Snow Ghosts & Rime Ice

Snow ghosts are very common at Whitefish Mountain. Snow ghosts aren't caused by snow "sticking" to the trees. Instead, snow ghosts are caused by the formation of rime ice on the tree. Rime ice is formed when super cooled water droplets that lack a nuclei (water droplets still in liquid form despite temperature being below freezing) attach themselves to anything not moving (such as a tree or lift tower). The tree or lift tower then acts as a nuclei for the super cooled water droplets, allowing the water droplets to freeze.

Due to the often heavy cloud cover and fog found in the mountains of Northwest Montana, and the Pacific Northwest in general, Rime Ice is a very common sight above 6000 feet. The lingering clouds/fog at the higher elevations allow Rime Ice to slowly build up on the trees, day after day, week after week. The weight of the rime ice, as the winter goes on and the Rime Ice continues to build (unless broken away by high winds or melting), can easily weigh thousands of pounds, breaking tree limbs and even snapping smaller trees over.

More practically speaking, skiing into a tree covered with Rime Ice isn't a pleasant sensation, either. Instead of skiing into a "fluffy tree", a skier instead is basically skiing into a flexible sheet of ice. And once disturbed, the "flexible sheet of ice" on the tree then begins to rain down parts of the ice into whatever crashed into it!

Finally, when Rime Ice forms in windy conditions, Rime Ice will "point" in the direction that the wind was blowing.

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