Applicability of the VisiSize D30 shadowgraph system for cloud microphysical measurements

Abstract. A commercial shadowgraph system, the Oxford Lasers VisiSize D30, originally designed to characterize industrial and agricultural sprays, was tested with respect its application for measuring cloud microphysical properties such as droplet size distribution number concentration. laboratory experiment a dense stream of polydisperse cloud-like droplets indicated strong dependence depth field, thus also sample volume, on particle size. This relationship determined suitable correction method developed improve estimations concentration distribution. The spatial homogeneity detection probability inside volume minimum diameter providing uniform were examined. second monodisperse produced by Flow Focusing Monodisperse Aerosol Generator (FMAG) verified sizing accuracy demonstrated reasonable agreement between instruments. Effects collisions evaporation FMAG observed. Finally, when instrument applied atmospheric clouds at mountain-based observatory, it performed reliably during 3-week-long field experiment. Based tests, recommendations concerning use measurements formulated.