Banner cloud

Banner cloud on the Matterhorn

Banner cloud on Untersberg, Berchtesgadener Land

As Banner cloud is called stationary clouds in Lee by steep mountain peaks or ridges. They give the impression that they are pinned to the mountain like a banner. The windward side of the mountain or ridge is free of clouds. For many years, until the end of the 20th century, there was no satisfactory scientific explanation for the phenomenon.

Recent simulations now suggest that the most likely cause is a forced uplift in the ascending branch of a lee vortex ( lee vortex hypothesis ).

Individual evidence

↑ ^a ^b V. Wirth: Orographische Bannerwolken: Systematic investigations into a fascinating natural phenomenon . In: Deutscher Wetterdienst (Ed.): Promet . No. 98 , 2016 ( dwd.de [PDF; 51.0 MB ]).

[wirth2016-1] V. Wirth: Orographische Bannerwolken: Systematic investigations into a fascinating natural phenomenon . In: Deutscher Wetterdienst (Ed.): Promet . No. 98 , 2016 ( dwd.de [PDF; 51.0 MB ]).