1, long summer is one of the 24 solar terms. Twenty-four solar terms are special festivals in the dry calendar, indicating the change of natural rhythm and establishing "December construction". At first, it was based on the changes of stars. The Big Dipper rotates circularly, and bucket handle rotates clockwise, so it is called one of the "years old" (Figure). Every rotation cycle starts from beginning of spring and ends with the Great Cold. When the stars change, the natural rhythms in certain areas of China are also changing gradually. During the period of Emperor Wu of the Western Han Dynasty, "Twenty-four solar terms" were incorporated into the taichu calendar Law as a supplement to the calendar to guide agriculture in the Yellow River basin. In the Yellow River basin, the day with the longest sun shadow and the shortest day is the winter solstice, and the winter solstice is the starting point of the "24 solar terms". The winter solstice and the next winter solstice are divided into 24 equal parts, the time between each solar term is equal, and the interval between each solar term is 60. The current "twenty-four solar terms" are divided according to the Yellow Sutra of the Sun (which has been used since 1645), that is, the annual movement track of the sun is divided into 24 equal parts, each 15 is 1 equal part, and each 1 equal part is a solar term. "Twenty-four solar terms" is an important part of the long history and culture of the Chinese nation and embodies the historical and cultural essence of Chinese civilization.
2. Twenty-four solar terms scientifically reveal the laws of astronomical and meteorological changes, which not only play a guiding role in agricultural production, but also affect ancient people's food, clothing, housing and transportation, and even cultural concepts. It skillfully combines astronomy, natural rhythm and folk custom, and derives a large number of related seasonal cultures, which has become an important part of China traditional culture. In order to express the characteristics of time series more accurately, the ancients divided solar terms into four groups according to climate 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. "Open" is beginning of spring and Changxia, "closed" is beginning of autumn and beginning of winter. Beginning of spring, Changxia, beginning of autumn and beginning of winter are collectively called "four calendars" and add up to * * * as "eight festivals". Folk call it "four seasons and eight festivals" or "eight festivals a year" In the long farming society, the 24 solar terms have played an important guiding role in farming activities and have rich cultural connotations.