The twenty-four solar terms of heavy snow.

"Heavy snow" means that it begins to snow at this time. The winter climate in Sichuan Basin is mild, with little rain and snow. The average temperature is about 2℃ to 4℃ higher than that in the middle and lower reaches of the Yangtze River, and the rainfall accounts for only about 5% of the whole year. Occasionally it snows, mostly in 1 and February; Snow on the ground is hard to see once every three to five years. It is often an unforgettable pleasure to witness the snow-covered earth and the green trees wrapped in silver. "Xue Rui heralds a bumper harvest year" is an agricultural proverb widely circulated in China. In the north, a thick layer of loose snow is like covering wheat with a quilt to keep out the cold. The content of nitrogen compounds in snow is four times that of rain. Snow slowly melts and penetrates into the soil, which can increase the nitrogen in the soil and be easily absorbed and utilized by crops. The low temperature of snow water can freeze the overwintering pests on the surface and bring benefits to agricultural production. However, in the south, if the ground heat loses a lot on a sunny night after snow, there will be freezing damage, which will cause certain losses to crops such as peas and beans. The average temperature in our basin is still 8℃ to 9℃, and wheat and rape can still grow slowly, so it is necessary to strengthen field management to prevent freezing injury. During the heavy snow, the precipitation in the basin is mostly below 15 mm, and the western part of the basin is less than 5 mm, which is already a "dry winter" period. At this time, the climate of the basin is still foggy. Generally, 65438+February is the month with the most foggy days. Fog usually appears on cloudless nights or partly cloudy mornings. Meteorology calls it radiation fog. As the saying goes, "ten fogs and nine sunny days". Most of the fog will dissipate before noon, and the sunshine in the afternoon will be particularly warm.