How many months does autumn mean?

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. Meteorologists study the phenological standard, that is, when the five-day average temperature stabilizes below 22 degrees after the summer heat, it is considered as autumn and ends when it is below 10 degrees.

Extended data:

Autumn solar terms:

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

1, beginning of autumn

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.

2. Summer heat

Summer is 14 of the 24 solar terms. "Out" means going. In summer, the heat stops here, that is, in summer, the hot summer will pass, the temperature will gradually drop, and the rainfall will gradually decrease. But this is just a general rule, in the Jianghuai area.

There is a big difference every year. In some years, the weather during the hot summer is even hotter than that in summer, and the weather commonly known as "autumn tiger" has appeared. Because of this, the Jianghuai area interpreted the intense heat as "midsummer". Therefore, remind people to pay attention to heatstroke prevention at this time. The temperature difference between day and night in the north is gradually increasing, so it is necessary to add clothes in time in the morning and evening to prevent colds.

3.autumnal equinox

The autumnal equinox is a solar term representing seasonal changes. On the day of the autumnal equinox, the sun is located at longitude 180 degrees, and the sunlight is almost direct to the equator, and day and night are almost equal. At this time, the waiting temperature in the southern region has generally dropped below 22℃, and it has entered a cool autumn. "An autumn rain and a cold".

The cold air from the south meets the warm and humid air that gradually decays, which leads to repeated rainfall and the temperature drops again and again. In the northern part of the northwest plateau, the daily minimum temperature has dropped below 0℃, and you can already see the magnificent snow scene flying all over the sky and the earth wrapped in silver.

4, cold dew

Every year1October 8 or 9, when the sun reaches longitude 195, it is cold dew. "Twenty-four solar terms" said: "In September, the dew is cold and will condense." Cold dew means that the temperature is lower than that of the white dew, and the dew on the ground is colder and will soon condense into frost.

In the cold dew season, Nanling and the vast area to the north have entered autumn, and the northeast and northwest regions have entered or are about to enter winter. In the capital Beijing, you can see the first frost in many years. In addition to the perennial snow on the Qinghai-Tibet Plateau, it has generally begun to snow in the northeast and northern Xinjiang.

5. First frost

The solar term of the first frost is1October 23rd or 24th every year, 10. According to the "Twenty-four solar terms": "In mid-September, the gas is cold and condensed, and the dew is like frost." It can be seen that the first frost refers to the beginning of frost. However, China has a vast territory, and the climate varies greatly from place to place. "The first frost in the first frost" reflects the climate characteristics of the Yellow River Basin.

As far as the annual frost days are concerned, there are frost and snow in some parts of the Qinghai-Tibet Plateau even in summer, and the annual frost days are over 200, which is the place with the largest number of frost days in China.

The annual frost days in eastern Tibet, southern Qinghai, Qilian Mountains, western Sichuan Plateau, northwestern Yunnan, Tianshan Mountains, Altai Mountains, western mountainous areas of northern Xinjiang, northeast China and eastern Inner Mongolia all exceed 100 days, and the vast areas south of Huaihe River, Hanshui River and east of Dongpo of Qinghai-Tibet Plateau are all below 50 days, with only the annual frost days in the south of 25 north latitude, Sichuan Basin, south of Fuzhou and coastal areas of Guangdong and Guangxi being/kl.

Baidu Encyclopedia-Autumn