The objective of this project is to study heterogeneous (multiphase) reactions of SO2 and NO2 in laboratory-generated clouds. Specific questions to be addressed in the proposed research are: What is the role of water phase change (form vapor to condensed cloud drops) in scavenging and oxidation of SO2 in the presence of ammonia and other atmospheric gases? What is the effect of water phase change on NO2 scavenging and chemical transformation? What is the effect of different cloud condensation nuclei (including those produced by combustion) on these processes? The approach to answering these questions involves the use of the LBL cloud chamber. Such an approach is advantageous because chemical and physical processes that occur in a system with dispersed water drops may be significantly different from those proceeding in a bulk system. These differences are related to the uptake of gaseous species into drops and the effects of chemical and physical properties of cloud condensation nuclei on liquid water composition, drop concentration, and size distribution.
