Autumn equinox solar terms

The autumnal equinox is one of the twenty-four solar terms, and the time is generally from September 22nd to 24th in the Gregorian calendar.

The autumnal equinox is the sixteenth of the twenty-four solar terms. The time is generally from September 22 to 24 of the Gregorian calendar every year. On the day of the autumnal equinox, the sun reaches the longitude 180 (autumnal equinox), almost reaching the equator of the earth, and the length of day and night is equal all over the world (regardless of the refraction of the sun light by the atmosphere and the shadow in the morning). In ancient times, there was a saying that "the sun is sacrificed in spring and the moon is sacrificed in autumn", and the autumnal equinox was once a traditional "moon festival".

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.

The significance of autumnal equinox

First, day and night are equal. On this day, the sun reached the longitude 180 degrees, and directly hit the equator of the earth. 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.

Second, the climate changed from hot to cold. According to the division of seasons in ancient China, the autumnal equinox is called autumnal equinox from beginning of spring, Changchun, beginning of autumn and beginning of winter.