Ice nucleation in the wake of warm hydrometeors
Abstract
The formation of ice in mixed-phase clouds greatly impacts Earth's hydrologic cycle. The intensity, distribution and frequency of precipitation as well as radiative properties of clouds in the mid-latitudes are strongly influenced by the number concentration of ice particles. A long-standing riddle in mixed- phase clouds is the frequent observation of measured ice particle concentrations several orders of magnitude higher than measured ice-nucleating particle concentrations. Here, we report laboratory observations of copious cloud droplets and ice crystals formed in the wake of a warm, falling water drop. We show here that water droplets and ice particles form in the wake of a falling hot water drop, which is a laboratory surrogate for a relatively warm hydrometeor (graupel or hail) in a cloud growing by accretion of super-cooled cloud droplets. Aerosols were activated in the transient regions of very high supersaturation due to evaporative mixing (mixing of the warm water vapor from the drop with the cold ambient air) in the wake of the drop. We extend these results to typical mixed-phase atmospheric conditions, and our calculations show that the induced evaporative supersaturation may significantly enhance the activated ice nuclei concentration in the particle's wake.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.A53O3114P
- Keywords:
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- 0305 Aerosols and particles;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 0320 Cloud physics and chemistry;
- ATMOSPHERIC COMPOSITION AND STRUCTURE;
- 3311 Clouds and aerosols;
- ATMOSPHERIC PROCESSES