Particle production near marine clouds: Sulfuric acid and predictions fromclassical binary nucleation

Recent experiments demonstrate that cloud processes in the free troposphere , and at times in the marine boundary layer (MBL), can result in the produc tion of new aerosol particles linked to sulfuric acid production that is ph otochemically driven. Here we provide observational evidence from the tropi cs and mid-latitudes indicating that this nucleation is often in accord wit h predictions of classical binary nucleation theory when it is applied to t he high humidity environment near evaporating clouds edges located above th e MEL. Coupled with suitable models for the relevant chemical species and c onditions, these observations suggest a means for modeling natural particle production in these regions.