Video shows how snowflakes form

As you gaze out the window at the falling snow, or watch it on TV, marvel at the fact that every one of the trillions of snowflakes that makes up a blizzard is unique.

Scientists have learned a lot about how snowflakes crystallize. Each flake starts as an individual speck of dust in the atmosphere, then moisture clings to the dust, the droplet freezes and crystallization begins. As the American Chemical Society explains in the video below, there's a precise science behind why snowflakes develop their distinctive six-pronged shape.

A cavity forms in each side because ice grows fastest along the edges, and from there six branches sprout. The branch tips grow and then narrow as temperatures hit the -13 Celsius mark. Another degree colder, and side branches sprout. Subsequent blasts of warmer and cooler air leave their imprint on the branches as the snowflake falls toward Earth. Scientists now classify snowflakes into 121 categories, based on the arrangement of atoms that result in different shapes.

Watch the video to see how it works: