Broadening of cloud droplet size spectra by stochastic condensation: effects of mean updraft velocity and CCN activation.

Broadening of cloud droplet size spectra by stochastic condensation: effects of mean updraft... AbstractWe study the condensational growth of cloud droplets in homogeneous isotropic turbulence by means of a Large Eddy Simulation (LES) approach. We investigate the role of a mean updraft velocity and of the chemical composition of the cloud condensation nuclei (CCN) on droplet growth. The results show that a mean constant updraft velocity superimposed to a turbulent field reduces the broadening of the droplet size spectra induced by the turbulent fluctuations alone. Extending our previous results regarding stochastic condensation (Sardina et al. 2015), we introduce a new theoretical estimation of the droplet size spectrum broadening which accounts for this updraft velocity effect. A similar reduction of the spectra broadening is observed when the droplets reach their critical size, which depends on the chemical composition of CCN. The analysis of the square of the droplet radius distribution, proportional to the droplet surface, shows that for large particles the distribution is purely Gaussian, while it becomes strongly non-Gaussian for smaller particles, with the left tail characterized by a peak around the haze activation radius. This kind of distribution can significantly affect the later stages of the droplet growth involving turbulent collisions, since the collision probability kernel depends on the droplet size, implying the need for new specific closure models to capture this effect. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of the Atmospheric Sciences American Meteorological Society

Broadening of cloud droplet size spectra by stochastic condensation: effects of mean updraft velocity and CCN activation.

Loading next page...
 
/lp/ams/broadening-of-cloud-droplet-size-spectra-by-stochastic-condensation-gTn4cOoUhb
Publisher
American Meteorological Society
Copyright
Copyright © American Meteorological Society
ISSN
1520-0469
D.O.I.
10.1175/JAS-D-17-0241.1
Publisher site
See Article on Publisher Site

Abstract

AbstractWe study the condensational growth of cloud droplets in homogeneous isotropic turbulence by means of a Large Eddy Simulation (LES) approach. We investigate the role of a mean updraft velocity and of the chemical composition of the cloud condensation nuclei (CCN) on droplet growth. The results show that a mean constant updraft velocity superimposed to a turbulent field reduces the broadening of the droplet size spectra induced by the turbulent fluctuations alone. Extending our previous results regarding stochastic condensation (Sardina et al. 2015), we introduce a new theoretical estimation of the droplet size spectrum broadening which accounts for this updraft velocity effect. A similar reduction of the spectra broadening is observed when the droplets reach their critical size, which depends on the chemical composition of CCN. The analysis of the square of the droplet radius distribution, proportional to the droplet surface, shows that for large particles the distribution is purely Gaussian, while it becomes strongly non-Gaussian for smaller particles, with the left tail characterized by a peak around the haze activation radius. This kind of distribution can significantly affect the later stages of the droplet growth involving turbulent collisions, since the collision probability kernel depends on the droplet size, implying the need for new specific closure models to capture this effect.

Journal

Journal of the Atmospheric SciencesAmerican Meteorological Society

Published: Nov 27, 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 18 million articles from more than
15,000 peer-reviewed journals.

All for just $49/month

Explore the DeepDyve Library

Search

Query the DeepDyve database, plus search all of PubMed and Google Scholar seamlessly

Organize

Save any article or search result from DeepDyve, PubMed, and Google Scholar... all in one place.

Access

Get unlimited, online access to over 18 million full-text articles from more than 15,000 scientific journals.

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

DeepDyve

Freelancer

DeepDyve

Pro

Price

FREE

$49/month
$360/year

Save searches from
Google Scholar,
PubMed

Create lists to
organize your research

Export lists, citations

Read DeepDyve articles

Abstract access only

Unlimited access to over
18 million full-text articles

Print

20 pages / month

PDF Discount

20% off