Vaughan Phillips
Research in the Area of Clouds, Aerosols and Climate
Effect of Aerosols on Freezing Drops, Hail, and Precipitation in a Midlatitude Storm
Author
Summary, in English
A midlatitude hail storm was simulated using a new version of the spectral bin microphysics Hebrew University Cloud Model (HUCM) with a detailed description of time-dependent melting and freezing. In addition to size distributions of drops, plate-, columnar-, and branch-type ice crystals, snow, graupel, and hail, new distributions for freezing drops as well as for liquid water mass within precipitating ice particles were implemented to describe time-dependent freezing and wet growth of hail, graupel, and freezing drops.Simulations carried out using different aerosol loadings show that an increase in aerosol loading leads to a decrease in the total mass of hail but also to a substantial increase in the maximum size of hailstones. Cumulative rain strongly increases with an increase in aerosol concentration from 100 to about 1000 cm(-3). At higher cloud condensation nuclei (CCN) concentrations, the sensitivity of hailstones' size and surface precipitation to aerosols decreases. The physical mechanism of these effects was analyzed. It was shown that the change in aerosol concentration leads to a change in the major mechanisms of hail formation and growth. The main effect of the increase in the aerosol concentration is the increase in the supercooled cloud water content. Accordingly, at high aerosol concentration, the hail grows largely by accretion of cloud droplets in the course of recycling in the cloud updraft zone. The main mechanism of hail formation in the case of low aerosol concentration is freezing of raindrops.
Department/s
- Dept of Physical Geography and Ecosystem Science
- MERGE: ModElling the Regional and Global Earth system
Publishing year
2016
Language
English
Pages
109-144
Publication/Series
Journal of Atmospheric Sciences
Volume
73
Issue
1
Document type
Journal article
Publisher
Amer Meteorological Soc
Topic
- Meteorology and Atmospheric Sciences
Status
Published
ISBN/ISSN/Other
- ISSN: 1520-0469