Why is the fog red?

Reflection and scattering of light by suspended substances in the air. In foggy days, due to the reflection and scattering of light by suspended matter in the air, the speed of light with different wavelengths is different. After repeated reflection and scattering, visible light may be separated, that is, red suspended matter. Fog is a common weather phenomenon, which refers to water vapor condensate composed of water droplets or ice crystals suspended in the atmosphere near the earth's surface.