Why is winter on solstice not the coldest?

This is because the "winter solstice" in the northern hemisphere has the shortest day and the longest night, and the heat absorbed by the ground is less than the heat lost. However, due to the large amount of heat accumulated in the surface soil in summer and slowly released into the atmosphere, it is difficult to minimize the temperature of the near-surface air.

After the "winter solstice", although the days are getting longer and shorter, the days are still getting shorter and shorter, and the nights are getting longer and longer. The heat lost on the ground is still more than the heat absorbed, which makes the soil and near-surface air cool down day by day.

Before and after March 9th, the heat accumulated on the ground was the least. The cold air in Siberia frequently went south, and the temperature continued to drop, resulting in the coldest weather all year round. And this period happens to be in the solar terms of slight cold and great cold.

The origin of winter solstice

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.