The first snow in Beijing on Xiaohan on January, 20, 2022. (PHOTO:VCG)

By BI Weizi

The "Twenty-four Solar Terms" is a system of knowledge and social practice developed by ancient Chinese people through observing the annual movement of the sun and perceiving the changes of seasons, climate and weather during the year. Originateding from the Yellow River basin in ancient times, the 24 Solar Terms hasve since been widely adopted by other places in China as well as its neighbouring countries.

In 2006, the 24 Solar Terms were selected as the first batch of national intangible cultural heritage representative items. In 2016, they were listed aon UNESCO’s the Representative List of Intangible Cultural Heritage of Humanity of UNESCO.

Xiaohan (lesser cold) is the 23rd solar term, which falls on January 5, 2023. It begins when the sun reaches the celestial longitude of 285° and ends when it reaches the longitude of 300°. During Xiaohan, while the direct sun point is still in the southern hemisphere, the heat in the northern hemisphere is still in a state of dissipation. The heat absorbed during the day is less than the heat released at night, so the temperature in the northern hemisphere is continuing to drop. After the winter solstice, cold air frequently moves south, and the temperature continues to drop to the lowest on Dahan (Great Cold).