The first frost in the twenty-four solar terms.

The solar term of the first frost means that the weather is getting colder and first frost begins. In the south latitude Sichuan Basin, the average temperature is about 65438 06℃, and there are three solar terms before the first frost day. In the southern valley of the basin, frost can only be seen in the dead of winter. Of course, even at the same latitude, the temperature and humidity of the air close to the stratum are different due to the difference of altitude and topography, and the first frost period and frost day are also different. From a scientific point of view, the saying that "dew becomes frost" is not accurate. The frozen dew formed by dew freezing is hard small ice beads. Frost refers to the phenomenon of crop freezing injury caused by the sudden drop of temperature, and its harmful temperature varies with crops, varieties and growth periods. To form frost, the temperature of the ground or ground objects must drop below 0℃, and the water vapor content in the air on the ground should reach a certain level. Therefore, there may not be frost in first frost, and there may not be frost in first frost. However, due to the low temperature during frost, if the temperature continues to drop, it will easily lead to frost. After the first frost, a large number of Dioscorea zingiberensis were collected and excavated in our basin. If the harvest is too early, the lump will not fully expand, which will affect the yield; But if the harvest is too late, it may be damaged by early frost, and the block will be frozen and deteriorated, so it is very important to dig it out in time. Su Shi, a great writer in the Northern Song Dynasty, said in a poem: "There are thousands of trees to eliminate pornography, and only Furong is alone." The climate in Sichuan Basin is mild. During the first frost, the fields are lush, orange-yellow-orange-green, autumn chrysanthemums are in full bloom, and hibiscus trees are in full bloom, making the rich "Tianfu" even more gorgeous.