Are snowflakes always symmetrical

A.� Yes, they can’t help it. Their symmetry represents the organisation of water molecules as they crystallise from a liquid to solid state.

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Q.� More specifically

A.� As water molecules progress from a liquid to a solid state, a process known as crystallisation, they from weak bonds with one another. This formation, which maximises attractive forces and minimises repulsive ones, fills predetermined spaces in a specific arrangement.

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Once the first few molecules are in place, the pattern is set and all the following molecules must fir into predetermined spaces. The result is the basic symmetrical, hexagonal shape of the snowflake.

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Q.� If a specific arrangement is set, why are all snowflakes unique

A.� This is the theory behind snowflake formation, whereas in reality although snowflakes are symmetrical they're always unique.

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This differentiation occurs because each snowflake is a separate crystal and its formation is subject to the particular atmospheric conditions, mainly temperature and humidity, under which it is formed.

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Q.� Why are microscopic images of snowflakes so elaborate

A.� Basically because snowflake pattern is governed by atmospheric conditions that are complex and variable. Although a snowflake may start off under one atmospheric condition, that condition can change any second causing the snowflake to grow in a different way. The basic hexagonal symmetry remains, but the details of the snowflake can branch off in any direction.

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Q.� At what temperature does snowflake formation start

A.� Liquid water molecules begin to crystallise into a solid when the temperature drops below freezing

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by Lisa Cardy