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08:16
Ice Generation and the Heat and Mass Transfer Phenomena of Introducing Water to a Cold Bath of Brine
Published on: March 13, 2017
Solid ammonium sulfate aerosols as ice nuclei: a pathway for cirrus cloud formation
J P D Abbatt1, S Benz, D J Cziczo
1Department of Chemistry, University of Toronto, Toronto, ON M5S 3H6, Canada. jabbatt@chem.utoronto.ca
Science (New York, N.Y.)
|September 2, 2006
Summary
Solid ammonium sulfate aerosols facilitate cirrus cloud formation via heterogeneous ice nucleation. This pathway, influenced by agricultural ammonia emissions, impacts climate by altering cloud properties and radiative forcing.
Area of Science:
- Atmospheric Chemistry
- Cloud Physics
- Climate Science
Background:
- Cirrus clouds play a crucial role in Earth's radiative balance.
- The formation mechanisms of cirrus clouds, particularly continental cirrus, are not fully understood.
- Interhemispheric asymmetries in cloud onset suggest specific formation pathways.
Purpose of the Study:
- To investigate the role of solid ammonium sulfate aerosols in cirrus cloud formation.
- To determine if heterogeneous ice nucleation by these aerosols explains observed cirrus cloud properties.
- To assess the climate implications of this proposed cirrus formation pathway.
Main Methods:
- Laboratory measurements of ice nucleation on solid ammonium sulfate aerosols.
- Analysis of ice formation conditions (ice-saturation ratios).
- Incorporation of the mechanism into a climate model.
Main Results:
- Laboratory data support heterogeneous ice nucleation by solid ammonium sulfate aerosols.
- Ice formation occurs at low ice-saturation ratios, consistent with continental cirrus.
- Climate model simulations show this pathway generates fewer, larger ice crystals, reducing cloud albedo and longwave heating.
- The mechanism explains interhemispheric asymmetry in cloud onset.
Conclusions:
- Solid ammonium sulfate aerosols provide a significant source of ice nuclei for cirrus formation.
- This pathway links agricultural ammonia emissions to climate system changes.
- The mechanism impacts cirrus cloud radiative properties, influencing global climate.
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