Środowiskowe Seminarium Fizyki Atmosfery

The collection process of droplets by drops is an important process in precipitation formation and aerosol scavenging by rain especially from the point of view of cloud and climate models. For the last few decades, measurements of collision parameters have been based on measuring the mass growth rate, assuming constant droplet parameters, relative velocities of drop and droplets and evaporation conditions, and then inferring the collection efficiency in the integral. Digital in-line holography allows us to measure the collection efficiency directly, i.e. to measure the collision events themselves and their surrounding conditions simultaneously. To show proof of concept, an experiment was carried out in the Mainz vertical wind tunnel in a laminar flow with droplets and drop sizes corresponding to that observed in clouds using digital holographic particle tracking velocimetry. In the presentation I will describe the above method, the details of the experiment, the flow characterization and show the first collision statistics.