Question

Why is the colour of clear sky blue? Explain in brief.

Answer 1

- Hint: The colour of sky is blue because the colour of shorter wavelength is scattered by the particles present in the atmosphere. We will explain it better in the solution given below.

Complete step-by-step solution -

The colour of the sky is due to the property of dispersion of light the white light of the colour before reaching the earth's surface gets dispersed into its 7 components VIBGYOR the molecules present in the atmosphere are capable of scattering only the light with the shortest wavelength and hence red light won't get scattered.
The molecules of air have size smaller than the wavelengths of visible light. They scatter light of shorter wavelengths more effectively than longer ones. Since the red light has wavelength about 1.8 times blue light. Therefore, when sunlight passes through the atmosphere the particles scatter blue light more than red and thus it reaches our eyes.
In points-
The blue colour of the sky is due to the scattering of the sunlight by the molecules present in the atmosphere.
The molecules of air such as and have sizes smaller than the wavelength of visible light. These molecules absorb more amount of sunlight and re-emit it, as sunlight passes through the atmosphere.
Blue light of shorter wavelength is scattered more strongly than red light of longer wavelength. This scattered light contains blue light in a larger proportion and it enters our eyes. That is why the sky appears blue.

Note: Duly remember the name of the particles due to which the rays are scattered in the sky. Writing the names down of the particles may help you a lot. Remember that the light of shorter wavelength is scattered effectively and not that of the longer ones.