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Vaughan Phillips

Research in the Area of Clouds, Aerosols and Climate

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Multiple environmental influences on the lightning of cold-based continental cumulonimbus clouds. Part I : Description and validation of model

Author

  • Vaughan T.J. Phillips
  • Marco Formenton
  • Vijay P. Kanawade
  • Linus R. Karlsson
  • Sachin Patade
  • Jiming Sun
  • Christelle Barthe
  • Jean Pierre Pinty
  • Andrew G. Detwiler
  • Weitao Lyu
  • Sarah A. Tessendorf
Show all

Summary, in English

In this two-part paper, influences from environmental factors on lightning in a convective storm are assessed with a model. In Part I, an electrical component is described and applied in the Aerosol-Cloud model (AC). AC treats many types of secondary (e.g., breakup in ice-ice collisions, raindrop-freezing fragmentation, rime splintering) and primary (heterogeneous, homogeneous freezing) ice initiation. AC represents lightning flashes with a statistical treatment of branching from a fractal law constrained by video imagery. The storm simulated is from the Severe Thunderstorm Electrification and Precipitation Study (STEPS; 19/20 June 2000). The simulation was validated microphysically [e.g., ice/droplet concentrations and mean sizes, liquid water content (LWC), reflectivity, surface precipitation] and dynamically (e.g., ascent) in our 2017 paper. Predicted ice concentrations (;10 L21) agreed-to within a factor of about 2-with aircraft data at flight levels (2108 to 2158C). Here, electrical statistics of the same simulation are compared with observations. Flash rates (to within a factor of 2), triggering altitudes and polarity of flashes, and electric fields, all agree with the coincident STEPS observations. The ''normal'' tripole of charge structure observed during an electrical balloon sounding is reproduced by AC. It is related to reversal of polarity of noninductive charging in ice-ice collisions seen in laboratory experiments when temperature or LWC are varied. Positively charged graupel and negatively charged snow at most midlevels, charged away from the fastest updrafts, is predicted to cause the normal tripole. Total charge separated in the simulated storm is dominated by collisions involving secondary ice from fragmentation in graupel-snow collisions.

Department/s

  • Dept of Physical Geography and Ecosystem Science
  • MERGE: ModElling the Regional and Global Earth system

Publishing year

2020

Language

English

Pages

3999-4024

Publication/Series

Journals of the Atmospheric Sciences

Volume

77

Issue

12

Document type

Journal article

Publisher

Amer Meteorological Soc

Topic

  • Meteorology and Atmospheric Sciences

Keywords

  • Atmospheric electricity
  • CAPE
  • Cloud microphysics
  • Freezing precipitation
  • Ice crystals
  • Ice particles

Status

Published

ISBN/ISSN/Other

  • ISSN: 0022-4928