Determination of the size segregated chemical composition and on line size distribution measurement of aerosol during cloud formation

In order to observe changes in size distribution and chemical composition of aerosol particles during the formation of orographic clouds size segregated aerosol samples were collected at two sites of different altitudes in the west of the Vosges. Number size distributions covering a size range between 0.001 and 0.8 μm were monitored by means of a CNC - diffusion-battery-(CNC-DB) setup located at a site in the condensation level. During the condensation phase a growth of the small particles is observed. After the cloud event the aerosol does not recover it's original diameter. At the same time the mass of Sulfur in the aerosol in the small size range is elevated leading to a smaller Mass median diameter (MMD) of the Sulfur size distribution measured with a Berner impactor. The reason for this enrichment is an uptake of Sulfur from the gasphase during the cloud formation.