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The Physics of Snowflakes

Adrian Bejan explains the physics behind the formation of a snowflake

It goes without saying that at least once this holiday season you can expect to hear someone utter the phrase, "No two snowflakes are alike." But just how accurate is that statement? Is it a solid fact backed by scientific proof, or upon further scruity does it fall apart like a snowflake under a microscope?

In the video below, Adrian Bejan, professor of mechanical engineering and materials science, explains the physics behind the formation of a snowflake. Using the Constructal Law of Design and Evolution in Nature, he details why each snowflake has the same basic shape despite a long and complex list of variables that can affect their formation. So does the common claim stand up to physics? The answer may surprise you.

As Bejan explains, a snowflake gets its shape from the temperature differences between the expanding ice crystal and the surrounding warmer air. And because the directions in which it can grow becomes more limited as it gets bigger, each individual snowflake invariably develops the same underlying geometry. What's more, the same theory can explain why other systems take the same basic shapes and patterns, such as the branches of a tree, the blood vessels running through your veins or a strike of lightening.

So the next time you're at a cocktail party and someone comments on the endless variety of snowflakes, you can correct them and tell them that the snowflake owes its shape and structure to scientific principles.