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Ice with air in it

Why Is Snow White and Fluffy?

A snowflake is ice grown into a six-armed crystal, and snow is mostly the air between them.

1 Vapour freezesonto a dustspeck2 It grows sixarms3 Flakes pile upwith airbetween them
Frozen water, arranged very particularly.

  1. Step 1 of 5

    Snow skips the liquid stage.

    Rain Vapour → liquid → fallsSnow Vapour → ice, no liquidstage

    In a cold cloud, water vapour freezes straight onto a speck of dust. It never becomes a raindrop first — it goes gas to ice directly.

  2. Step 2 of 5

    It always has six arms.

    A snowflake Water molecules lock at120° — six directions

    Water molecules link at 120-degree angles, so the growing crystal can only branch six ways. Every snowflake obeys this without exception.

  3. Step 3 of 5

    Its shape records its journey.

    1 Grows in cold,dry air —plates2 Drifts intowetter air —branches3 The finishedshape recordsthe trip

    As a flake drifts through warmer and colder, wetter and drier air, it grows differently. The pattern is a diary of the air it fell through.

  4. Step 4 of 5

    Snow is white because of the surfaces.

    A single ice crystal ClearMillions of them White — light bouncesevery way

    Ice itself is clear. But a snowflake has thousands of tiny faces bouncing light in all directions, and all colours bounce equally — so it looks white.

  5. Step 5 of 5

    It is fluffy because it is mostly air.

    Fresh snow — airabout 90% airFresh snow — iceabout 10% ice

    Fresh snow is around 90 percent air trapped between spiky flakes. That trapped air is also why snow makes such a good blanket.

    Ten centimetres of fresh snow melts down to roughly one centimetre of water.

The short version

Snowflakes are six-armed ice crystals, and snow is white and fluffy because of countless surfaces and trapped air.

Try it yourself

Catch a flake on dark cloth and look with a magnifier before it melts. The six arms are visible with the naked eye.

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