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Vaughan Phillips

Universitetslektor

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Multiple Environmental Influences on the Lightning of Cold-Based Continental Convection. Part II : Sensitivity Tests for Its Charge Structure and Land-Ocean Contrast

Författare

  • Vaughan T.J. Phillips
  • Sachin Patade

Summary, in English

In Part I, an electrification scheme was described and a simulation of an observed cold-based storm from the U.S. Great Plains was validated with electrical observations. Most charge in the storm was separated by rebounding collisions of secondary ice originating from prior graupel-snow collisions. In this Part II, sensitivity tests are performed with the control simulation (Part I) and influences from environmental factors (aerosols, temperature, moisture, and shear) on lightning are elucidated. Environmental factors [e.g., convective available potential energy (CAPE)] controlling updraft speed are salient. When ascent is reduced by 30% and 70%, flashes become 70% fewer and disappear, respectively; faster ascent promotes positive cloud-to-ground (1CGs) flashes. Since cloud base is too cold (1°C) for coalescence, cloud condensation nucleus aerosol concentrations do not influence the lightning appreciably. The electrical response to varying concentrations of active ice nuclei is limited by most ice particles being secondary and less sensitive-a natural "buffer."Imposing a maritime sounding suggests that the land-sea contrast in lightning for such storms is due to the vertical structure of environmental temperature and humidity. Weak CAPE, and both entrainment and condensate weight from a low cloud base, suppress ascent and charging. Maritime thermodynamic conditions reduce simulated flash rates by two orders of magnitude. Reducing aerosol loadings from continental to maritime only slightly reinforces this suppression. Last, a conceptual model is provided for how any simulated storm is either normal because graupel/hail is mostly positively charged or else is inverted/anomalous because graupel/hail is mostly negatively charged, with environmental factors controlling the charging. Impacts from microphysical processes, including three processes of secondary ice production, on lightning are analyzed.

Avdelning/ar

  • eSSENCE: The e-Science Collaboration
  • Institutionen för naturgeografi och ekosystemvetenskap
  • MERGE: ModElling the Regional and Global Earth system

Publiceringsår

2022-01

Språk

Engelska

Sidor

263-300

Publikation/Tidskrift/Serie

Journal of the Atmospheric Sciences

Volym

79

Issue

1

Dokumenttyp

Artikel i tidskrift

Förlag

Amer Meteorological Soc

Ämne

  • Meteorology and Atmospheric Sciences

Nyckelord

  • Ice crystals
  • Lightning
  • Precipitation

Status

Published

ISBN/ISSN/Övrigt

  • ISSN: 0022-4928