Can you predict the shape of a snowflake?

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Offline thedoc

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Can you predict the shape of a snowflake?
« on: 11/10/2012 23:30:02 »
Harvey Shaw  asked the Naked Scientists:
Hello my name is Harvey Shaw and I have a question.

I know all snowflakes have totally different shapes, I want to know, can you predict a shape of a snowflake, or how many could fall.

Thank you very much, I look forward to hopefully hearing from you.

What do you think?
« Last Edit: 11/10/2012 23:30:02 by _system »


Offline evan_au

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Re: Can you predict the shape of a snowflake?
« Reply #1 on: 14/10/2012 05:19:10 »
The amount of snow is predicted quite regularly by weather forecasters - probably with similar accuracy to every other prediction they make (which is to say, their predictions are getting better, for a longer period into the future, due to better data collection and more powerful computers running better weather models).

There are many basic forms of snow crystals, influenced by slight changes in temperature and humidity, including plates and bars. Many of them have hexagonal symmetry, although 3 and 12 sides are also possible.

If a group of snow crystal is grown in constant conditions, they will all have one of these basic, predictable shapes.

However, natural snowflakes circulate through a cloud on windcurrents, and are exposed to many different environments in rapid succession, resulting in random cycling from one crystal growth pattern to another. Two adjacent snowflakes on the ground will have taken quite different paths through the clouds, resulting in a very different set of crystal patterns.

The hexagonal symmetry of the classic snow crystal is due to the fact that the "arms" of a crystal are bound together; all 6 arms then take the same path through the cloud, resulting in the same sequence and duration of crystal growth patterns on each of the 6 arms.

It is the random path through randomly varying conditions which makes the shape of a particular snowflake unpredictable.