A RELATIONSHIP BETWEEN LIQUID WATER-CONTENT AND CHEMICAL-COMPOSITION IN CLOUDS

In this paper we present two-year results from the Cloud Chemistry Mea surements Programme, carried out at Mt. Brocken/Harz (Germany) to asse ss the influence of cloud physical parameters on the chemical composit ion of clouds, There are large variations in the chemical composition of cloud water. We found that the liquid water content of clouds predo minantly determines the ionic content. The relationship is best approx imated by a power function, nearly identical for all chemical species. We identified deviations of data points from the general relationship accompanying events with different air pollution situations. An impor tant conclusion is that cloud chemistry monitoring in the sense of air pollution studies is meaningless without measurement of cloud physica l parameters, These are liquid water content, cloud base altitudes, an d to some extent, droplet size distribution.