Aerosol-cirrus interactions: A number based phenomenon at all? M. Seifert , J. Ström, R. Krejci , A. Minikin, A. Petzold, J.-F. Gayet, H. Schlager, H. Ziereis, U. Schumann, and J. Ovarlez Department of Meteorology, Stockholm University, Stockholm, Sweden Air Pollution Laboratory, Institute for Applied Environmental Research, Stockholm University, Stockholm, Sweden Deutsches Zentrum für Luftund ...