What time period is autumn?

September to 165438+ 10 in the northern hemisphere, March to May in the southern hemisphere, and the autumnal equinox to winter solstice in astronomy.

Meteorologists study phenology according to the following criteria: after the summer heat, the five-day average temperature is below 22 degrees for autumn, and it ends 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.

Extended data:

Beginning of autumn is the 13 of the 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.

References:

Baidu Encyclopedia-Autumn