ABSTRACT

Variability in climate may occur due to natural internal processes within the climate system or due to variations in natural or anthropogenic external forcing. Greenhouse gases and aerosols affect the climate by altering the incoming solar radiation and outgoing infrared radiation. Change in the atmospheric abundance or properties of these gases and particles can result in a warming or cooling of the climate system. The sources of aerosols can be classified into primary and secondary. The annual production rates of major aerosol types produced from natural sources and anthropogenic activities exhibit significant variations. The major aerosol species present in the atmosphere include sea salt, mineral dust, sulfate, nitrate, and carbonaceous aerosols. Aerosols in the atmosphere are removed by a variety of dry and wet removal processes. The removal mechanisms are function of aerosol sizes, types, their residence times, and altitude.