Techniques for Examining Drop Size Spectra in Water Sprays and Clouds

摘要

Qualitative comparisons have been made of water drop sampling methods for sprays and clouds, employing slides coated with oil, gelatin and soot. Oil-wetted and soot coated slides have been compared quantitatively when exposed in nominally identical water sprays simulating natural clouds. When compared with gelatin and oil-wetted slides, soot slides are more convenient to prepare, expose and analyse, and records are permanent. Within the inherent limitations of all spray sampling methods, drop size distributions and mean drop sizes given by the oil and soot methods are in substantial agreement, provided that known sources of error of the oil-wetted method are allowed for. Soot slides appear to be capable of detecting ice particles in clouds; quantitative calibrations relating ice impingement impressions to crystal size are required. (Author)