During the winter months, snowflakes falling create excitement. Imagine everything covered in that white blanket of snow. As you stare at the winter wonderland, the question that often comes to mind is, “why is the snow white?”
Although it does not fit with the romantic notion of snow, the answer is actually quite scientific. It can be summed up into one word; light. Visible light is made up of different light frequencies. These light frequencies travel at different speeds and we see them as different colors. The colors we envision will depend on how material absorbs or reflects that light energy.
Each snowflake is an ice crystal. The saying that no two snowflakes are alike is not a myth. The make-up of each snowflake can vary, giving each snowflake its own unique shape. The individual ice crystals appear clear, almost like glass. They are not transparent, but translucent. The translucent appearance of ice crystals will partially reflect surfaces.
However, when you see a pile of snow, it is a bunch of these ice crystals all together. As each light photon passes through these ice crystals, the translucent material of the crystals changes the light’s direction. When a beam of light enters the snow bank, it will be scattered throughout the snow bank. The light can bounce from one ice crystal to another. The light photon may even come in contact with some air pockets in the snow bank. Eventually, the light photons will reflect back outwards.
All light frequencies go through the process of bouncing through the ice crystals. Regardless of the wavelengths of each light photon moving through the snow, it is all equally absorbed. When all the colors of light bounce back out to the surface, they all combine. All colors of the visible spectrum combining together will give a white appearance. Therefore, when you look at that snow bank, it does look white.
With all those ice crystals and air pockets making up the blanket of snow on the ground, it can have quite an effect on the light photons. All the light photons travel through the snow the same way. Sometimes the ice crystals absorb some light, giving the snow bank a different hue. However, for the most part, the light reflects off the snow bank, giving it the white appearance. The next time you walk through a pile of snow, admire how the light reflects off the ice crystals giving it the white appearance.
Source:
http://science.howstuffworks.com/question524.htm
http://www.discovery.com/area/skinnyon/skinnyon971003/skinnyon.html
