Which one of the following is responsible for the blue colour of the sky ?

Correct option is A

The correct answer is: (a), Rayleigh Scattering
Rayleigh Scattering is responsible for the blue color of the sky.
Rayleigh scattering is a phenomenon where the molecules of the atmosphere scatter sunlight in all directions.
Shorter wavelengths of sunlight, such as blue and violet, are scattered more efficiently by the molecules in the atmosphere compared to longer wavelengths.
As a result, the blue light is scattered across the sky, making it appear blue to an observer on the Earth's surface.
This scattering effect is why the sky appears blue during the daytime, especially when the sun is overhead.
Information booster
Mie Scattering occurs when particles in the atmosphere are larger than the wavelength of light, such as dust, pollen, or water droplets.
Unlike Rayleigh Scattering, Mie Scattering affects all wavelengths of light equally.
Mie Scattering can produce various optical effects, including diffused light and halos around the sun or moon, depending on the size and composition of the scattering particles.
Nonselective Scattering refers to scattering where all wavelengths of light are scattered equally.
Unlike Rayleigh Scattering, which is wavelength-dependent and scatters shorter wavelengths more efficiently, nonselective scattering does not favor any particular wavelength.
Nonselective scattering can occur due to larger particles in the atmosphere, such as water droplets in clouds or haze, and can contribute to diffuse light conditions.
Ground Radiance refers to the light emitted or reflected from the Earth's surface.
While ground radiance can influence the overall brightness and color of the sky, it is not responsible for the blue color of the sky itself.