Evaluation of “Static” and “Dynamic” Seeding Concepts through Analyses of Israeli II and FACE-2 Experiments

Abstract

Abstract In static-mode seeding two assumptions are usually made: a deficiency in concentrations of natural ice crystals is the reason for delay, or even failure, of precipitation formation in certain cloud conditions; and, moderate increases in ice crystal concentrations, obtained by glaciogenic seeding of such clouds, will result in rainfall enhancement either by making the already existing process of rain formation more effective or by inducing precipitation formation in clouds that otherwise would not have precipitated naturally. The basic assumption behind seeding for dynamic effects is that increased cloud buoyancy, achieved through conversion of supercooled water to ice by seeding, will cause an increase in cloud depth, which in turn will result in stronger rainfall intensities, areas and durations. These basic assumptions are examined in terms of physical and statistical analyses of data from Israeli II (a static-mode seeding project) and FACE-2 (a dynamic-mode seeding project).