Question

Why can't we see clearly through fog? Name the phenomenon responsible for it.

Answer 1

We can not see clearly through fog because the light is scattered by the droplets in the fog. Scattering is the interaction of light with particles which are comparable in size with its wavelength. The small particles of fog scatter the light in all directions. The number of particles in fog is too high, so this happens at a large scales. So the the light reflected from the object is not able to reach our eyes and hence we are unable to see any obstacle in our way.

A special case of scattering, i.e. backscattering is responsible for bouncing of the light from particles back to the same direction from which it came.

So the phenomenon responsible for less visibility in fog is scattering. Very fine particles scatter mainly blue light while particles of larger size scatter light of longer wavelengths. If the size of the scattering particles is large enough, then, the scattered light may even appear white. The particles of fog are large so it appears white.