Why do autumn days seem high? Why is the autumn sky so high?

Autumn is often accompanied by light clouds, high skies and suitable temperatures in the morning and evening, so people often use the term "autumn is high and cool". So, how did such weather come about? In autumn, in the Northern Hemisphere, the sun gradually changes from direct to oblique rays around the summer solstice, with shorter daytime hours and longer nights.

During the day, the ground absorbs less heat from the sun's rays than in the summer, and less moisture evaporates from the ground into the air. In addition, with the gradual withdrawal of warm and humid air and the slow entry of cold air, and gradually occupy most of the provinces and regions of our country, the temperature begins to decrease, which will also reduce the evaporation of water vapor on the ground, therefore, there are fewer clouds in the sky, even if there are clouds, it is a light layer, and the visibility is very good. As a result, the sky is clear during the day and the sky is full of stars at night, making people feel that the autumn sky is particularly high.

Since the sky is clear during the day and the sky is not covered by clouds at night, the heat on the ground can be freely dissipated. The heat absorbed by the sun during the day is not enough to make up for the heat dispersed at night, so the temperature of the ground gradually decreases, but not much, so it is cold at first. At this time, people sweat less, and even if they sweat a little, the dry and cool air will make the sweat on people's bodies evaporate quickly, giving people a cool and comfortable feeling.

After the beginning of autumn, the warm and humid air that caused the hot and humid weather in midsummer has moved south and withdrawn from the mainland, while the cold air gathered in Siberia and Mongolia has invaded most of China's provinces in the south and driven away the original warm and humid air. In places occupied by cold air, in addition to the temperature dropping, the water vapor in the air also decreases, and the water vapor on the ground rises less, so the sky becomes clear and cloudless. As a result, the sky is clear during the day and the sky is full of stars at night, making the autumn sky feel particularly high.

In autumn, in the Northern Hemisphere, the sun gradually changes from direct hitting the ground around the summer solstice (June 21 of the solar calendar) to oblique rays, and the daytime time gradually becomes shorter, and the night time gradually increases. In autumn, the ground absorbs less heat from the sun than in summer, and the moisture evaporated from the ground into the air also decreases, so that there are fewer clouds in the sky, and even if there are clouds, it is a faint layer, and the visibility is very good, forming a blue sky scene, so the autumn sky looks so high!

In autumn, the dry, cool air from the north blows in, driving away the humid hot air. At this time, there is less moisture in the air, fewer clouds, and the sky is very bright. The weather is not hot, and people rarely sweat, so it feels much cooler.

1. After autumn, the sun in the northern hemisphere gradually changes from direct hitting the ground before and after the summer solstice to oblique radiation, the time of the day gradually becomes shorter, and the inner time of the night gradually lengthens, and the heat absorbed by the ground during the day is less than that in summer, and the moisture evaporated from the ground to the air is also reduced.

2. With the gradual withdrawal of warm and humid air and the slow entry of cold air, and gradually occupy most of the provinces and regions in China, the temperature begins to decrease, which will also reduce the evaporation of water vapor on the ground, so the sky is clear during the day and the sky is full of stars at night, making people feel that the sky in autumn is particularly high.