Atmospheric Chemistry and Physics www.atmos-chem-phys.net 1680-7316 1680-7324 7 8 2007 10.5194/acp-7-2047-2007 http://www.atmos-chem-phys.net/7/2047/2007/ http://www.atmos-chem-phys.net/7/2047/2007/acp-7-2047-2007.html http://www.atmos-chem-phys.net/7/2047/2007/acp-7-2047-2007.pdf 2047 2055 2007-04-24 Definition of "banner clouds" based on time lapse movies J. H. Schween jschween@uni-koeln.de J. Kuettner D. Reinert J. Reuder V. Wirth currently at: Institute for Geophysics and Meteorology, University of Cologne, Germany National Center for Atmospheric Research, Boulder, CO, USA Institute for Atmospheric Physics, Johannes Gutenberg-University, Mainz, Germany Geophysical Institute, University of Bergen, Norway Banner clouds appear on the leeward side of a mountain and resemble a banner or a flag. This article provides a comprehensive definition of "banner clouds". It is based primarily on an extensive collection of time lapse movies, but previous attempts at an explanation of this phenomenon are also taken into account. The following ingredients are considered essential: the cloud must be attached to the mountain but not appear on the windward side; the cloud must originate from condensation of water vapour contained in the air (rather than consist of blowing snow); the cloud must be persistent; and the cloud must not be of convective nature. The definition is illustrated and discussed with the help of still images and time lapse movies taken at Mount Zugspitze in the Bavarian Alps. Banta, R.: The role of Mountain flows in making clouds, in: Atmospheric processes over complex terrain, edited by: Blumen, W., American Meteorological Society, Boston/Mass, pp. 229–283, 1990. Beer, T.: Atmospheric Waves, Adam Hilger Press, 1974. Benilov, E., S.: Does a sheared flow stabilize inversely stratified fluid?, Phys. Fluids, 14, 1674–1680, 2002. Douglas, C.: Some alpine cloud forms, Quart. J. Roy. Meteorol. Soc., 54, 175–178, 1928. Geerts, B.: The Origin of Banner Clouds: a Case of Scientific Amnesia ?, Bull. Austr. Meteorol. Ocean. Soc., 4, 6–9, 1992a. Geerts, B.: The origin of banner clouds: A potential vorticity perspective., in: Sixth Conference on Mountain Meteorology (Preprint Volume), edited by: Bean, J R., American Meteorological Society, http://www-das.uwyo.edu/~geerts/cwx/notes/chap08/banner.html, pp. 97–98, 1992b. Glickman, T S. (Ed.): Glossary of Meteorology, American Meteorology Society, Allen Press, second edn., http://amsglossary.allenpress.com/glossary, 2000. Grant, H D.: Cloud and Weather Atlas, Cowand-McCann, 1944. Hann, J.: Allgemeine Erdkunde, Gebrüder Stiepel, first edn., 1896. Hindman, E E. and Wick, E J.: Air Motions in the Vicinity of Mt. Everest as Deduced from Pilatus Porter Flights, Technical Soaring, XIV, 52–56, 1990. Houze, R., A.: Cloud dynamics, International geophysics series 53, Acad. Press, San Diego, 1993. Humphreys, W J.: Physics of the air, McGraw-Hill, first edn., 1920. Huschke, R E. (Ed.): Glossary of Meteorology, American Meteorology Society, Allen Press, first edn., 1959. Kirshbaum, D. J. and Durran, D. R.: Factors governing cellular convection in orographic precipitation, J. Atmos. Sci., 61, 682–698, 2004. Kuo, H., L.: Perturbations of plane Couette flow in stratified fluid and origin of cloud streets, Phys. Fluids, 6, 195–211, 1963. Küttner, J P.: Meteorologische Überraschungen für wettererfahrene Alpinisten, Die Alpen, XXV, 157–160, 1949. Küttner, J P.: Erinnerungen 1945–1948, in: Die Geschichte der Wetterstation Zugspitze; Geschichte der Meteorologie, edited by: Wege, K., Selbstverlag des Deutschen Wetterdienstes, Offenbach/Main, Vol 4, pp 70–75, 2000. Peppler, W.: Hinderniswolken am Säntisgipfel, Das Wetter, 44, 212–213, 1927. Scorer, R.: Clouds of the world, Stackpole Books, 1972. Smolarkiewicz, K. S. and Rotunno, R.: Low Froude number flow past three-diemsnsional obstacles. Part I: baroclinically generated lee vortices, J. Atmos. Sci., 46, 1154–1164, 1989. Whiteman, C. D.: Mountain Meteorology, Oxford University Press, 2000.