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Published 1986 | public
Book Section - Chapter

The Chemistry and Physics of Acid Fogs, Clouds and Haze Aerosol


The chemistry of fogs, clouds, dew and rain at selected locations in California bas been observed over the last several years. Fog and cloud water in southern California often has extremely low pH values (i.e., 1.7 ≤ pH ≤ 4) and extremely high concentrations of sulfate, nitrate, ammonium ion and trace metals. A representative set of values reported by Waldman et al and Munger et al are given in Table I along with values reported for other sites around the world. Of special interest are the high values observed for SO_4^(2-), NO_3-, S(IV), CH_2O, Fe, Mn, Pb and Cu in fog water. These values and their time-dependent changes as shown in Figures 1 and 2 indicate that fogs provide a very reactive environment for the accumulation of HNO_3 and H_25O_4. Concomitant incorporation of NH_3 gas and calcareous dust into the droplet phase neutralizes some of the acidity.

Additional Information

© 1986 Lewis Publishers. We are grateful to the California Air Resources Board, the National Center for Atmospheric Research, and the U.S. Environmental Protection Agency for their support of the research described above. In particular we would like to thank Dr. J. Calvert, Dr. M. Dodge, Dr. J. Holmes, Dr. D. Lawson, Dr. R. Papetti and Mr. E. Fujita for their assistance in making this research possible.

Additional details

August 19, 2023
October 23, 2023