When a snowflake lands on your sleeve, it's the end of a 20-minute tumbleweed journey through clouds. But its touchdown is not the end of the story. Grab a hand lens or magnifying glass and discover the Lilliputian world of snowflake watching, an easy, inexpensive hobby and a simple pleasure for all ages.
The life of a snowflake is a struggle for perfection and competition among fellow flakes. Contrary to popular belief, snowflakes are not frozen raindrops. They are born in clouds, pretty much out of thin air. Clouds form when water vapor condenses around tiny specks of dust or debris, much as a pearl forms around a grain of sand in an oyster. Once the water droplet freezes, ice condenses directly on its surface, and the snowflake begins to grow. Soon a hexagonal prism develops; arms sprout at the corners and plates grow on the arms.
Part of the fun of snowflake watching is trying to figure out how the different crystals grew into their various final shapes. If the tips are rounded, for example, humidity was high, allowing the arm to grow rapidly. If the tips are more angular and flat, that tells you the crystal fell through a cloud pocket of lower humidity, which slows the growth rate. And what about those random squiggles and wormy shapes you see all over the snowflake? These are bubbles, pockets of air trapped inside the crystal.
As a snowflake spins through the atmosphere, changes in temperature and humidity also define its shape. For example, the range between negative five and 15 degrees Fahrenheit is the ideal temperature for spawning the classic six-sided stellar dendrites (dendrite means "treelike"). Below negative five degrees, water saturation decreases and another classification of snow crystals appears: simple columns and plates.
While the six arms of a snowflake travel together, they grow independently. And many things can happen along the way to spoil a snowflake's perfect symmetry. In fact, the quintessential well-formed snowflake is quite rare. I've seen snowflakes shaped like teapots, hands, daisies and birds in flight.
Lopsided growth is caused by a variety of conditions, including structure defects and midair collisions with other crystals. If an arm begins to grow faster than its brethren, it outpaces them by "stealing" water vapor droplets that would otherwise add to their size. It's a dog-eat-dog world up there.
Sometimes, though, a snowflake's original identity is masked by small ice particles called rime. These warty cloud droplets collide with the snow crystals and freeze onto their surfaces, usually as the flake passes through a foggy patch in a cloud.
Whether you own a magnifying glass or a 35 mm digital camera, don't pass up a snowfall -- and get ready. Find yourself a scarf, fuzzy mitten or fleece jacket. Night, day, it doesn't matter. In the glow of a porch light or headlamp, when snowflakes appear, get into position under a roof awning. Then extend your apparel out in the falling snow, long enough to gather a few flakes. It's snow time -- have fun!
The world is full of beautiful things we overlook, with snowflakes near the top of the list. Snowflake watching is an outdoor adventure that will have you searching for treasure and can give you a refreshing, childlike appreciation of the natural world.