Although while polar bears usually look white, their fur isn’t white at all, it’s clear, and their skin is black.
Polar bear fur is:
The hair has light scattering particles inside. Sunlight travels into the hair and bounces around the hollow part of the hair causing a reaction called luminescence.
This luminescence is accelerated by the light scattering particles which disrupt the beam of light causing it to break up into more beams that are sent off in different directions. This is what causes whitish light to be given off by the hair, helping the Polar bear look white.
Polar bears pick up salt particles from swimming that also contribute to light scattering.
When UV rays from sunlight make contact with the bear’s dark skin it also produces a whitish color due to fluorescence.
A protein called keratin in the hair also has molecules that are slightly white in color and can add to the other effects happening with the fur.