When is autumn in southern China?

Autumn, also known as autumn, is the third season of the year. The transition season from summer to winter is from September to 165438+ 10 in the northern hemisphere, from March to May in the southern hemisphere, and from the autumnal equinox to the winter solstice in astronomy. The standard for meteorologists to study phenology is: after the intense summer heat, the average temperature for five days is stable below 22 degrees, which means that it is autumn, and it is over when it is below 10 degrees.

There are six solar terms in autumn, namely beginning of autumn, Chushu, Bailu, Autumnal Equinox, Cold Dew and First Frost.

The temperature will gradually drop in autumn, but it is generally slower than in winter. Due to the difference of dry and wet conditions, there will be cold and rainy weather conditions or dry and cool weather conditions in different regions. In the cold late autumn, due to the large temperature difference between day and night, the water vapor transpiration during the day will condense at night, either dew or frost.

In autumn, the direct point of the sun gradually moves south from the northern hemisphere, passes through the equator after the autumnal equinox, and the sun directly shines in the southern hemisphere. Seen from the northern hemisphere, the angle of the sun gradually becomes lower, and the gap between day and night becomes smaller. At the autumnal equinox, the length of day and night is equal. In autumn, the distance between the earth and the sun is from far to near. Seen from the ecliptic plane, the sun is on the background of Leo, Virgo and Libra.

Beginning of autumn is the 13 solar term in 24 solar terms. On August 7th or 8th every year, beginning of autumn is considered as the time when the sun reaches 135. "Autumn" means that summer is cool, which means the beginning of autumn. But in early autumn, the weather in Jianghuai area is still very hot. According to the standard of dividing seasons according to the average temperature, it must be that the average temperature for five days is below 22℃ to be considered as autumn.

According to this standard, the Jianghuai area generally enters autumn in the middle and late September. After beginning of autumn, although the summer heat is hard to disappear for a while, there is still the afterglow of "autumn tiger", but the general trend is that the weather is getting colder and colder. The daily temperature range is gradually obvious, which is often very hot during the day and very cold at night.

Baidu Encyclopedia-Autumn