Abstract
Airborne data are presented on the impact of cloud processing on the aerosol mass light-scattering efficiency. Themeasurements, on marine stratocumulus, suggest that cloud processing significantly enhanced the mass light-scatteringefficiency in three of the five cases analysed. Enhancements were of the order of 10% for air detraining from the clouddeck relative to non-detraining air. A diagnostic modelling analysis suggested that the observed enhancements wereconsistent with the previously proposed explanation of in-cloud sulfate production in the particle size range for efficientlight scattering.