Influence of Microphysical Variability on Stochastic Condensation in a Turbulent Laboratory Cloud

Influence of Microphysical Variability on Stochastic Condensation in a Turbulent Laboratory Cloud AbstractDiffusional growth of droplets by stochastic condensation and a resulting broadening of the size distribution has been considered as a mechanism for bridging the cloud droplet growth gap between condensation and collision-coalescence. Recent studies have shown that supersaturation fluctuations can lead to a broadening of the droplet size distribution at the condensational stage of droplet growth. However, most studies using stochastic models assume the phase relaxation time of a cloud parcel to be constant. In this paper we ask how do variability in droplet number concentration and radius influence the phase relaxation time? And what effect does it have on the droplet size distributions? To answer these questions, we created steady state cloud conditions in the laboratory and used digital inline holography to directly observe the variations in local number concentration and droplet size distribution and, thereby, the integral radius. We also extend the stochastic equations to account for fluctuations in integral radius and obtain new terms that are compared with the laboratory observations. We find that the variability in integral radius is primarily driven by variations in the droplet number concentration and not the droplet radius. This variability does not contribute significantly to the mean droplet growth rate, but contributes significantly to the rate of increase of the size distribution width. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of the Atmospheric Sciences American Meteorological Society

Influence of Microphysical Variability on Stochastic Condensation in a Turbulent Laboratory Cloud

Loading next page...
 
/lp/ams/influence-of-microphysical-variability-on-stochastic-condensation-in-a-otcEg9uYFM
Publisher
American Meteorological Society
Copyright
Copyright © American Meteorological Society
ISSN
1520-0469
D.O.I.
10.1175/JAS-D-17-0158.1
Publisher site
See Article on Publisher Site

Abstract

AbstractDiffusional growth of droplets by stochastic condensation and a resulting broadening of the size distribution has been considered as a mechanism for bridging the cloud droplet growth gap between condensation and collision-coalescence. Recent studies have shown that supersaturation fluctuations can lead to a broadening of the droplet size distribution at the condensational stage of droplet growth. However, most studies using stochastic models assume the phase relaxation time of a cloud parcel to be constant. In this paper we ask how do variability in droplet number concentration and radius influence the phase relaxation time? And what effect does it have on the droplet size distributions? To answer these questions, we created steady state cloud conditions in the laboratory and used digital inline holography to directly observe the variations in local number concentration and droplet size distribution and, thereby, the integral radius. We also extend the stochastic equations to account for fluctuations in integral radius and obtain new terms that are compared with the laboratory observations. We find that the variability in integral radius is primarily driven by variations in the droplet number concentration and not the droplet radius. This variability does not contribute significantly to the mean droplet growth rate, but contributes significantly to the rate of increase of the size distribution width.

Journal

Journal of the Atmospheric SciencesAmerican Meteorological Society

Published: Nov 9, 2017

References

You’re reading a free preview. Subscribe to read the entire article.


DeepDyve is your
personal research library

It’s your single place to instantly
discover and read the research
that matters to you.

Enjoy affordable access to
over 12 million articles from more than
10,000 peer-reviewed journals.

All for just $49/month

Explore the DeepDyve Library

Unlimited reading

Read as many articles as you need. Full articles with original layout, charts and figures. Read online, from anywhere.

Stay up to date

Keep up with your field with Personalized Recommendations and Follow Journals to get automatic updates.

Organize your research

It’s easy to organize your research with our built-in tools.

Your journals are on DeepDyve

Read from thousands of the leading scholarly journals from SpringerNature, Elsevier, Wiley-Blackwell, Oxford University Press and more.

All the latest content is available, no embargo periods.

See the journals in your area

Monthly Plan

  • Read unlimited articles
  • Personalized recommendations
  • No expiration
  • Print 20 pages per month
  • 20% off on PDF purchases
  • Organize your research
  • Get updates on your journals and topic searches

$49/month

Start Free Trial

14-day Free Trial

Best Deal — 39% off

Annual Plan

  • All the features of the Professional Plan, but for 39% off!
  • Billed annually
  • No expiration
  • For the normal price of 10 articles elsewhere, you get one full year of unlimited access to articles.

$588

$360/year

billed annually
Start Free Trial

14-day Free Trial