How to enter autumn?

According to the lunar calendar, "beginning of autumn" is the beginning of autumn and ends with "the first frost". The vernal equinox is only half of the 90 days from beginning of autumn to the first frost. Therefore, according to the autumnal equinox theory of China's old calendar, this day is exactly half of the ninety days of autumn, and what we usually call autumn begins with the autumnal equinox.

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?"

The significance of autumnal equinox

1, the equinox begins with equal time between day and night. On this day, the sun reached the longitude 180 degrees and hit the equator of the earth directly. Therefore, in most parts of the world, 24 hours are divided equally between day and night, each being 12 hours.

After the autumnal equinox, the direct point of the sun began to enter the southern hemisphere from the equator, and the northern hemisphere began to have shorter days and longer nights, and the day began to be shorter than the night. Near the North Pole, there are long nights and stars for six months in a year.

2. The climate changes from hot to cold. According to the division of seasons in ancient China, which started with beginning of spring, Changxia, beginning of autumn and beginning of winter, the autumnal equinox is divided into 90 days in autumn and divided equally in autumn.