24 Traditional Chinese Seasonal Divisions
People often have many questions when they hear about the 24 Traditional Chinese Seasonal Divisions, also known as the 24 Solar Terms. “What are Solar Terms?” “Are they superstitious symbols?” “Why are there 24 Solar Terms, and not 12?” “Are they very important to the people?” “What is their purpose?” “Are they part of the Chinese lunar year?”
The 24 Traditional Seasonal Divisions are a traditional weather system for agriculture that has been used for thousands of years in China. A year is divided into 24 parts to form the 24 Solar Terms that ancient Chinese people believed ensured “good timing” and “geographical convenience” for a good harvest. They also used their astronomical observations, particularly of meteorological phenomenon, to plan long-term farming practices. The ancient Chinese people were probably unable to tell the exact dates and time, but they knew the 24 Solar Terms well because those were vital to farming.
Today, even though science and technology have been significantly developed, the Solar Terms are still popularly used, both in China and among Chinese people living abroad. These terms are often mentioned in weather forecast or on calendars. People will remind each other when a new term comes; they have become an integral part of life for Chinese people.
Farmers plan their harvests according to the Solar Terms, while urban people change seasonal clothing and diets also in accordance with the Solar Terms. They may say, “It’s Lichun (Beginning of Spring) now,” and then prepare to put on light clothes for spring. Also, if it is “Yushui (Rain Water),” which means rainy season will come soon, people know that they need to take raincoats or umbrellas when they go out. If it is “Xiaoxue (Slight Snow),” people are aware that there will be snowy weather soon.
People also rely on the 24 Solar Terms to guide their diets. According to traditional Chinese medicinal theories, people should eat different foods in different seasons. For instance, people should eat more vegetables and fruits in spring, more light and heat-reduction food in summer, more vitamin-rich food in autumn, and more nutritious food in winter.
How Were the 24 Solar Terms Decided?
The earth moves around the sun in a circle over the course of one year; according to the ancient Chinese, the sun also moves during the year across the celestial sphere, along a fictitious path measured in 360 degrees longitude, known as the ecliptic. The 24 Solar Terms are decided by the position of the earth on its moving track or the position of the sun on the ecliptic, with the Vernal Equinox marking 0ºon this imaginary line, and each two of the 24 points are spaced by 15º. That is to say, ancient Chinese set those Solar Terms according to the length of days and nights, and the shadow of the sun on the ground at noon.
Xiazhi (Summer Solstice), Dongzhi (Winter Solstice), Chunfen (Vernal Equinox) and Qiufen (Autumnal Equinox) were the first four Solar Terms which appeared in ancient China; then they were followed by Lichun, Yushui, Lixia (Beginning of Summer), Xiaoshu (Slight Heat), Liqiu (Beginning of Autumn), Chushu (Limit of Heat), Bailu (White Dew) and Shuangjiang (Frost’s Descent) in the Qin Dynasty (221-206 BC); later, more were added by the West and East Han dynasties (206 BC-220 AD), making the complete 24 Solar Terms, to satisfy the needs of farming.
The Yellow River area in ancient central China was the country’s political and economic center, so the Solar Terms were based on the weather and farming seasons in that area. Most of the terms fall on the 6th or 21st days every month in the first half of the year and on the 8th or 23rd days every month in the second half of the year, with one or two days in difference. The traditional Chinese calendar, however, starts the solar year with the “Lichun (Beginning of Spring).”
