GYE Nature News #22 Feb 18, 2021

Intro to living and safety in the snow….

The word snow can be defined by many different words in many different languages and in multiple forms. For those of you in the Northern Hemisphere experiencing yet one more unpredictable winter, (La Nina effect is hitting us, but a bit later than expected) we recognize temps, humidity, snowfall and wind are all coming together in one big cold mid winter! Depending on our geography it will hit us all differently now, but here in the mountains the weather events since November have set up some considerable avalanche conditions.

layers in the snowpack, north cascades institute

This can be determined by looking at the history of this season’s weather events and what the snowpack looks like on the ground. Snow is not only impacted by atmospheric phenomena, but as it falls from the sky to us on the ground it goes through a series of “life changing events” . Think of snow as staring as water vapor that has ascended from the surface . This hit a layer of air cold enough to form ice crystals. The crystal form depends on many different factors. We think of the classic “snowflake” or stellar crystal with 6 legs and a lacy appearance.

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Hoar Frost crystals

For more on this one must learn about “Snowflake Bently”.

When snow hits the ground, everything changes depending on ground and air temperature, wind direction and speed and even the aspect of the surface where the snow starts to deposit.

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Depth Hoar on bottom of snow pack creates an unstable base photo by Andrea Saari

It changes depending on the same factors I just mentioned and how the weather and atmosphere works together through the many weeks of winter.

For the purpose of this story, not too much detail will be shared but if you are interested, there is so much cool snow science and story out there.

Snow is significant in Greater Yellowstone for more than recreation and beauty, but also as the significant source of ground and surface moisture. It is also a driver of many different behaviors and processes for life in this ecosystem. Wild lives here survive winter by adapting to cold and snow, migrating to a different climate or hibernating. Many life forms adapt to these conditions.

Bison in the snow

For now, let’s go back to what happens to snow when it falls from the sky, collects on the ground and is influenced by many different factors. As snow accumulates on different aspects, in different temperatures and at different rates, it builds up in unique ways. An example of this is when early snow falls on a warm ground and the temperatures continue to get very cold, the vapor from these early flakes rises into the upper layers and the bottom layer forms unconsolidated , non uniform and non bonding crystals called Depth Hoar. This can cause a very unstable base at the bottom of the snow pack. It can also form between icy layers through out the snowpack. Air pockets are numerous between these crystals and as snow accumulated above this layer and acts like an insulator, it does create a great system of living spaces for birds, insects and small mammals to retreat to in the coldest of conditions. Snow is one of the shapers of Greater Yellowstone.

possible “Subnivean” profile

Those more consolidated layers of insulating snow may not set up good foundation for snow stability, however. This is the kind of puzzle that snow scientists and avalanche forecasters are putting together as they dig though the snowpack in different locations around the Yellowstone Ecosystem to try and publish a forecast for potential avalanche conditions on a day to day basis.

Last weekend, Big Sky Adventures and Tours hosted a training for employees. We spent 3 days, mostly in the field, but some time inside learning the basics of snow/weather and the physical science of snow and avalanches. Anyone who recreates in the winter landscape would benefit from this, but it also helps us understand how weather and snow impacts wild lives in this climate. Hayden, our instructor shared multitudes of info as a “snow historian” and how to gather and interpret that information. We then went to the backcountry for 2 half days and 1 very full day, all starting at temps below 0 F.

Chris analyzing a snow pit
Andrea and Kate checking the “Alpha angle” of a slope
Our group and a “sun dog” at the end of a cold day, Andrea Saari

Why is this important? As I said earlier, all the lives that depend on the GYE are dependent on snowfall as an ultimate water source. Much of the year this area is covered with snow and the reason we have the rivers and groundwater we do is because of that. How will climate change affect us down the road? Again, a topic for another nature news.

Trumpeter Swans migrate from the north for the open water due to thermal influence

Many more people than ever are recreating in the wild places in all seasons. The trend since covid has increased greatly. Something I feel strongly about is for those who get outside, any season, recognize they are in the sanctity of the natural world. These places have so much to offer our hearts and souls, as well as our adrenaline junkie fixes. I know anyone who is here feels that peace of the wild places. The challenge is to recognize how we fit into this place and how we can be here safely.

Winter offers opportunites for peace and solitude

Winter is it’s own palace and anyone who can experience wild places in winter must recognize vulnerability for themselves and all that dwell here. We may need to say away from some of these places some of the time for our own safety. For now La Nina is upon us and we are getting snow. The characteristics of snow are obvious every where we look. .

Lower Falls of Yellowstone River

Enjoy the beauty of winter, it will fill your soul. Be prepared if you are traveling into the backcountry.

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  1. Leslie this looks great. I received the Web $ in the mail yesterday thank you for that! I hope you are getting other good feedback on the posts and emails they have come a long way and very interesting. I usually forward them to others and get complimentary replies.

    Hope you are having a good week then weekend,


  2. So informative! And always great photos!

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