With a close study of a separate snowflake can be seen that it is transparent. But snow that consists of thousands of thousands of transparent snowflakes, has white. How so it turns out?
The fact is that the light has a different wavelength. Each wavelength corresponds to its color. The distribution of colors by wavelengths can be viewed in the picture below.
Some materials can absorb the waves of a certain wave, while others reflect them. That is why objects have different colors. For example, some materials reflect short waves of blue, and the waves are longer absorbed, so we see the object of blue. Other materials are red, as they reflect only the wavelength characteristic of red color. The material reflecting all the waves falling on it will have a white color, and the material that absorbs all the waves will look black.
Snow, as you know, is frozen water. If you look at the water, you can make sure that it is transparent, which means that light waves pass through it. Therefore, there is nothing surprising in the fact that the snowflake is transparent. If you skip the beam of light through one snowflake, it will not affect, but, passing through the smallest ice crystals, it will challenge at an angle. No wonder they say: "There are no two identical snowflakes", because they all have a varied and unique form. When the beam hit on another snowflake, he will be loved again at any angle, then also also as long as it does not hit us on the retina, and our brain interprets the information obtained as white.
I just dropped and impurities that do not contain light waves refractals until they praise back, so it seems absolutely white. But sometimes even on pure snow you can notice some bluish shade. In this case, it all depends on the density of the dropped snow (if you exclude the presence of impurities). If it is loose enough, long light waves penetrate it a little deeper, while short, mostly blue, remain on the surface. We are just observing them.