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Mysteries: San Juan Snow Spirals

November 23, 2009 Ski, Wild 6 Comments

Michael Barton, owner and head guide  of Mountain Goat Ski Guides in Silverton, sent us this note about mysterious movements in the snow:

There’s a regularly occurring phenomenon that is a great mystery to this ski guide. Despite my schooling in science and having apprenticed for five years with world-renowned snow master Chris Landry, I cannot seem to figure this one out. I will open the floor for debate, and maybe someone out there in the world of snow-wandering mountain peoples knows how to solve the puzzle.

To see this, you must be moving quite slowly across the snow—imagine cross-country skiing or skinning gently uphill on a clear, blue-sky morning. It must have snowed recently, and the sun has to have been out. The phenomenon usually occurs in open patches of snow among stands of timber. If you look down at the base of pine trees when the conditions are right, you will see tiny specks of tree debris that seem to have moved of their own volition. They only move a few inches at most, but they leave a melted trail in the snow in spirals, loop de loops, or meanders like a river.

What makes them move? I don’t think it’s the wind, because the patterns are never alike, there can be hundreds under a tree, and each one goes its own way. Is the sun shining on the piece of debris and heating it, causing it to be drawn through the snow by molecular tension of water? Possibly, but there is more to it because the stuff moves in many directions and not always toward the sun.

I have presented this puzzle to snow scientists, avalanche forecasters, and countless groups of high school students in the winter backcountry. It seems wonderful to me that, in a world of information at our fingertips, riddles of nature remain. It’s for just this reason that I work as an outdoor educator. It certainly takes one’s mind off the uphills anyway.

If anyone can solve this mystery—or has any ideas on this whatsoever—please send me your thoughts. I’ll send a surprise gift to the person with the most plausible answer. Actually, I’ll describe the gift: It’s a DVD of the movie 2012 filmed in a theater in Nicaragua and dubbed into Spanish. Have a great ski season!

Currently there are "6 comments" on this Article:

  1. admin says:

    Crop circles?

  2. Cam Burns says:

    How wide are these spirals?

  3. The track itself is as wide as a small piece of debris from a pine tree, about 2 mil. The spirals are sometimes as large as 10 cm across.

  4. kurt says:

    nice question. I’ve noticed these too! I thought they looked like tracks from little bugs…

    But I like your explanation better: needles (or other debris) get hot in the sun. Hot needles melt snow. water floats needle. water surface tension makes needle move

    Here is where I maybe I have a new idea:

    needle moves to highest point of water (to the side… like a cork in a glass of water). If there were no other variables, the needle could go anywhere… Not necessarily towards the sun.

    The needle would tend to continue moving in one direction… because after settling on one side of the “glass” it would melt the snow there. It might turn because any infinite number of reasons… imperfections in the snow, wind, other debris, sun on one side of he needle… etc. This would explain random gradual turns.

    continuous gradual turns (like spirals) are harder to explain… shape of the needle? rotation of the earth?

    ha ha…


  5. andrew says:

    Wow, cool phenomenon. Seems like the needle will absorb enough radiation from the sun to cause melting and free water will form a large droplet connected to the debris due to the polarity/hydorphilic nature of it, etc. Then the water droplet/debris entity will flow to the area of snow with the lowest density/ largest pore space. The random looking track is probably due to the random nature in which snow is initially deposited. Sweet photo, Michael!

  6. steve says:

    Possibly, this is the same occurrence of a raised skin track on a micro scale. Winds swirl around randomly in trees, moving the heated particles over the fresh snow leaving a track. Then, just the slightest breeze creates the visible raised track of the object.

    I will keep my eyes peeled for this in the elk mountains.

    Sweet observation!

    Yeah for the BIG ONE!!!

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