Why the colour of the sky is blue?
Step 1: Scattering of light.
When a ray of light is passed through a medium, it collides with the tiny particles present in medium because of this, some light rays get absorbed while other get scattered around.
Step 2: Reason for blue colour of sky.
As blue colour light rays scatters the most in atmosphere so these rays enters in our eye and we see the sky as blue.