Polar bear fur is not actually white, but mostly clear or transparent. The clear guard hairs of the polar bears coat scatter light, which creates luminescence and gives off a white-colored light. The fur appears white because it reflects all the visible wavelengths of light, rather than absorbing some of the wavelengths. The skin of a polar bear is black, and the hairs of the polar bears coat are hollow and colorless. The hollow hairs trap the light and bounce it around, creating luminescence, which gives off more white-colored light. The fur of a polar bear can take on a yellowish tinge from wear on the fur, and the time of year and changes in habitat can cause slight differences in the furs color, which helps them blend into their environment.