• Question: Why is ice clear and snow white?

    Asked by imnotsureaboutbeardedhedgehogs to Andrew, Marianne on 24 Jun 2010 in Categories: .
    • Photo: Marianne Baker

      Marianne Baker answered on 24 Jun 2010:

      I think that’s to do with how closely packed together the water molecules are.
      In ice, they’re tightly together in a crystal-like structure.
      In snow, there’s a lot of little bits of ice just in a kind of pile with lots of air in between; and the air makes it opaque (opposite of clear).

      But, look at ice bergs; if you have enough ice and there’s enough air/dirt/other stuff in it, the light still can’t get through and instead it reflects white 🙂

    • Photo: anon

      anon answered on 24 Jun 2010:

      I didn’t know this but howstuffworks comes to my rescue again. See below

      http://science.howstuffworks.com/question524.htm

      I think there’s been a lot of trouble with the snow not being terribly white on Mont Blanc…Too many climbers, too many full bladders…

    • Photo: Andrew Maynard

      Andrew Maynard answered on 24 Jun 2010:

      Hi imnotsureaboutbeardedhedgehogs,

      It’s mainly to do with how light is diffracted (bent) at the edges between ice crystals and the air. In snow there are thousands/millions of ice crystals, and the light is bent all over the place – so everything just looks white. In ice that is reasonably pure, there aren’t so many edges, so the light goes right through.

      Of course, you can have white ice as well – which usually happens where there is air trapped in the ice – so again you have lots of places where the light has to travel between ice and air – and gets diffracted.

      ps – I’m not sure about bearded hedgehogs either!

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