On the evaporation of ammonium sulfate solution
- Departments of aChemistry and
- cEarth and Planetary Science, University of California, Berkeley, CA 94720; and
- bChemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
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Edited by Mark H. Thiemens, University of California at San Diego, La Jolla, CA, and approved September 25, 2009 (received for review July 16, 2009)
Abstract
Aqueous evaporation and condensation kinetics are poorly understood, and uncertainties in their rates affect predictions of cloud behavior and therefore climate. We measured the cooling rate of 3 M ammonium sulfate droplets undergoing free evaporation via Raman thermometry. Analysis of the measurements yields a value of 0.58 ± 0.05 for the evaporation coefficient, identical to that previously determined for pure water. These results imply that subsaturated aqueous ammonium sulfate, which is the most abundant inorganic component of atmospheric aerosol, does not affect the vapor–liquid exchange mechanism for cloud droplets, despite reducing the saturation vapor pressure of water significantly.
Footnotes
- 1To whom correspondence should be addressed. E-mail: rccohen{at}berkeley.edu
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Author contributions: R.J.S. and R.C.C. designed research; W.S.D. performed research; W.S.D. analyzed data; and W.S.D. wrote the paper.
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The authors declare no conflict of interest.
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This article is a PNAS Direct Submission.
