Why is snow white?

A fresh blanket of snow is one of the most familiar images of winter: bright, sparkling, and pure white. It seems so obvious that snow is white that few people ever question it. But there is actually a puzzle hiding here. Snow is made of ice, and ice is made of frozen water. Water is clear and colorless, and a single ice cube is see-through, not white. So how does a pile of frozen, clear water end up looking brilliantly white?

To solve this puzzle, it helps to understand how we see color at all. Sunlight, which looks white, is actually a mixture of all the colors of the rainbow combined. When light strikes an object, the object usually absorbs some colors and reflects others. The colors that bounce back to our eyes are the colors we see. A red apple, for example, absorbs most colors but reflects red. An object that reflects all colors equally back to our eyes appears white.

A single ice crystal is clear, and light passes through it, bending slightly. But snow is not a single crystal. Snow is made up of a huge number of tiny ice crystals piled together, with countless surfaces and lots of air pockets between them. When light enters this jumble of crystals, it does not pass straight through. Instead, it bounces, bends, and reflects from one crystal surface to another, over and over again, in a process called scattering.

Here is the key point. As light bounces around among all those ice crystals, the crystals do not favor any particular color. They scatter every color of light equally well. So when the light finally bounces back out of the snow toward your eyes, it still contains all the colors of sunlight mixed together. Since all the colors combined are seen as white, the snow appears white. This is the same reason clouds, which are also made of countless tiny water droplets or ice crystals, look white too.

This article was written using information from Wikipedia.