FOLEY: The Simple Beauty of Snowflakes
Published: Tuesday, January 14, 2014
Updated: Tuesday, January 14, 2014 15:01
I wasn’t particularly crazy about the polar vortex swirling around the Midwest and the Northeast over winter break, but I do love a good snowstorm. I mean, who wouldn’t want a repeat of “Snowmageddon,” the infamous snowstorm that closed Georgetown’s campus for 10 days in 2010?
Yet, on a much smaller scale, the snowflakes that make up these snowstorms are perhaps just as fascinating as the storms themselves. There is a debate about whether or not the elaborate, six-pointed snowflakes of storybooks and construction paper cutouts actually exist. Researchers from Utah and the National Science Foundation took pictures of snowflakes reaching the ground with a camera they developed that has a shutter speed of one-forty-thousandth of a second — 20,000 times faster than the typical camera exposure. They found that, in reality, this type of “perfect” snowflake occurs only once in every thousand snowflakes.
That’s not to say that snowflakes themselves aren’t beautiful; an average snowflake just doesn’t exhibit the predictable beauty we expect. Snow is crystalized water that forms from clouds. As temperatures drop well below freezing due to low atmospheric pressure far away from the earth’s surface, the water vapor in clouds freezes around dust or pollen particles that also happen to be up there mingling. As the flakes fall to the ground, they pick up more frozen water vapor or dust on the particles.
The legendary flake image we have engraved in our minds comes from the idea that because water is a chemical, we should be able to predict its behavior on its way down from the sky. To a certain extent, this is true: Ice crystals form a shape that is called a hexagonal lattice. The most basic snowflakes will form this simple planar shape and then become a prism as they gain a third dimension.
But of course, it is nearly impossible to predict the exact way flakes fall from the sky. Before snow reaches your driveway, several variables affect the way it forms. First, there’s the temperature to consider: At relatively warmer temperatures, snow forms more needle-like structures. Colder temperatures induce the planar, six-sided flakes we like to make out of paper. Additionally, humidity plays a role in how the flakes are able to form. For example, if the tips are round and the arms of the flakes are long, then it was high humidity that likely allowed the flakes to grow rapidly. Irregular patterns can usually be attributed to pockets of air that become trapped in the ice. And there’s no telling what other particles the flakes may encounter on the way down that will alter their shape. In reality, most snowflakes end up looking like blobs because of the turmoil they encounter on the way from the cloud to the sidewalk.
Probably the foremost expert on snowflakes is professor Ken Libbrecht from the California Institute of Technology. As a young boy, Libbrecht spent almost every snowstorm outside using a magnifying glass to look at snowflakes. He attempted to speed-draw the different shapes he saw. For the most part, he succeeded: He created a general grid of 35 types of snowflakes that he observed falling. Today, he spends most of his time researching the particular circumstances that cause each type to form. He has also been working to create the perfect laboratory snowflake that exhibits the mythical six-point perfection.
While Libbrecht focuses on the microscopic aspect of snowflakes, we mostly encounter them on a landscape scale. Snow’s bright-white appearance can be credited to light chemistry. Because most snowflakes have so many surfaces, they reflect all colors, a phenomenon we perceive as the color white. And then there’s my personal favorite, the silencing factor: When the temperature’s right, snow coats everything with soft edges and absorbs the sound waves that normally fill our lives with background music. When snow is covered with freezing rain, however, it actually begins to amplify sounds.
Hopefully we’ll see a lot more of these complicated little flakes in the months to come. If anything, they seem to make the cold temperatures a little more bearable with their beauty.
Katherine Foley is a senior in the School of Foreign Service. CURIOUS BY NATURE appears every other Tuesday.