Theory of Deliquescence and Modified Köhler Curves

Abstract

The conventional Köhler theory, which describes the equilibrium sizes of hygroscopic aerosol particles in humid air, is modified by considering the solubility limitation so that the deliquescence and hysteresis processes can also be explained. A set of modified Köhler curves was constructed based on the modified theory. The deliquescence, dehydration, and spontaneous crystallization points (relative humidities) that are the characteristics of the aerosol particles can be identified on the modified Köhler curve diagram. These characteristic relative humidities were derived analytically. The relationships between the equilibrium (wet) size, dry size, and the corresponding solute concentration of ammonium sulfate particles were also established for various ambient relative humidities.