The collection of fog droplets by a jet impaction stage

Abstract

Jet impaction stages are not commonly used for collecting wet aerosol particles from nearly saturated or slightly supersaturated atmospheres, and yet, with an adequate design, the advantages of jet impaction stages, i.e. a sharp effeciency curve and well determined volumetric flow rate, can be made available to fog collection techniques. The condensation of water from supersaturated vapours is unlikely to play an important role in jet impaction stages if the transit times of the supersaturated fluid are sufficiently short. Initial experiments performed at a field site near Bologna, Italy, in 1986 to determine the liquid water content of fogs, demonstrated that the temporal resolution is better than 0.5h and low liquid water contents of ∼ 0.01 g m-3 can be determined with confidence. © 1988.