High temperature has withdrawn from "group chat", when can you feel the high air?

This summer, most parts of my country have gone through the hottest summer since 1961. The high temperature intensity of the region has reached the highest weather record. The Central Meteorological Observatory issued high -temperature warnings for 35 consecutive days to break the historical record; 40 ° C in Sichuan and Chongqing has been standard, and the highest temperature is comparable to Turpan; "Dest" ...

This year's high temperature is not only explosive, but also endurance. The cumulative number of high temperature days in Sichuan Basin, Jianghan, Jianghuai, Jiangnan, South China, Turpan Basin, Xinjiang is more than 20 days. It is more than 30 days.

(Image source: Veer Gallery)

Fortunately, Sanfu Tian has ended, and many places have also exited high -temperature "group chat". According to the forecast of the Central Meteorological Observatory, starting on August 31, the continuous high temperature weather process in the south will end, the summer heat fades, and the autumn high weather is just around the corner.

From the climate point of view, when will most parts of my country be autumn?

In fact, there are standards in autumn. In the meteorological sense, the standard of autumn refers to the average temperature of 5 consecutive days after Liqiu (August 7th), which is lower than 22 ° C for five consecutive days, and set the first day of the five days as autumn. Generally speaking, the earliest place in my country in autumn is Heilongjiang and northern Xinjiang, and autumn has been autumn in mid -August. In Beijing until early September, it started to feel like autumn. As for southern regions such as Jiangxi and Hunan, it will not be officially entered in October.

(Image source: Veer Gallery)

After entering the autumn, why is there a feeling of autumn high?

This is because the unique weather system in autumn causes the sky in the autumn to be higher and clearer.

As a transition season in summer to winter, the situation of solar radiation and atmospheric circulation has entered seasonal adjustment. The subtropical high pressure began to withdraw south, and the warm and humid airflow weakened. With the strengthening of cold air in early September, the low -level atmosphere in most parts of northern my country was controlled by the cold and high pressure of the mainland.

(Image source: Veer Gallery)

For high -level atmosphere, because the movement speed of the high -altitude weather system lags behind the ground system, the high altitude of the northern region is still under the control of the subtropical high pressure. Under the dual high pressure control of "upper warmth and cold", the prevalent sinking air flow greatly inhibits the possibility of precipitation. The sunny weather frequently "grab the mirror", which is very easy to appear the "screen blue" of blue and empty miles.

In addition, human respiratory dependence on the lung dependence and external air pressure of the outside world can cause pressure difference through the expansion of the respiratory muscles. If the external air pressure becomes low, the breathing will feel laborious, and it feels like "stuffy". In this season, the low -level atmosphere is controlled by cold and high pressure, which will bring people a "refreshing" feeling.

At the same time, the day is getting shorter and shorter during the day, and the solar radiation received on the ground is significantly reduced than summer. Due to the small clouds at night, the radiation from the ground to the atmosphere is more obvious. In this way, the heat absorbed by the ground during the day is not enough to make up for the heat emitted at night, so the temperature of the ground gradually decreases. Gradually dropped from 30 ° C to 20 ° C to 26 ° C, which is a more comfortable temperature.

Not only did the temperature decrease, in the early autumn, Mongolia's high pressure controlled the northern region of my country, but because the high pressure center value at this time was low and the pressure gradient was not large, the northern wind was not large. The cold wind of Xi, the sweat on the body also evaporated quickly, so it gives people a "dry" feeling.

After the autumn, the warm and humid air that caused the hot weather in summer has moved south and gradually withdrew from the mainland. The cold air gathered in the Siberia and Mongolia area was "eager to try". In the place where the cold air is occupied, in addition to the decrease in temperature, the water vapor in the air is also greatly reduced. In addition, the cold and high pressure "prevent" the ground water vapor rises. The humidity of the air in early autumn generally does not exceed 60%. Under this humidity conditions, the human body feels It's also dry.

(Image source: Veer Gallery)

In the end, the blue sky of Gao Yuan is also one of the reasons why the autumn is cool. After the concentration of the summer rainy season, the particlement drop effect in the air is obvious. The autumn air under high pressure sinking airflow control has also inhibited the rise of pollutants. Therefore, the atmosphere of autumn is the purest and the air is the most fresh in the four seasons.

The real autumn is coming, ready to feel good!

Produced: Popular Science China

Author: Liu Jia (China Meteorological News China Meteorological Propaganda and Science Popularization Center)

Producer: China Science Popularization Expo

The China Science Popularization Expo is the Science Popular Science Platform of the Chinese Academy of Sciences. It is sponsored by the Computer Network Information Center of the Chinese Academy of Sciences. Relying on the high -end scientific resources of the Chinese Academy of Sciences, it is committed to spreading cutting -edge scientific knowledge and providing fun science and education services.

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