Humidity Required for Ice Nucleation from the Vapor onto Silver Iodide and Lead Iodide Aerosols over the Temperature Range −6 to −67°C

Abstract

The ice saturation ratio at which 1% of aged silver iodide and lead iodide aerosol particles nucleate ice from moist air is observed to depend on temperature. Between roughly ?30 and ?67°C the threshold for both aerosol types rises slowly with decreasing temperature in agreement with a simple classical nucleation theory. Between ?6 and ?30°C the threshold for the silver iodide aerosol rises more rapidly than predicted by simple theory while the threshold for lead iodide decreases.