People often say' autumn is crisp'. What is the reason?

People often say' autumn is crisp'. What is the reason? The cool autumn is advancing, and the curtain of hot summer is drawn behind her. Since then, the sky is blue and the sea is blue, the wind is flowing, and the heart is cold or not. A picture of "Autumn Cool" began to splash ink. Autumn is not like the cold in winter, the noise in spring, or the scorching rain in summer. Autumn is like a fresh and ethereal fairy, but also like a modest and elegant gentleman, which makes people indulge in endless peace and comfort.

Especially in the north of China, Wan Li is cloudless and the air is fresh and transparent. During the day, the sun is beautiful and the wind is clear. At night, the moon and stars are bright. Autumn scenery, red leaves and yellow flowers, golden wind and golden fruit, flying frost and dew are refreshing. After concentrated "scouring" in summer and rainy season, the settling effect of particulate matter in the air is obvious, the dust and impurity particles in the atmosphere are greatly reduced, and the atmospheric transparency is greatly improved. In autumn, the air controlled by high-pressure descending airflow will also inhibit the upward movement of pollutants. Therefore, the air in autumn is the purest and freshest season.

Not only is visibility good in autumn, but the sky is bluer. Although the "crisp autumn" weather makes people feel very comfortable, the air is relatively dry after autumn, so we should pay more attention to hydrating in daily life to prevent dry skin and lack of water; Although the night after autumn is lengthened, due to the lack of "protection" of clouds, the average sunshine time and ultraviolet intensity have not decreased, so we must continue to take sun protection measures; Bring your eyes and your heart, enjoy the beauty of autumn and feel the magic of nature! In autumn, the sun becomes tilted, the days get shorter and the nights get longer. At this time, the heat absorbed by the ground from the sun is less than that in summer, and the water evaporated from the ground into the air is also reduced, so there are fewer clouds in the sky and the visibility is good, forming a blue sky.

In addition, when autumn comes, the temperature of cold air gathered over Siberia and Mongolia decreases, the water vapor in the air decreases, the water vapor rising on the ground decreases, the sky becomes clear and the clouds decrease. So the sky is clear during the day and starry at night, which makes people feel that the autumn sky is particularly cool.