you choose the key points in the eight sections, it is the "second solstice" of the summer solstice and the winter solstice. In winter solstice, the sun reaches the southernmost point, while in summer solstice, the sun reaches the northernmost point, which is what the ancients said: "The sun reaches the north, with long days and short shadows, so it is called summer solstice." Do your best.