In most solid material, the particles re-emit most of the unabsorbed photons out of the material, so no light, or very little light, passes through and the object is opaque . The color of an opaque object is just the combination of the light energy that the object's particles did not absorb. To understand this, we need to back up and look at an individual piece of ice. This happens because the distances between some atoms in the ice's molecular structure are close to the height of light wavelengths, which means the light photons will interact with the structures. The result is that the light photon's path is altered and it exits the ice in a different direction than it entered the ice.
Snow is a whole bunch of individual ice crystals arranged together.
When a light photon enters a layer of snow, it goes through an ice crystal on the top, which changes its direction slightly and sends it on to a new ice crystal, which does the same thing. Basically, all the crystals bounce the light all around so that it comes right back out of the snow pile. It does the same thing to all the different light frequencies, so all colors of light are bounced back out. Inc. All rights reserved.