Aerosol scavenging by ice in supercooled clouds

An experimental study of aerosol scavenging by ice in supercooled clouds was conducted with the help of a uniquely designed cloud chamber facility. Techniques for detecting the submicron particles scavenged by individual ice crystals were developed.;The effects of microphysical parameters in the scavenging process were examined quantitatively. Data of both the aerosol scavenging rates and the growth of ice crystals were documented as functions of cloud temperature, liquid water content, and the sizes of aerosol particles and ice crystals. Scavenging data were acquired at temperatures of ;The scavenging data were found to agree with most of the previously published theoretical results and experimental data. The liquid water content was found to have effects on both the aerosol scavenging and the growth of the ice crystals. Under supercooled cloud conditions, the cloud droplets may enhance the vapor deposition in the growth of ice crystals. Despite the liquid-water enhancements in the crystal growth, it was found that the scavenging in supercooled clouds was reduced because thermophoresis was enhanced due to the additional surface warming from the enhanced vapor deposition.;The maximum scavenging kernel for ice crystals appears at ;The data clarify the theories of scavenging mechanisms and substantiate some current theoretical models. Therefore, the theoretical models may be adapted to evaluate aerosol scavenging by ice in atmospheric supercooled clouds.