The winter solstice is one of the "24 solar terms". During the period of Emperor Wu of the Han Dynasty, twenty-four solar terms were absorbed into the taichu calendar as a supplement to the calendar guiding farming, and the solar terms were divided by the method of "balancing qi" (that is, the average time method).

"Pingqi Method" uses photogrammetry to determine the shortest day in the Yellow River basin as the winter solstice, divides the date between the winter solstice and the next winter solstice into twelve equal parts, which is called "Zhongqi", and then divides the dates between adjacent "Zhongqi" into equal parts, which is called "solar terms"; On average, there is a "neutral gas" and a "solar term" every month, which are collectively called "24 solar terms".

Second, the winter solstice custom:

1, eat jiaozi and wonton in the north.

In northern China, there is a custom of eating jiaozi on the winter solstice. On this day every year, jiaozi is an indispensable holiday meal for the rich and the poor. According to legend, this custom is to remember the kindness of Zhang Zhongjing, a "medical sage", in "Quhan Jiaoer Decoction".

The significance of winter solstice wonton is mainly sacrifice, followed by eating. Some ancient people thought that eating wonton on the winter solstice was to break the yin and release the yang and support the growth of yang between heaven and earth.

2, eat dumplings in the south

Eating glutinous rice balls on the winter solstice is a traditional custom in China, especially in the south of the Yangtze River. There is a saying among the people that "eating glutinous rice balls is one year older". Tangyuan can be used to worship ancestors, to give gifts to relatives and friends, and to represent the meaning of reunion.

Climatic characteristics

The arrival of the winter solstice solar terms marks the beginning of the cold winter. On this day, although the northern hemisphere got the least solar radiation, it was about 50% less than the southern hemisphere. However, this is not the coldest time, the so-called "cold in March 9, April 9". This is because there is atmosphere and water on the surface of the earth, which can store heat, not "save or lose", but "accumulate heat"

Therefore, the weather is usually not very cold before the winter solstice. After the winter solstice, although the solar altitude angle gradually increased, it was a slow recovery process, and the heat lost every day was still greater than the heat received, showing a situation of "making ends meet".

On the "March 9, April 9", the accumulated heat is the least, the temperature is the lowest, and the weather is getting colder and colder. At this time, if there is the influence of cold air, the weather is even colder. After this "cold front", the weather will gradually get warmer.

Reference to the above content? Baidu encyclopedia-winter solstice