Absorption of NH3 and SO2 during activation of atmospheric cloud condensation nuclei

M. J. Rood, R. M. Currie

Research output: Contribution to journalArticlepeer-review


A numerical model is presented that considers the micro-physics and chemistry of cloud condensation nuclei (CCN) as the nuclei are transported vertically from the base of a cloud. The CCN are initially composed of mixtures of (NH4)2SO4, H2SO4 and H2O and are in equilibrium with gaseous SO2 and NH3 concentrations. The model incorporates liquid phase oxidation of S(IV) to S(VI) during adiabatic lifting of the CCN. Simultaneous absorption of SO2 and NH3 between the cloud droplets and gaseous dispersion medium is also considered. The model also evaluates whether the droplets are in chemical equilibrium with respect to gaseous SO2 and NH3 concentrations. Results from the model indicate that oxidation of S(IV) increases cloud droplet acidity during activation of the CCN. Large cloud droplets also exhibit gas phase mass transfer limitations with respect to SO2 and NH3. pH values of the resulting cloud droplet size distribution range over 3 pH units within the cloud at typical atmospheric conditions.

Original languageEnglish (US)
Pages (from-to)2847-2854
Number of pages8
JournalAtmospheric Environment (1967)
Issue number12
StatePublished - 1989
Externally publishedYes


  • Aerosol
  • absorption
  • activation
  • ammonia
  • cloud condensation nucleus
  • cloud droplets
  • sulfur dioxide

ASJC Scopus subject areas

  • General Environmental Science
  • General Earth and Planetary Sciences


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