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| Earth on Dec 12, 2009

Are two snowflakes ever the same?

Many billions of snowflakes drift down to Earth’s surface in the course of a winter. Some are the lacy or star-type snowflakes. Others are what scientists call ‘columns.’

Snowflakes are crystals. You could see them in many different shapes if you let them fall on a black surface and looked at them with a magnifying glass.

But not all snowflakes are the lacy or star-type snowflakes you see in pictures. A range of different basic shapes form at different temperatures, so the kind of snowflake depends on the temperature of the cloud in which it formed. Relatively warm clouds yield lacy or starry snowflakes. Very cold clouds yield snowflakes known as “columns.”

We’ve all heard that no two snowflakes are alike, and that’s true of the star-shaped ones.

On the other hand, column-type snowflakes have simple, solid prism shapes – much as if you cut a section out of a lead pencil. While the ratio of their length to thickness can vary, column-type snowflakes don’t have a complicated structure. Many are very much alike.

On the other hand, even these column snowflakes aren’t identical when you look closely – at the level of the snowflake’s molecules. The expert we talked to said, “I don’t know why people pick on snowflakes – are any two geraniums alike? Or kittens, or mountains, or asteroids?”

Our thanks to:
Dr. Charles Knight
National Centre for Atmospheric Research
Boulder, CO