CHEM 302 Chapter 8: Chapter 8.pdf
Document Summary
Aerosols in the atmosphere have several important environmental effects. the high concentrations found in urban environments. They scatter and absorb visible radiation, limiting visibility. They affect the earth"s climate both directly (by scattering and absorbing radiation) and indirectly (by serving as nuclei for cloud formation). They provide sites for surface chemistry and condensed-phase chemistry to take place in the atmosphere. We present in this chapter a general description of the processes controlling aerosol abundances and go on to discuss radiative effects in more detail. Chemical effects will be discussed in subsequent chapters. Atmospheric aerosols originate from the condensation of gases and from the action of the wind on the earth"s surface. Fine aerosol particles (less than 1 m m in radius) originate almost exclusively from condensation of precursor gases. A typical chemical composition for fine aerosol in the lower troposphere is shown in.