Aerosol chamber study of optical constants and N2O5 uptake on supercooled H2SO4/H2O/HNO3 solution droplets at polar stratospheric cloud temperatures

The mechanism of the formation of supercooled ternary H2SO4/H2O/HNO3 solution droplets in the polar winter stratosphere is mimicked during a simulation experiment at a large coolable aerosol chamber. The results shows that the implementation of a mixing rule approach, that is calculating the refractive indices of ternary H2SO4/H2O and HNO3 solution droplets based on accurate reference data sets for the two binary H2SO4/H2O and HNO3/H2O systems, is justified.