Abstract
We present results from moist convection in a mixture of pressurized sulfur hexafluoride (liquid and vapor), and helium (gas) to model the wet and dry components of the Earth’s atmosphere. To allow for homogeneous nucleation, we operate the experiment close to critical conditions. We report on the nucleation of microdroplets in the wake of large cold liquid drops falling through the supersaturated atmosphere and show that the homogeneous nucleation is caused by isobaric cooling of the saturated sulfur hexafluoride vapor. Our results carry over to atmospheric clouds: falling hail and cold rain drops may enhance the heterogeneous nucleation of microdroplets in their wake under supersaturated atmospheric conditions. We also observed that under appropriate circumstances settling microdroplets form a rather stable horizontal cloud layer, which separates regions of super- and subcritical saturation.
- Received 29 May 2017
DOI:https://doi.org/10.1103/PhysRevLett.119.128701
© 2017 American Physical Society
Physics Subject Headings (PhySH)
Focus
Drops Falling in Clouds Make More Drops
Published 22 September 2017
Experiments with a simplified version of the atmosphere show that falling drops seed many smaller droplets in their wake.
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