MP Board · Class 10 · Science · The Human Eye and Colourful WorldWhy does the clear sky appear blue during a sunny day?

The clear sky appears blue during the day because of the phenomenon of Rayleigh scattering of sunlight by the molecules of air and fine particles in the Earth's atmosphere. Molecules scatter shorter wavelengths of light, such as blue and violet, much more effectively than longer wavelengths like red and orange. Since our eyes are more sensitive to blue light than violet light, the scattered blue light reaches our eyes, making the sky look blue.