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Artistry in Ice

Snow crystals fall in a stunning array of shapes and sizes. Whether admired for a fleeting moment or captured in time, each is a masterpiece of nature.

Photography by Kenneth Libbrecht

This "capped column" snowflake is representative of a flake's transition from a column to a plate.

Even with millions of snowflakes swirling about in a winter storm, the old adage that no two are exactly alike holds true. The intricate, icy doilies crocheted by Mother Nature are made unique by the constantly changing conditions of the atmosphere as they fall. Each crystal begins as a dust particle that gathers water molecules, growing at different rates according to the temperature. But even the most elaborate snowflakes generally take one of seven basic forms. The six arms of a stellar dendrite, for instance, branch off as though produced by a kaleidoscope. Another type, long, thin crystals, rain from the sky like needles. Spatial dendrites are disoriented jumbles of ice, and capped columns resemble squat barbells. Snowflakes also fall as flat sectored plates, hollow columns, and crystals specked with rime (frozen water droplets).

Of greater importance to plants and animals is what happens to snowflakes once they hit the ground, where the crystals begin to change in relation to the snowpack. If the pack is of equal temperature throughout, the crystals' tips evaporate and they become rounded. If the temperature differs from top to bottom, water vapor freezes onto the crystals, forming faceted, pyramidlike shapes. Facets trap more air, which makes the snow both warmer for the life beneath its surface and easier to travel through.

Fallen snowflakes begin to evaporate almost immediately, so photographing them is a fast art. Kenneth Libbrecht, a physicist at the California Institute of Technology who studies the growth of snow crystals, has spent the past two years refining how to capture them in time. He built his own photomicroscope: a digital camera, kept in a temperature-regulated enclosure, attached to high-resolution microscope objectives. Color filters illuminate the crystals' delicate structures. Libbrecht catches fresh snow on a piece of cardboard and uses the tip of a paintbrush to transfer choice crystals to a glass microscope slide. He snaps the photos while still outside. "One of the things I really like about photographing snowflakes is that you never know what you're going to find," he says. "You just take pictures of what nature provides and don't get to ponder it until you take it back inside."

Most of the crystals in Libbrecht's collection were photographed in Canada and Alaska. But there is a stunning assortment of snowflakes in your own backyard. Simply catch one on the dark surface of your sleeve and admire it through the lens of a magnifying glass. If you check several times throughout a given snowfall, you're likely to observe many of the seven basic types. Libbrecht likens snowflake watching to birdwatching, as they're both recreations involving the observation of nature. And like birding, he says, identifying snowflakes is "fine all by yourself but becomes much more fun if you have a guidebook." You can refer to Libbrecht's book The Snowflake: Winter's Secret Beauty (Voyageur Press) or download an abbreviated field guide at his website (www.snowcrystals.com).

—Jennifer Bogo