Why is the autumn sky so high?

This is determined by the climate characteristics in autumn.

First of all, the days get shorter and the nights get longer after autumn. In the northern hemisphere, after entering autumn, the direct sunlight on the ground around the summer solstice gradually becomes inclined, and the time of day gradually becomes shorter and the time of night gradually becomes longer. During the day, the ground absorbs less heat from sunlight than in summer, and the water evaporated from the ground into the air is also reduced.

Second, after autumn, the temperature dropped. With the gradual withdrawal of warm and humid air and the gradual entry of cold air, and gradually occupying most provinces and regions in China, the temperature begins to drop, which will also reduce the evaporation of water vapor on the ground.

Together, the above two points show that there are fewer clouds in the sky, and even if there are clouds, they are weak layers with good visibility. As a result, Wan Li is clear during the day and starry at night, which makes people feel that the autumn sky is particularly high.

Extended data:

Climatic characteristics in autumn:

Generally speaking, in autumn, the solar altitude angle decreases and the temperature decreases; The autumn wind is cool, the summer heat is gone, the fruits are covered with branches, and the fields are golden.

In autumn, the summer monsoon gradually weakens and transits to the winter monsoon, with frequent cyclone activities, more precipitation on the front and great temperature changes.

It is easy to have intermittent rainy weather in early autumn.

In the Mid-Autumn Festival, controlled by the high-pressure weather system, it is easy to have clear Wan Li and sunny autumn weather, that is, the so-called "October Koharu" weather.

In late autumn, the influence of cold air in the north began to increase, and the conversion process between cold and warm weather and sunny and rainy weather was frequent, and the temperature fluctuated greatly.

References:

Baidu Encyclopedia-Autumn