Advances in Quantum Chemistry presents surveys of current developments in this rapidly developing field that falls between the historically established areas of mathematics, physics, chemistry, and biology. With invited reviews written by leading international researchers, each presenting new results, it provides a single vehicle for following progress in this interdisciplinary area. Theoretical methods have dramatically extended the reach and grasp of atmospheric scientists. This edition of Advances in Quantum Chemistry collects a broad range of articles that provide reports from the leading edge of this interaction. The chemical systems span the range from atoms to clusters to droplets. Electronic structure calculations are used to uncover the details of the breakdown and removal of emissions from the atmosphere and the simultaneous development of air pollution including ozone and particles. The anomalous enrichment of heavy isotopes in atmospheric ozone is discussed using RRKM theory, and a number of techniques are presented for calculating the effect of isotopic substitution on the absorption spectra of atmospheric molecules.