Why is Snow White?

I am assuming you aren't talking about that Disney chick; because if you are your sentence needs a predicate.

First of all, lets agree that snow is ice. Now imagine that you place a yo-yo in a cup of water, and then stick it in the freezer. Once it is frozen take it out and look at it. Inside the ice you can see the bright red yo-yo, or blue yo-yo if thats all you've got. That is because ice has no color, you can see right through to what is inside, like the yo-yo.

As we agreed, snow is ice. Therefor it is clear and has no color. Snow forms in clouds, and as it freezes parts of those clouds get stuck in the snow. All we see is the white fluffy cloud inside the snow/ice, just like we saw the colored yo-yo.

As further proof, melt the snow. As the snow melts the clouds escape and all you will have left is clear water. Unless there was a yo-yo in the snow. Yo-yos don't escape the same way, except maybe for the free range yo-yos.