Distribution of precipitation and wet deposition around an island mountainin south-west Poland

A comparison has been made between measurements of precipitation intensity and chemical composition and a three-dimensional model of airflow and orogr aphic rainfall enhancement. The 'seeder-feeder' effect is shown to be of im portance in rainfall distribution, wet deposition of pollutants and the mod ification of the chemical composition of rainfall over an isolated island m ountain. The results show increases in rainfall of between 30% and 83% over the hill, with the smallest increase corresponding to the presence of a st rong inversion layer. The peak rainfall enhancement occurred between 0.5 an d 2 lan downstream of the summit. The measured concentrations of major ions in the feeder-cloud droplets were greater than those in seeder rain by factors of between two and five. The scavenging of polluted cap cloud by rain drops resulted in an increase in w et-deposition rate by factors of between three and five, with the peak depo sition occurring approximately 2 lan downstream of the hill summit.