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Asked by georgiawheelerxo to Charlotte, Colin, Becki, Rick on 27 Jun 2013.
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Rick Smith answered on 27 Jun 2013:
Well snow itself isn’t really white, it just reflects all the colours of light that shine on it because it is made of tiny crystals of ice that work like little mirrors. So since sunlight is white, it reflects the sunlight and looks white. If you shined a different colour light or laser onto snow in the dark then the snow would look like it was the colour of the light shining on it.
So when snow melts, it becomes water and the ice crystals aren’t there any more to reflect the light , so you can’t see the white colour anymore.
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Rebecca Scott answered on 27 Jun 2013:
Snow is frozen water and when the snow melts it reverts back to water. As Rick says, the crystals in the snow reflect the light back to us and appears white, but it isn’t really white…
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Charlotte Dalton answered on 27 Jun 2013:
Snow reflects the light in a slightly different way to ice as the crystals aren’t as perfect so ice is clear but snow is white, when the snow melts and turns to water the water doesn’t reflect light in the same way as the water molecules aren’t arranged as a crystal
Comments
Colin commented on :
The white appearance of snow is scattered light due to Fresnel reflection. That is when light travels from a medium such as air through one such as ice -some will be reflected back. There are many such air – ice interfaces in snow scattering the light at all different angles – thereby reflecting all the environmental light (such as from the sun, or cloudy sky) and hence it will look white. It would take on the appearance of the light illuminating it so shine a purple torch on it than it would appear purple.
When it has melted these air ice interfaces dont exist anymore – just one air water interface. Shine a torch on it and approximately 4% of the light will be reflected back (this depends on the angle you shine the torch though – I won’t go into that.