On the formation of radiation fogs under heavily polluted conditions

H. Kokkola (1) , S. Romakkaniemi (1) , A. Laaksonen (1)

1 Department of Applied Physics [Kuopio]

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.

Domaines: Océan, Atmosphère

H. Kokkola, S. Romakkaniemi, A. Laaksonen. On the formation of radiation fogs under heavily polluted conditions. Atmospheric Chemistry and Physics, 2003, 3 (3), pp.581-589. ⟨hal-00295262⟩