Why is the colour of the sky blue?

(N/A) The molecules of air and other fine particles in the atmosphere have a size smaller than the wavelength of visible light.
These particles are more effective at scattering light of shorter wavelengths (at the blue end of the spectrum) than light of longer wavelengths (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 the air scatter the blue colour (shorter wavelengths) more strongly than the red colour.
The scattered blue light enters our eyes,making the sky appear blue.