The winter solstice is the 22nd solar term in the "24 solar terms", and the solar calendar reaches 270 degrees. Every year, the festival is 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 solar altitude angle 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 a turning point for the sun to return directly to the north. After this day, the direct point of the sun will go back. The direct point of the sun will move northward from the Tropic of Capricorn (23 26' s), and the daylight in the northern hemisphere (China is located in the northern hemisphere) will increase day by day.
In winter solstice, although the sun is low and the days are short, the temperature in winter solstice is not the lowest in meteorology. In fact, because there is still "accumulated heat" on the surface, it is usually not very cold before the winter solstice, and the real cold is after the winter solstice.
Because of the great difference in climate in different parts of China, this winter climate is obviously late for most parts of China. The winter solstice marks the beginning of the cold season, and people begin to count to nine to calculate the cold weather (folk proverb: "The summer solstice is three Geng, and the winter solstice is nine").
Calendar phenomenon
The date of winter solstice in 2020 is 65438+February 2 1, and the date of winter solstice in 2026 is also 65438+February 2 1. The date of winter solstice for two consecutive years is 65438+February 2 1, which is a very rare calendar phenomenon.
According to statistics, this strange calendar phenomenon last appeared in 1896 and 1897, that is, 124 years ago. The main reason for this calendar phenomenon is that the length of the current solar calendar is inconsistent with the length of the tropic year.
According to statistics, from 2056, for three consecutive years (2056-2058), the date of winter solstice is 65438+February 2 1. Stranger still, since 2088, the date of winter solstice has been 12 (2088- 1999), and now it is 12,21. This calendar phenomenon has never been experienced by anyone in the world today.