Banner Clouds

Beautiful bluebird conditions in the Wasatch this morning revealed a spectacular banner cloud downstream of Dromedary Peak.

Banner clouds typically form in upslope return flow on the lee side of a mountain peak, as illustrated below.  

Source: B. Geerts Lecture Notes

Professor Bart Geerts at the University of Wyoming provides more description of the process here.  Perhaps the most famous banner clouds in the world form downstream of the Matterhorn.

Source: Zacharie Grossen/Wikipedia Commons