On the ice-nucleating potential of warm hydrometeors in mixed-phase clouds
The question as to whether or not the presence of warm hydrometeors in clouds may play a significant role in the nucleation of new ice particles has been debated for several decades. While the early works of Fukuta and Lee (1986) and Baker (1991) indicated that it might be irrelevant, the more recen...
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| Published in: | Atmospheric chemistry and physics Vol. 21; no. 1; pp. 561 - 575 |
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| Main Authors: | , , , , |
| Format: | Journal Article |
| Language: | English |
| Published: |
Katlenburg-Lindau
Copernicus GmbH
15-01-2021
Copernicus Publications |
| Subjects: | |
| Online Access: | Get full text |
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| Summary: | The question as to whether or not the presence of warm hydrometeors in clouds may
play a significant role in the nucleation of new ice particles has been debated
for several decades. While the early works of Fukuta and Lee (1986) and
Baker (1991) indicated that it might be irrelevant, the more recent
study of Prabhakaran et al. (2020) suggested otherwise. In this work, we
attempt to quantify the ice-nucleating potential using high-fidelity flow
simulation techniques around a single hydrometeor and use favorable considerations
to upscale the effects to a collective of ice particles in clouds. While we find that ice nucleation
may be significantly enhanced in the vicinity of a warm hydrometeor
and that the affected volume of air is much larger than previously estimated, it is
unlikely that this effect alone causes the rapid
enhancement of ice nucleation observed in some types of clouds, mainly due to the low
initial volumetric ice concentration. Furthermore, it is demonstrated that the excess nucleation
rate does not primarily depend on the rate at which cloud volume is sampled by the meteors'
wakes but is rather limited by the exposure time of ice-nucleating particles to the wake,
which is estimated to be of the order of few microseconds. It is suggested to further investigate
this phenomenon by tracking the trajectories of ice-nucleating particles in order to obtain
a parametrization which can be implemented into existing cloud models to investigate second-order effects
such as ice enhancement after the onset of glaciation. |
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| ISSN: | 1680-7324 1680-7316 1680-7324 |
| DOI: | 10.5194/acp-21-561-2021 |