My brother and I took a quick trip up to the top of Berthoud Pass to take some photographs of snow cornices earlier this week.
According to Merriam-Webster Dictionary, a cornice is “the decorative top edge of a building or column”. A secondary definition, though, is “an overhanging mass of windblown snow or ice usually on a ridge“.
Cornices are made when winds reaching speeds of over a hundred miles an hour pick up snow and carries it to the edge of a cliff. When the howling winds cross the cliff edge, it puts the “pack” in “snowpack”, pounding the snow into a ledge of concrete-hardness. The snow builds up on the ever-lengthening ledge and, by spring, has formed a frozen white wave on the mountain top.
The area bare of snow has a much different ecosystem than the one just to windward of it. The bare area has to endure screaming winds, sub-zero temperatures and little moisture. Under the cornice, it is comparatively warm, wet and still.
Amy Law, Science Geek 