Why Six-sided Snowflakes?
I would like to know how the geometry of the water molecule
leads to a six-sided snowflake. When someone asked me this
question, I could not answer , despite years of physics.! Thanks!
It is not so much the geometry of the water molecule that determines
the shape of snowflakes as the geometry of ice - water in ice
orients itself in such a way that a six-fold rotational symmetry
is generated, and the very tiny ice crystals that are the beginnings
of snow flakes will exhibit this six-fold symmetry. If conditions
are consistently right as the snow-flake grows (so that surrounding
water molecules settle on it in a symmetrical fashion) it
should preserve this symmetry. However, I have seen an awful lot
of snow in my life, and I do not think I have ever seen a snowflake
that was really very symmetrical (they are often very flat, which
is explainable in standard crystal growth theory, but retaining
perfect six-fold symmetry is kind of hard to explain).
Click here to return to the Physics Archives
Update: June 2012