Monday, January 22, 2018

The Season for Snowflakes

It's only January, but our parks have already experienced several winter storms. It's the perfect time to consider how snowflakes are created. The process begins when water vapor comes into contact with a pollen or dust particle in the sky. If it's cold enough, the water vapor freezes onto the particle and forms an ice crystal - the beginning of a snowflake. When the crystal becomes too heavy, it falls to the ground. As it is falling, water molecules continue to freeze onto it and the ice crystal grows into a full-fledged snowflake.

All snowflakes are hexagonal. Once the six-sided base is created, they develop their unique crystalline design in a process called branching. Warmer temperatures and wet conditions allow for greater, more complex branching. In colder weather, when temperatures dip below -7.6 degrees Fahrenheit and there is less moisture in the air, simpler branching occurs.

The first person to capture on film the intricacies of snowflake symmetry was Wilson Bentley, a Vermont native who was fascinated with snow from a  young age. Armed with a microscope attached to a camera, Bentley would stand outside in the snow for hours, choosing his snowflakes carefully so as to capture the most pristine specimens. In 1885, he succeeded and was the first person to photograph a perfect snowflake.

Today, we know that most of the snowflakes we see are imperfect. As a Park Naturalist, I was curious to see if I could capture a perfect snowflake like Bentley did. I stood on my porch in my black winter coat, with my smartphone in hand, and let the snow fall onto my outstretched arm. Alternating between first trying to spot a perfect snowflake with my naked eye and then hurrying to zoom in on my phone before the snowflake melted, the results were mostly indistinct blobs. But I finally succeeded. My best photo is below, showing one beautiful, perfect snowflake.

There are other types of precipitation here too: a clump of imperfect snowflakes (called an aggregate), maybe some sleet, and a raindrop. For more information, check out these websites and videos:

Written by Park System Naturalist Gage Sands