Experimental evidence from both the atmosphere and the laboratory indicates that the presence of solutes can suppress the spontaneous ice nucleation rate in supercooled aqueous solution drops. We propose to study this phenomenon in the laboratory under atmospheric conditions, with complementary field and theoretical studies. The proposed laboratory measurements will be made in the University of Missouri Cloud Simulation Facility, using methods previously developed for ice nucleation studies in pure water drops. The solutes for the study will be derived from the CCN used to form the liquid drops. These aerosols will include both laboratory generated aerosols and those collected by aircraft from atmosphere. Ice crystal collections will be used for growth habit studies and air filter samples will be used for chemical analysis. Complementary aerosol deliquescence studies at low temperature will be made so that theoretical models can correctly treat the onset of the condensation process in a rising parcel of air.//
