What is the first frost?

1, the first frost is the last solar term in autumn, and it is also the solar term for the transition from autumn to winter. There is a lot of heat dissipation on the ground in autumn, and the temperature suddenly drops below 0 degrees. Water vapor in the air directly condenses on the ground or plants to form fine ice needles, and some become hexagonal frost flowers, which are white and loose in structure. Frost can only form on sunny days. People say that "thick frost is bad for the sun" is the truth.

2. The solar term of the first frost means that the weather is getting colder and first frost begins. The average temperature in the northeast, eastern Inner Mongolia and most of the northwest has been below 0℃, the soil has frozen, and the winter crops have stopped growing and entered the wintering period. To the south of latitude, the average temperature is around 16℃, and there are two or three solar terms before the first frost day. In the southern valley of South China, frost can only be seen in the dead of winter. Of course, even at the same latitude, the temperature and humidity of the air near the stratum are different because of the different altitude and topography, and the first frost period and frost day are also different.

3. "The first frost in the first frost" reflects the climate characteristics of the Yellow River basin. As far as the annual frost days are concerned, there are frost and snow in some parts of the Qinghai-Tibet Plateau even in summer, and the annual frost days are over 200, which is the place with the largest number of frost days in China. The annual frost days in eastern Tibet, southern Qinghai, Qilian Mountains, western Sichuan Plateau, northwestern Yunnan, Tianshan Mountains, Altai Mountains, western mountainous areas of northern Xinjiang, northeast China and eastern Inner Mongolia all exceed 100 days, and the vast areas south of Huaihe River, Hanshui River and east of Dongpo of Qinghai-Tibet Plateau are all below 50 days, with only the annual frost days in the south of 25 north latitude, Sichuan Basin, south of Fuzhou and coastal areas of Guangdong and Guangxi being/kl.