Dave Miller
School Program Director
Keystone Science School
Freshly-fallen snow is a big part of what makes Summit County winters magical. It marks the excitement of winter holidays, school breaks and, of course, skiing and snowboarding. We spend a lot of time in the snow at Keystone Science School. Not only do we cross-country ski and snowshoe from our campus, but we look at snow up close and examine it on a scientific level. By doing this, we've learned that snow is much more than simply frozen water crystals that fall from the sky — it is a sophisticated world that changes with every footprint, gust of wind, temperature change and shift of atmospheric pressure. All of these changes create what is known as snow metamorphosis.
You don't have to be a scientist to understand something about snow metamorphosis. We all make observations about snow all the time without even knowing it. Have you ever noticed, for example, how sometimes the snow is just perfect for making a nice round, heavy snowball, whereas other times it refuses to stick together and just falls apart in your gloves? Or how sometimes when you ski the snow is really light and fluffy, but other times feels like you're plowing through wet cement? Here's how to tell what kind of snow is in your backyard:
Grab a magnifying glass and some kind of dark cloth (this could be as simple as the back of your gloves). Take a handful of snow and place it on the cloth, then gently shake it so that the flakes separate and you are able to view them individually. Take a look with your magnifying glass and describe what you see. Does the snowflake have several pointy sides? Does it have rounded edges? Does it look like a miniature pillar or column? Chances are that a snowflake in Summit County has pointy sides, which is classified as a faceted flake. Faceted snow is typically fluffier and produced in drier intercontinental regions such as Colorado and Utah. The other major type of snow, called round snow, is typically formed in wetter regions such as California and Oregon, and tends to create a thicker, more cohesive type of snowpack (ever heard the term “Sierra cement?”).
As the snow piles up on the ground, it continues its metamorphosis as it's affected by wind, melting and re-freezing. To see what we mean, try digging a snow pit. Take a small shovel or other utensil and dig a big trench of snow that goes all the way to the ground. Then use the edge of the shovel to smooth one wall of the trench from top to bottom. Now you can start to identify individual layers of snow, which can be created by high winds, melting and freezing, or new snow. To find the layers, take a thin tool (such as a popsicle stick) and run it down the smooth snow wall from top to bottom. Anytime you feel a difference in the snow (where it starts to get softer or firmer), mark that as a layer, working until you get to the ground. Then grab your magnifying glass and look at the snow grains found at each layer. What do you notice?
You've probably found that the layers contain snow grains of different types and sizes. For example, when water vapor rises from the warmer ground and freezes to faceted snowfall above it, large, loose grains knows as depth hoar can be created. Depth hoar is an indicator for avalanche risk, because it is creates an unstable, loose base for the snow above it which can lead to a large slide.
Snow science is important not only in determining whether the snow in our backyard will make a good snowball, but also in gauging travel safety. The exercise above is very similar to the one used by experts in charge of deciding whether an area is safe for skiing or travel. Remember to always check conditions before heading out into the backcountry. Enjoy the winter!
For more information, please contact Keystone Science School at (970) 468-2098 or visit us on the web, www.keystonescienceschool.org.
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