Thursday, 24 December 2015

Christmas Science - Identical Snowflakes

Why are snowflakes always hexagonal and why are no two snowflakes ever the same shape?

Finally we make it to Christmas Eve and the last of my Christmas science nuggets. I hope you have enjoyed them and have not minded the occasional mention of my new book.

And so on to topic - why are snowflakes are always hexagonal and never the same?

This is a trick question as neither are all snowflakes hexagonal nor are they all unique. While many snowflakes exhibit some sort of six fold symmetry, in surveys it was found that only 0.1% were actually hexagonally symmetrical.

Depending on the temperature of formation the ice crystal that makes a snow flake could be needle shaped or columnar or the classic flat hexagon. Since the growing conditions of a snowflake will determine its final shape. And since these conditions vary minutely for each flake, they will probably all be different from each other.

But that does not mean they are unique, just that it is unlikely two are identical. Since we can’t look at every snowflake, we can’t say for certain that each one is unique. Although in 1988, Nancy Knight at the National Centre for Atmospheric Research in Boulder, Colorado discovered two hexagonal prisms that were, as far as could be seen, identical.

And lastly, just to say Happy Christmas and hope you have a great New Year. If you have any book tokens or Amazon vouchers, I have a suggestion...


  1. Good concepts of Christmas Science and Identical Snowflakes. As we know that now winter is running and almost everywhere snow. It's very enjoyable weather. Christmas has passed away with a lot of great memories. Well! I want to know about but it's good for me to have some useful information about Snowflakes.

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Science TV Presenter, live show performer, writer, strange prop builder and all round Science Bloke. All opinions expressed are mine alone. Not the BBC's, just mine.