The cloud droplet size distribution is one of the key parameter for a quantitative microphysical description of clouds (e.g. Pruppacher and Klett, 1997). It plays an important role for the radiative characteristic of the cloud and is, for example needed to describe the anthropogenic influence (Gunn and Philips, 1957; Twomey, 1977) and the cloud lifetime effect (Albrecht, 1989; Rosenfeld and Lensky, 1998). Moreover, the knowledge of droplet size distribution is crucial for a better understanding of the onset of precipitation (Gunn and Philips, 1957; Stevens and Feingold, 2009) as well as the occult deposition input of clouds to vegetation, which is known to be a relevant component in the hydrological budget of tropical mountain cloud forests (Bruijnzeel et al., 2005; Eugster et al., 2006)

- J. K. Spiegel1, P. Zieger2, N. Bukowiecki2, E. Hammer2, E.Weingartner2, and W. Eugster1