Changes in aerosol size- and phase distributions due to physical and chemical processes in fog

Measurements of the scavenging efficiency of aerosol particles in fog are presented. The scavenging efficiency as a function of size for accumulation-mode particles is presented, along with efficiencies for the total number, accumulation-mode number, and accumulation-mode volume. Particles below ca. 0.3 μm diameter were not efficiently scavenged in the fogs. The scavenging efficiency for accumulation-mode particles showed two steps, indicating that the hygroscopic/hydrophobic nature of the aerosol appeared to have been a controlling factor in determining scavenging efficiencies. Observed changes in the aerosol size distributions are discussed in reference to the processes (i.e., in-cloud scavenging, aqueous-phase reactions) potentially influencing them.