What should we pay attention to during the Great Cold Solar Terms?

     The climatic characteristics of the big cold solar term

    The Great Cold is in the second half of January in the Gregorian calendar, and in the second half of the December in the lunar calendar. The average temperature is minus 2-4 degrees Celsius, the minimum temperature is generally minus 14-17 degrees Celsius, and the extreme minimum temperature can drop to more than minus 20 degrees. The lowest temperature in half of the years occurs in this solar term. The maximum frozen soil depth is 30-40 cm, which is often the deepest solar term for the annual frozen soil.

     During the big cold solar term, the atmospheric circulation is relatively stable, and the circulation adjustment period is about 20 days. During such circulation adjustment, widespread rain and snow and strong winds often occur to cool down. When the west of 80 degrees east longitude is a long-wave ridge, and East Asia is a large coastal trough, my country will experience continuous low temperature under the influence of the northwesterly airflow and the constant replenishment of cold air.

    Minor cold and major cold are the periods of the year with the least rain. With the perennial cold and solar terms, the rainfall in most areas of southern my country only increased slightly compared with the previous period, 5-10 millimeters in most areas of southern China, and only 1-5 millimeters in the northwest plateau and mountains. South China is dry in winter, and overwintering crops consume less water during this period, and the contradiction between water supply and demand in farmland is generally not prominent. However, "don't blame the weather for the bitter cold, rain and snow, the snow will be left to next year's wheat". In the case of sparse rain and snow, it is undoubtedly beneficial to the growth of crops in Xiaochun by watering at the right time according to different farming habits and conditions in different regions.

    Vegetable Farming Arrangement for the Great Cold Solar Terms

    During the big cold solar term, the atmospheric circulation is relatively stable, and the circulation adjustment period is about 20 days. During such circulation adjustment, widespread rain and snow and strong winds often occur to cool down. When the west of 80 degrees east longitude is a long-wave ridge, and East Asia is a large coastal trough, my country will experience continuous low temperature under the influence of the northwesterly airflow and the constant replenishment of cold air. Like Xiaohan, Dahan is also a solar term that indicates how cold the weather is. Although modern meteorological observation records show that in some areas of my country, the big cold is not as good as the small cold, but in some years and a few places along the coast, the lowest temperature throughout the year will still appear in the big cold solar term. Therefore, we should continue to do a good job of crop protection against cold.

    Vegetables have freezing damage and cold damage. Freezing damage can be death from long cold, or short-term damage below 0°C; cold damage takes a long time, and generally requires a low-temperature weather process of more than 2 days. For example, rubber tree radiation type cold damage is more than 2 days. The type of cold damage is affected by the low temperature conditions of 5 to 10 days; the cold damage process takes a long time, generally in the low temperature weather of more than 3 days, such as the rice cold damage index is the temperature < 20 ℃, or < 18 ℃ for more than 3 consecutive days for the cold damage condition.

    Frost occurs when temperatures drop to <0°C for short periods of time during warmer periods and cause crop damage. There are two types of frost in our country, one is early and late frost, which occurs in warmer periods; the other is winter frost, which occurs in warm regions (tropical and subtropical) and occurs less frequently. Both are short-term hazards. Cold wave freezing damage is different from frost in that cold wave freezing damage occurs during cold periods and frost occurs in warmer climates. The temperature of cold wave freezing damage is lower, generally below -5℃; the temperature of frost damage is relatively high, generally above -5℃