A mechanism for hydrochloric acid production in cloud

Abstract

A theoretical model describing the general interaction between atmospheric trace gases, such as SO₂, NH₃, CO₂ and O₂, chemical reactant gaseous product H₂SO₄ and hydrometeors containing NaCl is proposed to study a possible mechanism for hydrochloric acid production in non-precipitating cloud and the determination of the pH value of cloud droplets. Four different cloud droplet distributions have been used to estimate the upper limit of the amount of gaseous HCl released into the atmosphere resulting from the evaporation of cloud droplets. It is shown that the acid production and the amount of HCl released depend on the following factors: (a) the temperature of the cloud; (b) the oxidation rates; (c) the ambient concentration of SO₂, NH₃, and H₂SO₄; (d) the life cycle of the cloud; and (e) the liquid water content of the cloud. This proposed chemical model also predicts a pH value spectrum depending on the cloud droplet distribution. Field measurements for the dependence of pH value on particle size and spatial distribution of gaseous HCl are recommended.

Parent Publication

• Proceedings of the first international symposium on acid precipitation and the forest ecosystem

Citation

Yue, Glenn K.; Mohnen, Volkar A.; Kiang, C. S. 1976. A mechanism for hydrochloric acid production in cloud. In: Dochinger, L. S.; Seliga, T. A., eds. Proceedings of the first international symposium on acid precipitation and the forest ecosystem; Gen. Tech. Rep. NE-23. Upper Darby, PA: U.S. Department of Agriculture, Forest Service, Northeastern Forest Experiment Station. 181-203