How does the weather affect the color of the earth's sky?

The influence of weather on the color of the earth's sky should start with the electromagnetic waves radiated by the sun and the earth's atmosphere.

Of the electromagnetic waves radiated by the sun, 43% are visible light that can be seen by human eyes. Visible light can also be subdivided into seven colors: red, orange, yellow, green, cyan, blue and purple. The visible light radiated by the sun is a mixture of these seven colors. The radiation wavelengths of these seven colors of light are different. Red light has the longest wavelength, followed by orange, yellow, green, cyan and purple, while violet light has the shortest wavelength.

When the electromagnetic wave radiated by the sun meets the earth's atmosphere, it will be scattered by atmospheric molecules. Red, orange, yellow and other colors have longer wavelengths and can be transmitted to the ground by bypassing atmospheric molecules. Violet and blue light with shorter wavelength will be blocked and scattered by atmospheric molecules. However, the human eye is not as sensitive to violet light as blue light; Purple light is more easily absorbed by the atmosphere than blue light; In addition, the sun radiates more blue light than purple light, so people see that the sky of the earth is blue.

In rainy days, the particle size of water droplets, soot and other particles in the atmosphere is much larger than the wavelength of visible light, so visible light of various wavelengths will be scattered or reflected. At this time, the intensity of sunlight decreases, so the rainy sky is gray.