For many of us in the northern and mountainous regions of the country, winter isn’t truly here until that first liberal dusting of snow. We await the initial flurries in anticipation each year. Soon enough, we’re spending each bitter morning shoveling the walk and scraping off the car. But if we’re lucky — or persistent — we find hobbies, activities, and sports that help us to appreciate the season.
For so many of us, snow is a huge part of life for much of the year. But we don’t always think about the effects it has on our environment, our economy, and our traditions.
Upon closer investigation, snow affects us and our environment in so many more ways than we’d first imagine. From the types of snow crystals to the ski tourism it enables — there’s a lot more to snow than meets the eye.
Snow Science: What's in the Snowpack?
At first glance, it’s easy to think that snow is snow; it falls from the sky, lands on the cold, frozen earth, and hangs around until spring. But snow is a dynamic substance that not only comes in many shapes, styles and categories — it also undergoes constant change from the moment it begins to fall.
Not all flurries bring the same type of snow. We know this on a basic level, which is why we’ve come up with so many names for the stuff. Powder, corn, graupel, and sugar are just a few of the myriad categories we’ve come up with to describe different types and textures of snow.
Snow crystals form when water vapor condenses around a nucleus, like a dust particle in the air. As more water vapor condenses on individual droplets, the crystals freeze and grow, eventually falling toward the earth. The crystals can take on a plate- or column-like shape, depending on the conditions they grow in.
Stellar dendrites are the snowflakes of childhood fascination — the beautifully intricate, 6-point crystals we’ve all tried to cut out of paper. But some snow crystals are shaped like tiny needles, bullets, hollow columns, and prisms. With a simple hand lens, you can start to pick out some of these shapes.
Snow Metamorphism and Stability
While you may catch a glimpse of a perfect snowflake on your sleeve before it melts, you can be sure that crystals in the snowpack don’t retain their shapes for long.
To put it simply, different snow crystals form in different atmospheric conditions, and undergo metamorphism after they’ve landed on the ground. Snowflakes — either individual crystals or two or more crystals bonded together — fall from the sky and onto the snowpack.
As wind, temperature, humidity, pressure, and other weather conditions change, the crystals in the snowpack change in shape and size. Snow gets compressed as more snow falls on top of it. A simple pit dug into the snowpack reveals different “layers” that you can trace back through the season.
These snow layers are of big interest to backcountry skiers and travelers; depending on the arrangement and composition of the different snow layers, the snowpack has a certain level of stability — or instability. Stability tests, performed with a few simple tools, help backcountry travelers assess avalanche risk in the mountains.
For those who aren’t traveling through avalanche terrain, it’s easy to ignore (or forget) how dynamic the snowpack is. But for plants, animals, rivers, and streams, the changing snowpack deeply impacts the day-to-day.
Snow and the Environment
The amount, type, and longevity of snowfall has consequences beyond the ski slopes. In the West, snowpack contributes to water availability, river volume and velocity, irrigation, and the length and intensity of the fire season.
Snowpack also affects the plants and animals who live and survive in these winter environments. But unlike humans, plants and animals don’t have modern human comforts like down jackets and electric blankets — instead, they’ve adapted to the snow in some incredible ways.
Plants and Animals
Plants in cold climates must endure the challenge of being stationary, with no option to migrate. Many familiar plants have simple yet advantageous features that help them survive through heavy snowfall.
For example, many conifer, or cone-bearing trees, have very narrow profiles. Their conical shape and limber branches prevent snow from building up to dangerous, branch-crushing weights — rather, the load of snow slides off when it gets too heavy.
Some plants even benefit from the presence of snow. A good example is the sagebrush that covers much of the American West. In the winter, the snowpack acts as a sort of insulating blanket over the plants. A sagebrush plant’s evergreen leaves can absorb sunlight even from under the snowpack — and continue photosynthesizing into the winter.
Animals, unlike plants, have options for how they deal with the season’s snowfall. The choices? Migrate, hibernate, or resist.
Migratory animals, like many birds, avoid the snow, and — in the northern hemisphere — head south.
Animals like bears and ground squirrels hibernate or enter a state of torpor. This means that they slow down their metabolic processes through the winter season in order to conserve energy.
Resistors rely on their adaptations to endure the deep snowpack that characterizes their winter home. Big feet (like a snowshoe hare), hollow, insulative fur (like an elk’s), and shedding a brown coat for a snow-white one (like a long-tailed weasel) are all examples of adaptations that help animals deal with the snow.
Some animals, like wolves, even thrive in the winter. Their large paws and tendency to hunt in packs allows them to excel in the snow, while their prey tends to struggle.
Fire and Water
Snowfall and snowpack can greatly affect the ever-intensifying fire seasons and drought that much of the West has been dealing with in recent years.
But why, exactly, is the snowpack so important? Mountain snowpacks act like natural reservoirs of sorts. If you’re familiar with spring and early summer in the mountains, you know that all of the snow doesn’t melt at once. It starts to melt in lower elevations, and as the seasons progress, the snow line recedes higher and higher up the mountains. Colder temperatures at higher elevations hold water — in the form of snow — later in the season, gradually releasing snowmelt into streams and rivers.
In Aspen, this winter arrived on the tail end of a particularly dry summer. Rivers across the state of Colorado are low. As winter transitions to spring, then summer, the size of the snowpack contributes to how these water levels change. And according to climate forecasts, we’re looking toward shorter winters with less snow and higher precipitation — meaning fire seasons could get even more extreme.
In terms of water availability, snowpack contributes up to 75% of water supply in the American West. It’s easy — and unnerving — to think about how a smaller snowpack could affect water availability in mountain and desert towns in the coming years.
Snow, Culture and the Economy
Snow doesn’t just impact us on our daily ski laps and slushy commutes; it has far-reaching effects that have shaped cultures, traditions, and economies over many centuries. Think about wintertime in northern cities and towns — they’d be unrecognizable without the local ski lodge, sledding hill, and friendly neighborhood snowmen.
Humans have been living with (and thriving in) snow for millenia, with the advent of ingenious adaptations like dog sledding and snowshoeing. Our economies and traditions are deeply tied to our annual snowfall, perhaps in more ways than we think.
Ski Town Culture and the Economy
In mountain towns across the west, snow can be the center of the universe from early December to mid-April. Those who spend time in it - skiers, snowboarders, snowmobilers, and sledders — notice when it falls and when it doesn’t. Aside from eagerly anticipating the next pow day, we can be sure that snow matters in many other regards.
In countless ski towns, the shrinking snow sports season is affecting ski resort revenues. In turn, this shorter season affects the economy of ski towns that rely on tourism. Most jobs in these towns — whether within the resorts or at local restaurants, outfitters, and retail shops — rely on the winter tourists for a large percentage of their revenue. And as of 2017, Aspen Skiing Company was the biggest employer in Pitkin County, Colorado. Snow is more than just weather in these places — it’s the lifeblood.
The Future of Snow
It’s amazing how much we can interpret from the snow — past weather patterns, stability and avalanche risk, future runoff, and how plants and animals interact with it. All of this is complex and dynamic, and made much more so by the nuances brought on by climate change. The future of snow —- and everything and everyone who interacts with it — is uncertain. But we can take advantage now, to enjoy it, learn about it, and do what we can to fight the forces that threaten it.
It all goes back to playing our part in mitigating global climate change. Organizations like Protect Our Winters specifically dedicate energy and funding to preserving the environmental, economic, and cultural integrity of winter.
Start By Learning More
Snow is a fascinating part of winter — both here in Aspen, and around the world. From the ski resorts in the winter to the swollen rivers in the summer, snow affects so many aspects of our lives and environments.
If you’re interested in learning more about snow science and taking a closer look at the snowpack, we hope you will join us for a guided snowshoe or ski tour with an ACES naturalist. Learn more about our tours here.