Connecting hygroscopic growth at high humidities to cloud activation for different particle types

H. Wex, F. Stratmann, T. Hennig, S. Hartmann, D. Niedermeier, E. Nilsson, R. Ocskay, D. Rose, I. Salma, M. Ziese

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This work recompiles studies that have been done with respect to hygroscopic growth in the regime of high relative humidities and with respect to activation for different kinds of particle at LACIS (Leipzig Aerosol Cloud Interaction Simulator) during the last few years. The particles examined consisted of a mixture of succinic acid and ammonium sulfate, seawater samples, soot coated with an organic and/or an inorganic substance, and two different atmospheric HULIS (HUmic LIke Substance) samples. An influence of changing non-ideal behavior and of slightly soluble substances on the hygroscopic growth was found in varying degrees in the subsaturation regime. The measured hygroscopic growth was extrapolated towards supersaturation, using a simple form of the Köhler equation, and assuming a constant number of molecules/ions in solution for high relative humidities (≥95% or ≥98%, depending on the particles). When the surface tension of water was used, the modeled critical supersaturations reproduced the measured ones for the seawater samples and for the coated soot particles. To reach agreement between measured and modeled critical supersaturations for the HULIS particles, a concentration-dependent surface tension had to be used, with values of the surface tension that were lower than that of water, but larger than those that had been reported for bulk measurements in the past.

Original languageEnglish
Article number035004
JournalEnvironmental Research Letters
Issue number3
Publication statusPublished - Jul 1 2008



  • Activation
  • Hygroscopic growth
  • Non-ideal behavior
  • Slight solubility
  • Surface tension

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment
  • Environmental Science(all)
  • Public Health, Environmental and Occupational Health

Cite this

Wex, H., Stratmann, F., Hennig, T., Hartmann, S., Niedermeier, D., Nilsson, E., Ocskay, R., Rose, D., Salma, I., & Ziese, M. (2008). Connecting hygroscopic growth at high humidities to cloud activation for different particle types. Environmental Research Letters, 3(3), [035004].