Frost Descent is the eighteenth solar term of the twenty-four solar terms. Douzhixu; the sun's longitude is 210°; the festival is held on October 23-24 of the Gregorian calendar every year. Frost's descent is the last solar term of autumn and the transition from autumn to winter. The characteristics of the frost solar term are that the weather is colder in the morning and evening, and hotter at noon. The temperature difference between day and night is large, and autumn dryness is obvious.

Frost falls between October 23rd and 24th in the Gregorian calendar every year. It is the eighteenth solar term among the twenty-four solar terms. At this time, the sun reaches 210 degrees of ecliptic longitude. Frost is also the last solar term in autumn, and the temperature in many places has dropped to 0 degrees. The water vapor in the air freezes into frost on the ground, creating the shapes of small ice needles and hexagrams. The numbers also began to fall, and the insects stopped eating and began to prepare for hibernation.

Wu Cheng, a scholar of the Yuan Dynasty, compiled "The Collection of the Seventy-Two Hours of the Moon Order". He divided the frost into three seasons: the first period is for jackals to sacrifice animals; the second period is for yellowing of vegetation; the third period is for stinging insects. Bow. At this time, animals such as jackals begin to capture prey for the winter; leaves turn yellow and fall; hibernating animals also hide in holes and enter a state of hibernation without eating.

Farming activities

After the frost solar term, cold air activities become more frequent, and the temperature difference between day and night becomes larger. The "Frost Descent" solar term has nothing to do with "Frost Descent". It does not mean that "Frost Descent" will occur when entering the Frost Descent Solar term. In fact, "frost" does not fall from the sky, but is caused by the condensation of water vapor on the ground when it encounters cold air due to changes in temperature.

There is no concept of "frost" in meteorology. Generally speaking, the first frost in autumn is called "early frost" or "first frost", and the last frost in spring is called "frost". "Late frost" or "final frost"; the interval from the last frost to the first frost is the frost-free period.

At the time of frost, most areas in the north have finished their autumn harvest. Even cold-resistant onions cannot grow any longer, because "frost cannot afford onions, and the longer they grow, the more space they need." In the south, it is the busy season of "Three Autumn", when single-season hybrid rice and late rice are harvested, early-cropping wheat is planted, early-cropping rapeseed is planted; cotton is picked, cotton stalks are pulled out, and the land is plowed and prepared.