Why is there a sunset at night?

Colorful clouds often appear on the horizon around sunrise and sunset in the morning and evening. The morning glow and sunset glow are caused by the scattering of light by air. When sunlight enters the atmosphere, it will scatter when it meets atmospheric molecules and particles suspended in the atmosphere. These atmospheric molecules and particles themselves do not emit light, but because they scatter sunlight, each atmospheric molecule forms a scattered light source. According to Rayleigh scattering law, light with shorter wavelength such as violet, blue and cyan in the solar spectrum is most easily scattered, while light with longer wavelength such as red, orange and yellow has stronger light transmission ability. So we see that the clear sky is always blue, while the light above the horizon is only yellow, orange and red with longer wavelengths. After these rays are scattered by impurities such as air molecules and water vapor, the sky there will be colorful. As the saying goes, "Don't go out at dawn, travel thousands of miles at sunset", that is to say, the bright red sunrise in the morning indicates that there are many water drops in the atmosphere, which indicates that the weather is going to turn to rain. If there is a fiery red or golden sunset glow, it means that there is no cloud in the west, and the sunlight can be transmitted to form a sunset glow, which indicates that the weather will be fine. In the morning, the sun rises in the east. If there is too much water vapor in the atmosphere, some short-wavelength blue light, blue light and purple light in sunlight are scattered by the atmosphere, only red light, orange light and yellow light penetrate the atmosphere, and the sky is dyed red and orange, forming a sunrise. The appearance of Xia Hong means that the clouds and rain in the west will move, so "the morning glow never dies" and you see the sunset glow at night, which means that the clouds and rain have moved to the east and the weather will clear up, so "the sunset glow goes to Wan Li Road." Colorful clouds sometimes appear on the horizon around sunrise and sunset. The chardonnay seen in the eastern sky around sunrise is called morning chardonnay, and the chardonnay around sunset is called sunset chardonnay. Haze is the result of sunlight passing through the thick atmosphere around sunrise and sunset and being scattered by a large number of air molecules. When there are many impurities in the air, such as dust and water vapor, its color is more obvious. If there are clouds, they will also be dyed orange and red. The bright red glow before and after sunrise shows that there is already a lot of water vapor in the atmosphere, and clouds have invaded this area from the west, indicating that the weather will turn to rain. The appearance of a bright red and golden sunset indicates that the weather in the upper reaches of our western region has cleared up or the clouds have split, and the sunlight can penetrate to cause the sunset glow, indicating that the rain clouds hanging over the local area are about to move eastward and the weather will clear up.