Origin and purpose of 24 solar terms There are two spellings for the 24 solar terms, one is a traditional Chinese 二十四節氣, another spelling is the simplified Chinese二十四节气. The twenty-four solar terms have a history of over 2000 years. It was adopted in ancient times to serve as a supplementary calendar for guiding agricultural affairs. Owing to the extremely large territory of China, the formulation of the twenty-four solar terms mainly took account of the climatic conditions of the yellow river valley. Therefore, the twenty-four solar terms could be used only as a reference for farming of different regions. China 24 Solar Terms How 24 solar terms work? The twenty-four solar terms are evenly arranged into the 12 months of a year, with each term (a climatic period) lasting 15 days or half a month. The beginning of spring, the beginning of summer, the beginning of autumn and the beginning of winter usher in the four seasons. The spring equinox, the autumn equinox, the summer s...