Phenological characteristics of autumnal equinox

In ancient China, the autumnal equinox was divided into three periods: "When thunder comes, the sound will stop;" Second, wait for scorpion blank households; Wait for the water to dry. "The ancients thought it thundered because the sun be the spirit is strong, and the yin began to fill after the autumnal equinox, so it didn't thunder. The word "blank" in the second phase means fine soil, that is to say, due to the cold weather, secluded small insects began to hide in Tibetan caves and sealed the hole with fine soil to prevent cold air from invading. " The water began to dry up "means that the rainfall began to decrease at this time. Because of the dry weather, the water vapor evaporates quickly, the water in lakes and rivers becomes less, and some swamps and puddles dry up.

In the autumn equinox, most parts of China have entered a cool autumn. The cold air from the south meets the gradually decaying warm and humid air, which causes repeated precipitation and the temperature drops again and again. As people often say, it's time for "an autumn rain and a cold", but the daily precipitation after the autumnal equinox will not be great. At this time, the field farming in the south and the north is different. In northern China, there is an agricultural proverb that says: "The white dew is early, the cold dew is late, and it is the right time to plant wheat in the autumn equinox." Proverbs clearly stipulate the sowing time of winter wheat in this area; And "White clouds come in autumn equinox, good songs and good rice seeds are everywhere" reflects the planting time of rice in Jiangnan area. In addition, the working people's taboos on the autumnal equinox solar terms are also summarized as proverbs, such as "The autumnal equinox is only afraid of lightning, how much is it?"

During this period, many parts of the country began to enter a period of less precipitation. After the autumnal equinox, the number of rainy days and rainfall in most parts of China, including Jiangnan and South China (except the rainstorm caused by tropical cyclones) entered a period of decreasing precipitation, and the water levels of rivers and lakes began to decline, and some seasonal rivers and lakes even dried up gradually. During this period, there may be individual tropical cyclones, but the impact location is south, mostly affecting the coastal areas of South China and Hainan Island. At this time, typhoons not only bring strong winds, but also bring rainfall, which is often beneficial to local soil moisture conservation, because these areas have turned into dry season after 10.