Atmos. Chem. Phys. Discuss., 3, 389-411, 2003
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On the formation of radiation fogs under heavily polluted conditions
H. Kokkola, S. Romakkaniemi, and A Laaksonen
1Department 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 andNH3 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. As a result of the enhancement of the droplet growth the optical thickness of the fog will increase.

Citation: Kokkola, H., Romakkaniemi, S., and Laaksonen, A: On the formation of radiation fogs under heavily polluted conditions, Atmos. Chem. Phys. Discuss., 3, 389-411, doi:10.5194/acpd-3-389-2003, 2003.
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