The dates of the twenty-four solar terms are defined as follows:
The number of days that the sun passes from zero degree of the yellow meridian to every 15 degrees of the yellow meridian is known as "a solar term". Each year, the sun travels 360 degrees and experiences 24 solar terms, two per month.
Which, the first of the month for the "festival", namely: spring, hibernation, Qingming, summer, mango, small summer, autumn, white dew, cold dew, winter, snow and small cold and other 12 festivals; the second of the month for the "gas", namely: rain, spring equinox, grain, and so on, and so on. The second solar term of each month is "Zhongqi", i.e., 12 solar terms: rain, spring equinox, grain rain, small full, summer solstice, summer heat, summer vacation, fall equinox, frost, snow, winter solstice, and big cold.
"Festival" and "mid-qi" alternate, each lasting 15 days, and now people have "festival" and "mid-qi" collectively called "festival" and "mid-qi". Nowadays, people have collectively referred to "Node Qi" and "Middle Qi" as "Setsubun".
Twenty-four solar terms formula: Calculation of the date of spring Calculation formula: [Y * D + C] - L
Twenty-four winds, also known as the twenty-four flowers letter winds, because it is in response to the flowers of the wind, so it is called letter. As the saying goes, "Flowers and trees manage the seasons, and birdsong reports the agricultural time", the flowers, plants, trees, birds and animals in nature are all active according to certain seasonal seasons, and their activities are closely related to the climate change.
Therefore, their various activities have become the sign of the season, such as plant shade buds, leaves, flowers, fruits, leaf yellow and leaf fall, animal hibernation, recovery, the beginning of the song, breeding, migration, etc., are subject to the constraints of climate change, the people of these natural rhythms is called a phenomenon called climate.