CCN activation of slightly soluble organics: the importance of small amounts of inorganic salt and particle phase

Abstract

Using a static thermal-gradient diffusion cloud condensation nucleus chamber we study the effect of small amounts ofinorganic salts on the cloud droplet activation of two slightly soluble organic aerosol components (adipic and succinicacid) and experimentally confirm the two maxima predicted by Kóhler theory modified to take limited solubility intoaccount. Equally importantly we suggest (and confirm experimentally) that solid and liquid (supersaturated) particles ofslightly soluble organic compounds follow two different Kóhler curves and that knowledge about the particle phase andthereby the humidity history is important for interpretation of experimental data and modelling of the aerosol indirectclimate effect.