The Weather Notebook: Unique Snowflakes

Unique Snowflakes
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Hi, I'm Byran Yeaton and this is the Weather Notebook. Here's a question from one of our listeners in Buffalo, New York which, by the way, is the second snowiest city on average--in the United States.

Is it true that each snow flake is unique? I just came in from a snow fall with rod-shaped snow flakes. They all looked the same to me! Monica, Buffalo, NY

For many years, I have gone on the same premise as you, that no two snowflakes were exactly alike. So your question gave me a great impetus to look into the issue. According to meteorologist Frank Forrester, that thought apparently originated with American photographer named Wilson Bentley. After snapping thousands of snow crystals over the years, "Snowflake" Bentley claimed he had never seen two exactly alike.

Snow forms when water, which has a six-sided molecular structure, turns to ice in the atmosphere. But the temperature at which it forms has much to do with whether it forms a spike, or a rod, or many other shapes. It also follows a fractal pattern of development, which, from my (weak) understanding of mathematics, is a random development. So, theoretically, are there an infinite number of random patterns a snowflake could develop, or are there preferred patterns that several snowflakes in a billion could follow? No one whom I have read takes this on directly.

So in answer to your question, Monica, are no two snowflakes alike? Maybe. Once they fall to earth, the way they bind together, and the way they change over time determines their likelihood for avalanche, so scientists have put a lot of study into snow shapes. For a lot more in depth look at snowflakes, go to our website at weather notebook.org The Weather Notebook is a production of the Mount Washington Observatory and supported by the National Science foundation. :