Why does the sky often appear white when it is foggy or cloudy in Beijing?
The scattering of radiation by larger particles is different from that by molecules. In the actual atmosphere, especially in the air near the ground, there are often many suspended solid and liquid particles, some of which are similar in size to the wavelength of light waves incident on them, while others are far beyond the wavelength of incident light. All wavelengths projected onto particles are scattered, and the incident light is white light, scattered light or white light.