Why is the color of the clear Sky is BLUE?

The molecules of air and other fine particles in the atmosphere have size smaller than the wavelength of visible light. These are more effective in scattering light of shorter wavelength at the blue end than light of longer wavelength at the red end. 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 wavelength) more strongly than red. The scattered blue light enters our eyes. If the earth had no atmosphere, there would not have been any scattering. Then, the sky would have looked dark. The sky appears dark to passenger flying at very high altitudes, as scattering is not prominent at such heights.

You might have observed that ‘danger’ signal lights are red in color. Do you know why? The red is least scattered by fog or smoke. Therefore, it can be seen in the same color at a distance.

Composed by- mathshater.