Why scatter can polarize light?
Scatter happens because a photon excites an electron that absorbs its energy and vibrates, and this vibration re-radiates like an antenna a new photon in a random direction. The direction of the electron vibration is the same as the direction of the electric field of the incident photon. Conversely, the radiated photon has the electric field aligned with the direction of the electron vibration. Light is a transversal wave what means that the electric field “vibrates” perpendicularly to the direction of the beam. If the incident light is unpolarized, the electric field vibrates in every direction in a plane perpendicular to the beam. The electron of the scattering molecule will also vibrate confined to that plane. But if the plane is seen from the side, the vibrations appear to be confined to a line, as shown in this animation. Therefore, light scattered backwards (or forward) remains unpolarized, while light scattered at 90 degrees becomes linearly polarized (in intermediate directions
