Beginning of winter said that since then, winter has traditionally started with the 24 solar terms "beginning of winter". "beginning of winter" means wind and rain, humidity, light, temperature, etc. It is at a turning point, and the climate is gradually changing from autumn to winter. In winter, the direct point of the sun moves south to the tropic of Capricorn, and then turns back to the north.
In beginning of winter season, the sun has reached the longitude of 225 degrees, and the earth is located at declination-1619'. The height of the sun in the northern hemisphere becomes smaller, the daylight time is shortened, and the amount of solar radiation obtained by the northern hemisphere becomes less and less. However, the heat stored on the surface in the second half of this year still has some energy, so it is not very cold.
During the winter of Meng, when there is no wind on a clear day, there is often a sunny, warm and comfortable "Xiaoyangchun" weather, and there is a saying of "Xiaoyangchun in October" among the people.
In some parts of the south, it is generally not very cold in early winter, but with the passage of time, cold air frequently goes south and the temperature gradually drops. In the northern region, it is very cold from winter to spring, and the climate change of several solar terms in winter is not obvious. Snow is the main feature of northern winter.
Extended data:
In winter, the sun's light and heat energy will enter the least season of the year. Because there is not enough light and heat energy in the northern hemisphere, the air in the high latitudes will be cooled and sunk in large quantities to accumulate, and finally a cold wave will pour south.
After beginning of winter, a relatively stable winter circulation has basically formed in East Asia. The subtropical high has retreated to the south of 20 degrees north latitude in the Pacific Ocean, and the westerly belt has been pressed to the south of 35 degrees north latitude. The westerly belt will be divided into a north branch westerly wind and a south branch westerly wind on the Pamirs.
The westerly winds of the northern branch send the water vapor from the Mediterranean Sea and the North Sea to Tianshan Mountain to form snowfall, and the air after snowfall cools and accumulates in depth, forming cold air southward at the trough on the east side of the Qinghai-Tibet Plateau.
However, the south branch westerly wind forms a south branch trough on the south side of the Qinghai-Tibet Plateau and turns into the Bay of Bengal, transporting the water vapor from the Bay of Bengal to the central and eastern regions of China. When the cold air in the north branch trough meets the warm and humid air in the south branch trough, it will form low-temperature rain and snow weather.