This is common on glaciers and snowfields during the height of summer. The corner can be either acute or obtuse, and can face right or left. Dihedral is a synonym. A very short pitch is a move. An outside corner is even smaller.
Ceiling is a synonym.
Sierra Crest the divide that runs along the very top of the High Sierra, separating the Great Basin and the Pacific Ocean watersheds. Sierra wave a lenticular cloud. This is typically found in the couloirs of the High Sierra in autumn.