Abstract: Sulphur dioxide is classified as very toxic for humans inhaled it. When it dissolved in cloud droplets or rain drops, a sulphurous acid forms. The acid rains formed on that way have a large impact on the environment by changing the soil, river and lakes composition. Therefore, clouds and precipitation influence tropospheric chemistry on several ways: cloud droplets provide an aqueous environment for aqueous–phase chemical reactions, wet deposition is an important sink for many tropospheric chemical species, and strong vertical motions in convective clouds (especially in Cumulonimbus) can transport species very fast from boundary layer to the free troposphere. The role of the convective clouds in transporting and vertically redistributing trace gases is very important and currently not accurately represented in the models of pollution transport. Some reasons for these uncertainties are reactivity of trace gases and complexity in microphysical processes that take place in the clouds. The most significant emitted quantities of sulphur dioxide in Serbia come from thermal power plants from the energy sector, the mineral industry, animal and plant products from the food sector and from the production and processing of metals. An emission of sulphur dioxide and other air pollutants makes a significant environmental problem, especially during cold part of year when meteorological conditions are favourable for air pollution. These conditions encompass anticyclones situations with frequent temperature inversions and heavy fogs (anticyclone, cold, humid weather type which is most frequent in urban core of Belgrade, Serbia). In the light of increased number of world population that lives in the cities, and theirs expressed vulnerability to air pollution health effects this represents important objective to study. To accomplish this, we used chemistry module with the aqueous chemistry that we have developed and coupled with a complex 3D non-hydrostatic atmospheric model. This was used to make 3D simulations of a deep convective cloud which crosses over the chimney of the thermal power plant and analysis how it affects the plume from the chimney. These simulations are state-of-the-art in including realistic topography, high spatial resolution, several aqueous phase chemical reactions, and tracking of solute concentrations in different hydrometeor types. On that way we are able to make the most detailed analysis of time–dependent partitioning of SO2 emitted from thermal power plant stack among the gas phase, different hydrometeors, and precipitation. The results from this research may encourage more ecological solutions, leading to short- and long-term air-quality improvements. The concentration of S(IV) in cloud water and rainwater is calculated by detailed mass transfer approach that does not require gas–liquid equilibrium as Henry’s law does. The oxidation of dissolved SO2 with hydrogen peroxide, which is considered the most effective oxidant in clouds, is taken into account as the most important chemical transformation in cloud water. The sulphates formed on that way is than scavenged by Brownian diffusion, inertial impaction with rain drops, hail, and snow. Microphysical transfers include processes of evaporation, autoconversion, accretion, deposition, riming, melting, and sublimation.

Keywords: Cumulonimbus cloud, sulphate uptake, sulphate emission, convective sulphate redistribution

Biography: Dragana Vujović is an associate professor of meteorology at the Department of Meteorology, Faculty of Physics at University of Belgrade, Serbia. She completed her M.Sc. thesis in dynamic meteorology about the 3-D model characteristics of a Cb cloud which moves along a valley, and Ph.D. in cloud physics: „The simulation of cloud characteristics by mesomodel with chemistry included”. Her ongoing scientific interest span the topics related to the convective clouds and weather phenomena related to them, the influence of convective clouds on the air quality, evaluation of the stability indices for the local thunderstorm forecasting, the effect of microphysical processes and mass transfer parameterization and ice retention on the scavenging and redistribution of chemical species in the atmosphere. Some of the topics she dealt with related to the environmental pollution were also short–term forecasting of air pollution index, the link between local air quality and the weather types and bulk precipitation chemistry.