Why is there a sunrise in the sky?

In the morning, the sun rises in the east. If there is too much water vapor in the atmosphere, some blue light, blue light and purple light in sunlight will be scattered by the atmosphere. Only red light, orange light and yellow light penetrate the atmosphere, dyeing the sky red and orange, forming a sunrise.

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.

Why the sunset glow is red: colorful clouds often appear on the horizon before and after 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.