Absorption of NH 3 and SO 2 during activation of atmospheric cloud condensation nuclei

Mark J Rood, R. M. Currie

Research output: Contribution to journalArticle


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 (NH 4 ) 2 SO 4 , H 2 SO 4 and H 2 O and are in equilibrium with gaseous SO 2 and NH 3 concentrations. The model incorporates liquid phase oxidation of S(IV) to S(VI) during adiabatic lifting of the CCN. Simultaneous absorption of SO 2 and NH 3 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 SO 2 and NH 3 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 SO 2 and NH 3 . 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


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

ASJC Scopus subject areas

  • Pollution

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