Polar bears are not white. Their skin color is surprisingly jet black. However, they usually appear white to us humans.
Now the question is, why do they appear white??
The concept that explains their white appearance is quite simple and is known as reflection.
Reflection, as we know, is bouncing back of light similar to the bouncing back of a ball when thrown straight to the ground. Reflection has many types, one of which is called diffused reflection. Reflection of light from an uneven surface, such as the skin of a polar bear, is known as diffused reflection.
This diagram will help you picture it.
The fur of a polar bear is transparent and hollow. These unique characteristics give light enough space to reach the surface and reflect. Polar bears appear white because their fur reflects all the visible light.
They even appear green if kept near algae.
Scientists believe that the hollow hair gets filled with algae, making the polar bear appear green.
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