Brief introduction of climatic characteristics of severe cold solar terms

1. Climatic characteristics of severe cold solar terms: rain, snow, strong wind and low temperature.

2. The severe cold occurs in the second half of Gregorian calendar 1 month and the second half of lunar calendar1February, which is the last solar term of the lunar calendar. It means that the coldest time of the year has arrived, but the temperature gradually rises from low to high, often higher than the last solar term. The average temperature is -4℃, the lowest temperature is generally-14- 17℃, and the extreme minimum temperature can be reduced to more than 20 degrees below zero. The lowest temperature in half a year appears in this solar term. The maximum frozen soil depth is 30-40cm, which is often the solar term with the deepest frozen soil in a year.

3. During the severe cold solar term, the atmospheric circulation is relatively stable, and the circulation adjustment period is about 20 days. When this circulation is adjusted, there will often be a wide range of rain and snow weather and strong winds to cool down. When the west of 80 degrees east longitude is a long wave ridge and East Asia is a coastal trough, under the influence of northwest wind and constantly supplemented cold air, China will have a sustained low temperature.

4. During the year-round severe cold solar terms, the rainfall in most parts of the south only increased slightly compared with the previous period, with 5 ~10mm in most parts of the south and only1~ 5mm in the mountainous areas of the northwest plateau. During the winter drought and the overwintering of crops in South China, the water consumption is small, and the contradiction between supply and demand of farmland water is generally not prominent. However, "if you are bitter and cold, don't complain about the rain and snow. Snow is reserved for next year's wheat." In the case of scarce rain and snow, it is undoubtedly beneficial to the growth of early spring crops to water in different areas according to different farming habits and conditions.