What are Solar Terms and how does one use them?
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24 Solar Terms
Solar Terms is a calendar of twenty-four periods and climate to govern agricultural arrangements in ancient China and functions even now. Each solar term has about 15 days and it is decided by the position of the sun in the sky.
How Does it Work?
These twenty-four solar terms each suggest the position of the sun every time it travels15 degrees on the ecliptic longitude. A cycle is that earth revolves around the sun for one time. It begins from the Beginning of Spring (Li Chun) and ends at Greater Cold (Da Han). In each month there are often two solar terms; the first one is generally named 'Jie Qi' and the other one 'Zhong Qi'. Their dates are mirrored by the Gregorian calendar, so we find that during the first half of a year 'Jie Qi' is around the 6th day of a solar month, 'Zhong Qi' around the 21st; in the second half of a year, 'Jie Qi' is around the 8th and 'Zhong Qi' around the 23rd.
24 Solar Terms in 2020
Solar Terms Date Meaning
Lesser Cold (Xiao Han) Jan. 6th It is rather cold
Greater Cold (Da Han) Jan. 20th The coldest moment of a year
The Beginning of Spring (Li Chun) Feb. 4th Spring begins
Rain Water (Yu Shui) Feb. 19th It begins to rain
The Waking of Insects (Jing Zhe) Mar. 5th Hibernating animals come to sense
The Spring Equinox (Chun Fen) Mar. 20th Day and night are equally long
Pure Brightness (Qing Ming) Apr. 4th It is warm and bright
Grain Rain (Gu Yu) Apr. 19th Rainfall is helpful to grain
The Beginning of Summer (Li Xia) May 5th Summer begins
Lesser Fullness of Grain (Xiao Man) May 20th Kernels plump
Grain in Beard (Mang Zhong) Jun. 5th Wheat grows ripe
The Summer Solstice (Xia Zhi) Jun. 21st It has the longest daytime and the shortest night of the year
Lesser Heat (Xiao Shu) Jul. 6th Torridity comes
Greater Heat (Da Shu) Jul. 22nd The hottest moment of a year
The Beginning of Autumn (Li Qiu) Aug. 7th Autumn begins
The End of Heat (Chu Shu) Aug. 22nd Heat hides
White Dew (Bai Lu) Sep. 7th Dew curdles
The Autumn Equinox (Qiu Fen) Sep. 22nd The mid of autumn
Cold Dew (Han Lu) Oct. 8th Dew is very cold
Frost's Descent (Shuang Jiang) Oct. 23rd Frost descends
The Beginning of Winter (Li Dong) Nov. 7th Winter begins
Lesser Snow (Xiao Xue) Nov. 22nd it begins to snow
Greater Snow (Da Xue) Dec. 7th It snows heavily
The Winter Solstice (Dong Zhi) Dec. 21st The shortest daytime and the longest night of a year
Meanings of 24 Solar Terms
These solar terms have meaningful titles. Some of them reflect the change of seasons such as the Beginning of Spring, the Beginning of Summer, the Beginning of Autumn, and the Beginning of Winter; some embody the phenomena of climate like the Waking of Insects (Jing Zhe), Pure Brightness (Qing Ming), Lesser Fullness of Grain (Xiao Man) and Grain in Beard (Mang Zhong); and some indicate the change of climate like Rain Water (Yu Shui), Grain Rain (Gu Yu), Lesser Heat (Xiao Shu), Greater Heat (Da Shu), and so on.
History and Origin
During the Shang Dynasty (17th century BC - 1046 BC), ancient people have decided 4 solar terms: The Spring Equinox (Chun Fen), The Summer Solstice (Xia Zhi), The Autumn Equinox (Qiu Fen), The Winter Solstice (Dong Zhi) by observing the shadow at noon. When the shadow is shortest in a year, it is Summer Solstice, the longest is Winter Solstice and the moderate is Spring Equinox or Autumn Equinox. In Zhou Dynasty (11th century BC - 221BC), eight solar terms were used. In 104 BC, the astronomical positions of 24 solar terms were decided.