V. Lakshmana Rao, S.S.V.S. Rama Krishna and K.P.R. Vittal Murty
Abstract
Aerosols play an important role in cloud formation and subsequent precipitation. In the long run from climatological point of view, the gradual increase in aerosol content leads to a change in earth atmosphere, heat balance and radiation balance leading to global warming and subsequent climate change. In the present article the aerosol concentrations in the urban atmosphere is measured and reported. The rain water analysis was also made to find out the chemical nature of aerosols that are washed down due to precipitation in the monsoon season. It is interesting to note that the aerosols play crucial role not only in the formation of cloud clusters but also the subsequent precipitation, the precipitation washes down the pollutant aerosols and the aerosol concentration goes down, in that way it is a cyclic process: the aerosols help in cloud formation and precipitation, where as precipitation washes down the aerosols in the atmosphere, there is an optimum concentration of aerosols which will promote precipitation either less aerosols or excess of aerosols hamper the growth of clouds and the subsequent precipitation will be less or nil, thus the aerosols are important component in cloud physics and precipitation chemistry, the aerosols also absorb effectively the insulation or net radiation, many of the urban aerosols have strong absorption bands in the infrared region, so they will allow insulation to reach the earth surface but will strongly absorb the outgoing long wave radiation from the earth surface, so part of the radiation is trapped and re-radiated back leading to global warming. Such aerosols are known as green house aerosols.