Excuse me, why is it sometimes so cold and sometimes so hot? Pray for the great gods.

First, because the northern part of China is far from the equator in winter, it gets less heat; Second, the northern region is affected by cold air from Siberia and the Arctic Ocean in winter, so it is vulnerable to cold air attacks, so the winter temperature in the northern region is low and the weather is cold. The earth's orbit around the sun is elliptical, not circular. Therefore, when the earth revolves around the sun for one year, there will be times when it is closest to the sun and times when it is farthest from the sun. The nearest is summer, and the farthest is winter. Often basking in the sun in winter is of great benefit to increase human blood circulation, improve hematopoietic function, regulate central nervous system and enhance metabolism and immune function of various parts of human body. In a winter day, there are three periods that are most suitable for sunbathing. The first stage is 6-9 am, during which the infrared rays of the sun peak, which can promote blood circulation and remove blood stasis. The second stage is 9- 10 in the morning, and the third stage is 4-5 pm. Irradiation in these two periods can promote the absorption of calcium and phosphorus in the intestine and promote the normal calcification of bones.