Did you catch the Google doodle today?  Google animated its logo to celebrate the 125th anniversary of the largest recorded snowflake.  This monster was nearly 15 inches across, observed January 28, 1887 at Fort Keogh, Montana.  In New York state, I once saw fluffy snowflakes that looked as wide as pancakes drifting gently from the sky.  It was awe inspiring.

Snow starts as simple hexagonal crystals.  Water droplets are attracted to the crystal, gathering and freezing especially at the corners.  The shapes change as the crystal falls through different conditions, forming the distinctive branched, six-sided snowflake shape we all know.

The crystals may freeze together forming snowflakes, if the temperature is near freezing and all conditions are right.  Larger flakes fall faster, crashing into and accumulating smaller flakes.  But if it's too windy, the fragile construction will blow apart.  That 15 inch record setter was a rare snowflake, indeed!

Learn more snowflake science at Kenneth G. Libbrecht's SnowCrystals.com.

Science Friday's video explains how snowflakes grow.