What encyclopedia is the 24 solar terms called?

The twenty-four solar terms are also called the third class.

The origin of the twenty-four solar terms

The earth goes around the sun once, which is called one year old. The climate of one year old is uneven, because the distance between the earth and the sun is different in different areas of the earth.

As far as the northern hemisphere is concerned, when the earth reaches the Tropic of Cancer at 23 degrees 27 minutes 45 seconds south latitude, there will be oblique sunlight, so the climate is cold, so it is called "winter solstice". When it reaches the Tropic of Cancer at 23 degrees 27 minutes 45 seconds north latitude, there will be direct sunlight, so the climate is hot, so it is called "summer solstice", while the northern and southern hemispheres are just the opposite.

From winter to summer, when the earth runs between winter solstice and summer solstice, it is moderately hot and cold, which is called "vernal equinox". From summer solstice to winter, when the earth runs between summer solstice and winter solstice, the climate is equal to the vernal equinox, which is called "autumn equinox". The vernal equinox, autumnal equinox, summer solstice and winter solstice are the origins of the four seasons, that is, there are more than four times a year.

Starting from the vernal equinox, if Sunday is divided into 360 degrees, then the vernal equinox is 0 degrees, the summer solstice is 90 degrees, the autumn equinox is 180 degrees, and the winter solstice is 270 degrees. Then if the distance is 90 degrees, it is 15 degrees, and there are 24 fifteen degrees in a week, which is called twenty-four solar terms.

Among them, the first solar term of each month is "solar term", that is, beginning of spring, Jingzhe, Qingming, Changxia, Mangzhong, Xiaoshu, beginning of autumn, Bailu, Hanlu, beginning of winter, Heavy Snow, Xiaohan, etc. 12 solar terms; The second solar term of each month is "Zhongqi", that is, there are 12 solar terms such as rain, vernal equinox, Grain Rain, Xiaoman, summer solstice, summer heat, summer heat, autumn equinox, first frost, light snow, winter solstice and great cold.

"Solar term" and "neutral qi" appear alternately, each lasting 15 days. Now people have called "solar terms" and "neutral gas" solar terms.