How did the twenty-four solar terms come about?

24 solar terms is: beginning of spring, rainy, startled, vernal equinox, Qingming, Grain Rain, Changxia, Xiaoman, Mangzhong, Summer Solstice, Slight Summer, beginning of autumn, Early Summer, White Dew, Autumn Equinox, Cold Dew, Early Frost, beginning of winter, Light Snow, Heavy Snow, Winter Solstice, Slight Cold and Severe Cold.

Each solar term guides a certain season of farmers' agricultural production, is the crystallization of long-term experience and wisdom of hardworking people, and also brings timely agricultural reminders and climate to agriculture.

First of all, beginning of spring:

Around February 6th, symbolizing the beginning of spring, the temperature rises and spring returns to the earth. Rain: on February 2 1 day, the snowfall stopped and it began to rain, and the rainfall gradually increased. In production, it mainly guides farmers to do well in fertilizer and water management in the field, weeding in spring sowing crops, collecting farmyard manure, and making production work plans in Da Chun.

Second, shocked:

Around March 6th, when thunder started, hibernating animals that were dormant in the ground began to awaken and unearthed, and trees took root and sprouted, which was the best time for fruit grafting.

Third, the vernal equinox:

March 2 1 or so, the sun shines directly on the equator, and it is a warm spring in the middle of the night. In production, it is mainly the management of fertilizer and water in the middle and late spring crops, ploughing in winter, preparing enough agricultural materials such as seeds, fertilizers and agricultural films, and entering the spring ploughing work.

Fourth, Grain Rain:

Around April 20th. The rainfall is obviously increased, which is suitable for grain growth. In production, farmers are guided to raise rice seedlings, sow corn early and prepare for ploughing in spring. At the same time, pay attention to observe the weather and climate. There is a saying in "Agricultural Proverbs" that "the drought is less than May 13th". If it doesn't rain or seldom rains in Grain Rain, it is a sign of drought, so be prepared.

Extended data:

I. Division of solar terms

The twenty-four solar terms are divided according to the position of the earth on the ecliptic (that is, the earth's orbit around the sun). Depending on the sun starting from the vernal equinox (longitude zero, at this moment the sun shines vertically on the equator), every advance of 15 degrees is a solar term; After a week's operation, I returned to the vernal equinox, which is a tropical year with 360 degrees, so it is divided into 24 solar terms.

The ancients divided the sun's annual trajectory into 24 equal parts, each equal part is a solar term, and each solar term has three cycles, and each cycle is five days.

The ancients called solar terms "qi", and 24 solar terms were 24 qi, which were divided into solar terms and middle qi: the first qi at the beginning of each month was called "solar terms"; The second "Qi" in the middle of the month is called "Zhong Qi". In this way, there are 12 solar terms and 12 neutral terms throughout the year, which together are exactly "24 solar terms".

Second, the law

The twenty-four solar terms are determined by the direction of the top of bucket handle in the ancient Big Dipper. It is also related to the change of the earth's position on the ecliptic (that is, the earth's orbit around the sun), and each solar term corresponds to the climate law formulated at a certain position every time the sun runs on the ecliptic 15.

The earth's orbit around the sun was named "ecliptic" by the ancients, also known as "solar ecliptic". The ecliptic is divided into 24 equal parts, separated by 15, forming 24 solar terms. The 24 solar terms are actually 24 solar terms, 2 per month.

Twenty-four solar terms take the earth's revolution around the sun as a cycle, which basically summarizes the different positions of the sun on the ecliptic at different times of the year, the exact time of cold coming and summer going, the laws of natural phenomena such as rainfall and snowfall, and the time of recording some phenological phenomena in nature.

Baidu encyclopedia-24 solar terms