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MONDAY FEBRUARY 26 - WHY NO TWO SNOWFLAKES LOOK THE SAME
Before a snowflake ever lands in your yard, it really goes through quite an adventure,
and that helps justify the saying that "no two snowflakes look alike."
To get snow, you actually need minute particles of dirt or clay in the air -
typically, there might be dozens of these in every breath you take. Some of these
particles have a crystal structure that sort of resembles that of ice. Invisible water
vapor molecules in the air find that structure appealing, and at temperatures below
freezing, some of the water vapor freezes onto those particles. This starts the
process of making a
snow crystal. From there, the exact details of how the crystal
grows depend on the temperature and humidity of the air.
As these snow crystals fall, they can get roughed up. They might collide with each
other and break up into tinier pieces. Or if temperatures are near freezing, the
crystals may be coated with a thin film of water which acts a little like glue, so
they'll stick together when they collide, creating bundles of snow crystals that we
crystals complicated lifetime, the chances that any two will form in
exactly the same way are very very small.
Two snowflakes may "look" alike in a
general sense, but under a microscope,
the crystals, like human fingerprints,
will not be identical.