| description: |
Besides greenhouse gases, atmospheric aerosols are among the environmental factors most influenced by human activity. The generation of new particles (nucleation) from atmospheric trace gases and their growth are thermodynamically hindered by the surface energy. These processes can occur only due to specific physical properties of clusters and nanometer particles; ionization and electric forces play a significant role in these processes. Nucleation is one of the key factors in weather formation, since it generates condensation nuclei and thereby influences the microstructure and development of clouds. The classic nucleation theory uses thermodynamics and correctly describes the growth of sufficiently large particles (with sizes above 3 nm), when their surface energy can be properly calculated. The chemical kinetics of cluster ions is applied in the size range of 0.3-1 nm. The researchers involved in the project are experts in both theories, and are also equipped with necessary facilities for the experimental verification of the theories, thus having all prerequisites for integrating the kinetic and thermodynamic methods, which would be considerable progress in the nucleation theory. The goal of this project is to reveal the relationships between corresponding atmospheric processes, to understand better the physical mechanisms of the processes, and to simulate the processes numerically. This knowledge should refine the forecasting of the consequences of the chemical and radioactive pollution of the atmosphere. The results of the study will be applicable for the estimation of the climatic effect of atmospheric aerosols and ionization using numerical models. This project will further the co-operation between the University of Tartu and the University of Helsinki in aerosol research, and with the Estonian Environmental Research Centre in environmental monitoring. |