What is the meaning of Dahan solar term?

The Great Cold is the last solar term among the twenty-four solar terms. Every year on January 20-21 of the Gregorian calendar, when the sun reaches 300° of ecliptic longitude, it is the "Great Cold". "Shishi Tongkao·Tianshi" quoted from "Sanli Yizong" and explained: "The big cold is the middle, and the upper shape is better than the minor cold, so it is called the big... The cold air is the reverse extreme, so it is called the big cold."

It is extremely cold. This season falls between March and April, when cold waves move south frequently. It is the coldest time of the year and also the time with the least rain. Folk proverb goes: "Small cold and big cold are cold when there is no wind." Dahan means that the weather is extremely cold. It is a season when vitality is latent and everything is dormant.

Meteorological changes in the Great Cold solar term

During the Great Cold solar term, the atmospheric circulation is relatively stable, and the circulation adjustment period is about 20 days. When this kind of circulation adjusts, large-scale rain, snow, and windy cooling often occur.

When there is a long-wave ridge to the west of 80 degrees east longitude and a large coastal trough in East Asia, China will experience persistent low temperatures due to the control of northwesterly airflow and the continuous replenishment of cold air. In some areas of my country, the major cold is not as good as the minor cold, but in the coastal areas of southern my country, the lowest temperature throughout the year occurs during the major cold solar term.

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The above content refers to Baidu Encyclopedia - Dahan