The shortest day and the longest night solar terms.

The winter solstice is the 22nd solar term in the "twenty-four solar terms", and the solar calendar reaches 270 degrees. Every year, festivals are held on 65438+February 2 1-23 in the Gregorian calendar. The solstice in winter is the extreme point of direct sunlight spreading to the south. From winter to the sun, the sun shines directly on the tropic of Capricorn, and the sun is most inclined to the northern hemisphere, and the elevation angle of the sun is the smallest. In all parts of the northern hemisphere, the days are the shortest and the nights are the longest.

The solstice in winter is also the turning point of direct sunlight returning to the north. After this day, it went back, and the direct sunlight began to move northward from the Tropic of Capricorn (23 26' s), and the sunlight in the northern hemisphere (China is located in the northern hemisphere) increased day by day.

The custom of winter solstice:

Many places in the south celebrate festivals in winter solstice. The southern coastal areas, such as western Guangdong, Chaoshan and parts of Zhejiang, continue the traditional custom of ancestor worship. Every household is dedicated to ancestor statues, memorial tablets, etc. Go to the hall at home, place an altar, set up incense burners, offerings, etc. In some places, while offering sacrifices to ancestors, they also offer sacrifices to gods, land gods and deities, so as to pray for a good weather and a prosperous family in the new year.

In many places in northern China, it is a custom to eat jiaozi from winter to Sunday every year. According to legend, Zhang Zhongjing, a medical sage, saw a frozen person when he retired in his later years, so he wrapped mutton, some cold-dispelling herbs and dough into the shape of ears, made a medicine called "Quhan Jiaoer Decoction" and gave it to the people. Later, every winter solstice, people imitated eating and formed a custom.