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SUMMARY:Dynamical and microphysical processes controlling the persistence 
 of low level Arctic mixed-phase clouds - Dr Julien Savre (Geography\, Univ
 ersity of Cambridge)
DTSTART:20141124T141500Z
DTEND:20141124T151500Z
UID:TALK55114@talks.cam.ac.uk
CONTACT:Paul Griffiths
DESCRIPTION:Low level mixed-phase clouds in the Arctic\, that is boundary 
 layer clouds consisting of both ice crystals and liquid drops\, are often 
 found to persist during several days (especially in autumn) despite being 
 naturally unstable. As a matter of fact\, water saturation over ice occurr
 ing typically at temperatures lower than saturation over liquid water\, wh
 en both phases coexist in a single cloud\, the ice crystals have the tende
 ncy to grow at the expense of liquid droplets\, therefore removing all the
  liquid water until complete cloud glaciation.\nThe conditions required fo
 r mixed-phase clouds to persist over long periods of time involve complex 
 dynamical-microphysical interactions specific to the Arctic environment (l
 ow insulation\, weak surface fluxes\, specific aerosol composition...). Al
 though much has yet to be discovered\, I will try in this talk to describe
  some of the most important atmospheric phenomena playing a role in the pe
 rsistence of Arctic mixed-phase clouds. The results presented rely mostly 
 on small-scale/high-resolution numerical simulations of clouds observed du
 ring a measurement campaign which took place in northern Alaska in April 2
 008.
LOCATION:Unilever Lecture Theatre\, Department of Chemistry
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