Description

Short-lived broken thin whips of cloud, irregularly distributed, appearing to tumble and break in a turbulent way in the airflow over, and to the immediate lee of, steep mountain peaks during periods of strong mountain summit level winds. Applies mainly to Altocumulus and Stratocumulus, possibly Cirrocumulus, sometimes coincident with the Duplicatus variety. (Editor's note: Supercillium is a cloud feature proposed by the Cloud Appreciation Society and is not yet recognised by the World Meteorological Organization (WMO)).

Figure 1: Turbulent Altocumulus Supercillium over Khumbu Hilal, Nepal, 21 March 2019. © Micheal Kehl

Figure 2: Supercillium clouds over the Eastern Sierra Nevada, California, above Owens Valley. © Stephen Ingram, www.ingramphoto.com

Figure 3: Superciillium cloud over the Sangre de Christo near Santa Fe, New Mexico. © Marc Davey