An Examination of Clouds at a Mountain-Top Site in Central Sweden: The Distribution of Solute within Cloud Droplets

Noone, K.J., Ogren, J.A. and Heintzenberg, J., 1990. An examination of clouds at a mountain-top site in central Sweden: the distribution of solute within cloud droplets. Atmos. Res., 25: 3-15. An experiment aimed at examining both the physical and chemical inhomogeneity in clouds was carried out during July-August 1986 at a mountain site in central Sweden. As part of the experiment, two counterflow virtual impactor (CVI) probes were used to sample cloud droplets. The CVI probes provided information regarding both the physical (i.e. liquid water, droplet number) and chemical (amount and partitioning of non-volatile material inside the cloud droplets) properties of the clouds at the site. The measurements showed that large fluctuations in liquid water content in one of the clouds studied were not reflected in large fluctuations in the partitioning of non-volatile material between droplets of two different size intervals. This indicates that processes that controlled the amount of liquid water in the cloud did not necessarily affect the distribution of material within the cloud droplets themselves in the same way. In another cloud, it was observed that the largest cloud droplets sampled had formed on the largest condensation nuclei, and the smallest cloud droplets sampled had formed on the smallest condensation nuclei.