Explain polarisation by scattering.

(N/A) When sunlight enters the Earth's atmosphere,it encounters molecules that scatter the light in different directions. This phenomenon is known as scattering.
Consider unpolarised sunlight incident on a molecule. The incident light has electric field oscillations in all directions perpendicular to the direction of propagation. In the figure,dots represent oscillations perpendicular to the plane of the figure,and double arrows represent oscillations in the plane of the figure.
Under the influence of the electric field of the incident wave,the electrons in the molecules are set into oscillation,acquiring components of motion in both these directions.
If an observer looks at the scattered light at an angle of $90^{\circ}$ to the direction of the incident sunlight,the charges accelerating parallel to the double arrows (in the plane of the observer's line of sight) do not radiate energy towards the observer because their acceleration has no transverse component relative to the observer's line of sight.
Therefore,the radiation scattered towards the observer consists only of oscillations represented by dots. This means the scattered light is polarised perpendicular to the plane of the figure. This explains the polarisation of scattered light from the sky.
The scattering of light by molecules was investigated by $C.V.$ Raman and his collaborators in the $1920s$. Raman was awarded the Nobel Prize for Physics in $1930$ for this work.