ABSTRACT
This chapter addresses aerosol-cloud interactions, the couplings between aerosols and the climate system including biogeochemical cycles, aerosol deposition on snow, and geoengineering issues. The concentration, size, and composition of aerosols that can act as cloud condensation nuclei determine the cloud properties, evolution, and development of precipitation. Knowledge on how the sources of dust, its transport, deposition, and solubility will change in the future under the changing climate and anthropogenic activities is key to understanding the biogeochemical cycling of aerosols. Aerosol particles in the presence of supersaturation of water vapor grow to become cloud droplets through activation, and become cloud condensation nuclei. Cloud droplets are produced in the lower atmosphere by condensation of water on existing aerosol particles. The semi-direct effect occurs due to the absorbing aerosols in the atmosphere which absorb the radiation, heat the air mass surrounding it because of which cloud droplets evaporate.
