On the formation of radiation fogs under heavily polluted conditions H. Kokkola, S. Romakkaniemi, and A. Laaksonen Department of Applied Physics, University of Kuopio, Finland
Abstract. We have studied the effect of gaseous pollutants on fog droplet growth
in heavily polluted air using a model that describes time-dependent sulfate production in the liquid phase and thermodynamical equilibrium between
the droplets and the gas phase. Our research indicates that the oxidation of
SO2 to sulfate has a significant effect on fog droplet growth especially when hygroscopic trace gases,
for example HNO3 and NH3 are present. The increased sulfate production by dissolution of hygroscopic
gases results from increased pH (caused by absorption of ammonia) and from the increased size of the fog/smog droplets. Our results
indicate that unactivated fogs may become optically very thick when the droplet concentrations are on the order of several thousand per
cubic centimeter of air.
Citation: Kokkola, H., Romakkaniemi, S., and Laaksonen, A.: On the formation of radiation fogs under heavily polluted conditions, Atmos. Chem. Phys., 3, 581-589, doi:10.5194/acp-3-581-2003, 2003.