Question

What is the phenomenon responsible for the blue colour of the sky?

Answer 1

Scattering of light is the phenomenon responsible for the blue color of the sky. The molecules of air and other fine particles in the atmosphere have a size smaller than the wavelength of visible light. They are more effective in scattering the light of shorter wavelengths (blue) than the light of longer wavelengths (red). The red light has a wavelength about 1.8 times greater than blue light. Thus, when sunlight passes through the atmosphere, the fine particles in air scatters the blue color (shorter wavelengths) more strongly than red. The scattered blue light enters our eyes and sky appears to be blue.