Chinook Glacier Glow

A chinook-arch cloud hovers at sunset over Saint Mary Lake in Glacier National Park. The lower flanks of Red Eagle Mtn (right) and Curly Bear Mtn (left) bask in the glow of this unusual cloud formation that is only observed in a few locations globally.
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This is my favorite cloud formation, because it often creates stunning sunrises and sunsets. A Chinook arch is a band of stationary stratus clouds caused by air rippling over the mountains and usually forms on the lee (downsloping) side of a hill. They often indicate very high winds aloft and warm gusty winds at the surface.
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The name Chinook, is claimed by popular folklore to mean "ice-eater" wind, and was derived from the region it most commonly occurs, the interior of the Pacific Northwest. However, I have seen most commonly along Montana's Rocky Mountain Front, and similarly along Colorado's Front Range.