The 24 solar terms is a gross name of the system that consists of 12 major solar terms and 12 minor solar terms.They refer to 24 days and climates. It is one of the great intellectual properties of Chinese Han people through thousands years of experience. It is a type of calendar used to guide the farming work. For ancient China is a agriculture society, farming work needs to strictly depend on the movement of the sun, therefore, the 24 solar terms are added to periodicity of the sun. It has played a crucial role in ancient China agrarian societies.
The 24 Solar Terms were listed as UNESCO's Intangible Cultural Heritage On November 30, 2016.In the international meteorological field, the 24 solar terms is hailed as "the China's fifth top inventions.Though it was initially originated in China, then spread to Vietnam, Korea and Japan, countries in the East Asian cultural sphere.
Major solar terms
It is based on the earth in the ecliptic (that is, the earth's orbit around the sun) on the changes in the location of the formulation, each corresponding to the earth in the ecliptic of each movement of 15 degrees to reach a certain location. Twenty-four solar terms are divided into 12 major solar terms and 12 minor solar terms. Starting from 'vernal equinox', the 12 major solar terms are 'vernal equinox', 'corn rain', 'corn forms', 'summer solstice', 'great heat', 'end of heat', 'autumnal equinox', 'frost', 'light snow', 'winter solstice', 'severe cold' and 'spring showers'.
Minor solar terms
The minor solar term after 'vernal equinox' is 'bright and clear', and then in turn 'summer commences', 'corn on ear', 'moderate heat', 'autumn commences', 'white dew', 'cold dew', 'winter commences', 'heavy snow', 'moderate cold', 'spring commences' and 'insects waken'.
At 'vernal equinox' and 'autumnal equinox', the length of daylight and the night are equal. The period of daylight is the longest at ‘summer solstice' and the shortest at ‘winter solstice' in northern hemisphere. These were the earliest solar terms determined in ancient time. Then it came the four solar terms 'spring commences', 'summer commences', 'autumn commences' and 'winter commences'.
Chinese 24 solar terms
Other solar terms were named later according to the weather and agricultural activities prevalent at the respective times of the seasons. The ‘24 solar terms' reflects to some extent the climate over central China in ancient time. They represent the early wisdom of Chinese people.
Here is an overview of the 24 solar terms in Chinese agricultural calendar
Spring commences (1st solar term) :meaning spring begins，date on 4th\5th February.
Corn Rain (2nd solar term):meaning air will start getting humid and forming rain, date on 19th\20th February.
Insects waken (3rd solar term) :meaning hibernating insects awaken,date 5th\6th March.
The Vernal Equinox (4th solar term):sun shining on equater，day and night account up same hours on this day, date 20th\21th March.
Bright and clear (5th solar term):meaning clear and bright,date 4th\5th April.
Grain Rain (6th solar term):wheat rain ,date 20th\21th April.
Summer commences (7th solar term):most palnt have staring grow,date 5th\6th May.
Corn Forms (8th solar term):date 21th\22th May.
Corn on ear (9th solar term):meaning wheat mature,date 5th\6th June.
Summer Solstice (10th solar term):date 21th\22th June,today sunlight shines directly on the tropic of Cancer.
Moderate heat (11th solar term):date 7-8 July.
Great Heat (12th solar term):date 22th\23th July.
Autumn commences (13th solar term):meaning autumn begins date 7th\8th August.
End of Heat (14th solar term):heat withdraws,date 23th\24th August.
White Dew (15th solar term):date 7th\8th September.
Autumnal equinox (16th solar term):date 23th\24th September.
Cold Dew (17th solar term):date 8th\9th October.
Frost (18th solar term):date 22th\23th October.
Winter commences (19th solar term):meaning winter begins, date 7th\8th November.
Light Snow (20th solar term):date 22th\23th November.
Heavy snow (21th solar term):date 7th\8th December.
Winter Solstice (22th solar term):date 22th\23th December.
Moderate cold (23th solar term):date 5th\6th January.
Greater Cold (24th solar term):date 20th’\21th January.