Chemical Interactions of Trace Atmospheric Constituents

Unlike the chemistry of simple mixtures of small numbers of reactants, the chemistry of the atmosphere involves complex interactions of large numbers of species. However, several key aspects of these interactions have been identified that account for major observable properties of the atmospheric chemical system. It is convenient to separate the description into gas phase and condensed phase interactions, not least because different chemical and physical processes are involved in these two cases. 

Condensed phase interactions can be divided roughly into two further categories chemical and physical. The latter involves all purely physical processes such as condensation of species of low volatility onto the surfaces of aerosol particles, adsorption, and absorption into liquid cloud and rainwater. Here, the interactions may be quite complex. For example, cloud droplets require a CCN, which in many instances is a particle of sulfate produced from SO2 and gas-particle conversion. If this particle is strongly acidic (as is often the case) HNO3 will not deposit on the aerosol particle rather, it will be dissolved in liquid water in clouds and rain. Thus, even though HNO3 is not very soluble in 

11a Release of CO from a variety of sources, mostly man-made. 

15 Isoprene and terpene oxidation to CO following reaction with OH. 

17 Release of N2O to atmosphere by variety of sources no significant sinks of N2O in the troposphere have been discovered stratospheric loss estimated by model calculations. 

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