Skip to content

Ice nucleation of ammonia gas exposed montmorillonite mineral dust particles

by a. Salam, U. Lohmann, G. Lesins
Atmospheric Chemistry and Physics Discussions ()
Get full text at journal


The ice nucleation characteristics of montmoril- lonite mineral dust aerosols with and without exposure to ammonia gas were measured at different atmospheric tem- peratures and relative humidities with a continuous flow dif- fusion chamber. The montmorillonite particles were exposed to pure (100%) and diluted ammonia gas (25 ppm) at room temperature in a stainless steel chamber. Therewas no signif- icant change in the mineral dust particle size distribution due to the ammonia gas exposure. 100% pure ammonia gas expo- sure enhanced the ice nucleating fraction of montmorillonite mineral dust particles 3 to 8 times at 90% relative humidity with respect to water (RHw) and 5 to 8 times at 100% RHw for 120 min exposure time compared to unexposed montmo- rillonite within our experimental conditions. The percent- ages of active ice nuclei were 2 to 8 times higher at 90% RHwand 2 to 7 times higher at 100%RHwin 25ppm ammo- nia exposed montmorillonite compared to unexposed mont- morillonite. All montmorillonite particles are more efficient as ice nuclei with increasing relative humidities and decreas- ing temperatures. The activation temperature of montmoril- lonite exposed to 100% pure ammonia was 15◦C higher than for unexposed montmorillonite particles at 90% RHw. In the 25ppm ammonia exposed montmorillonite experiments, the activation temperature was 10◦C warmer than unexposed montmorillonite at 90% RHw. Degassing does not reverse the ice nucleating ability of ammonia exposed montmoril- lonite mineral dust particles suggesting that the ammonia is chemically bound to themontmorillonite particle. This is the first experimental evidence that ammonia gas exposed mont- morillonite mineral dust particles can enhance its activation as ice nuclei and that the activation can occur at temperatures warmer than –10◦C where natural atmospheric ice nuclei are very scarce.

Cite this document (BETA)

Authors on Mendeley

Readership Statistics

21 Readers on Mendeley
by Discipline
48% Chemistry
24% Environmental Science
19% Earth and Planetary Sciences
by Academic Status
24% Student > Ph. D. Student
14% Lecturer
14% Student > Bachelor
by Country
5% Switzerland
5% United States

Sign up today - FREE

Mendeley saves you time finding and organizing research. Learn more

  • All your research in one place
  • Add and import papers easily
  • Access it anywhere, anytime

Start using Mendeley in seconds!

Sign up & Download

Already have an account? Sign in