Chemistry of aerosols, cloud droplets, and rain in the Puerto Rican marine atmosphere

Abstract

The chemical changes occurring during the transformation of aerosols to cloud droplets and rain were observed in orographic clouds on the eastern end of the island of Puerto Rico. Comparisons of elemental ratios in particles and rain and of elemental particle size distributions in and out of the clouds demonstrated scavenging efficiencies of >100% for the elements I, Br, and Cl relative to Na and of <25% for the elements Al, Mn, and V relative to Na. These different scavenging efficiencies are consistent with predictions based on existing cloud physics theory and are a reflection of the geochemical properties of the aerosol consisting partly of a hygroscopic sea salt component containing I, Br, Cl, and Na and partly of a soil dust component containing Al, Mn, and possibly V.