Why are there morning glow and sunset glow?

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 \x0d\ 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 show gorgeous colors. 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.