In-situ Measurements of Cloud Droplet Dynamics

We present an in-situ experiment investigating the dynamics of cloud droplets and its dependence on the turbulent flow properties. This dynamics plays a major role in the rate of growth of cloud particles by coalescence and the resulting precipitation rate. The experiment takes place at a mountain research station at an altitude of 2650m, and makes use of a movable platform that can travel with the mean wind velocity over a distance of 5m and at speeds of up to 7.5m/s. Moving with mean velocity enables us to follow individual cloud particles over longer intervals, thus improving the quality of the statistics. Simultaneous measurements of other variables such as droplet size distribution and humidity fluctuations are done in order to develop a complete picture of the microphysical conditions within clouds. Preliminary results will be presented and discussed.