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Observations of two sprite‐producing storms in Colorado
Author(s) -
Lang Timothy J.,
Lyons Walter A.,
Cummer Steven A.,
Fuchs Brody R.,
Dolan Brenda,
Rutledge Steven A.,
Krehbiel Paul,
Rison William,
Stanley Mark,
Ashcraft Thomas
Publication year - 2016
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1002/2016jd025299
Subject(s) - sprite (computer graphics) , thunderstorm , storm , meteorology , geology , lightning detection , ionosphere , mesoscale convective system , advection , convective storm detection , atmospheric sciences , convection , convective available potential energy , doppler radar , geophysics , physics , doppler effect , astronomy , computer science , computer vision , thermodynamics
Two sprite‐producing thunderstorms were observed on 8 and 25 June 2012 in northeastern Colorado by a combination of low‐light cameras, a lightning mapping array, polarimetric and Doppler radars, the National Lightning Detection Network, and charge moment change measurements. The 8 June event evolved from a tornadic hailstorm to a larger multicellular system that produced 21 observed positive sprites in 2 h. The majority of sprites occurred during a lull in convective strength, as measured by total flash rate, flash energy, and radar echo volume. Mean flash area spiked multiple times during this period; however, total flash rates still exceeded 60 min −1 , and portions of the storm featured a complex anomalous charge structure, with midlevel positive charge near −20°C. The storm produced predominantly positive cloud‐to‐ground lightning. All sprite‐parent flashes occurred on the northeastern flank of the storm, where strong westerly upper level flow was consistent with advection of charged precipitation away from convection, providing a pathway for stratiform lightning. The 25 June event was another multicellular hailstorm with an anomalous charge structure that produced 26 positive sprites in less than 1 h. The sprites again occurred during a convective lull, with relatively weaker reflectivity and lower total flash rate but relatively larger mean flash area. However, all sprite parents occurred in or near convection and tapped charge layers in adjacent anvil cloud. The results demonstrate the sprite production by convective ground strokes in anomalously charged storms and also indicate that sprite production and convective vigor are inversely related in mature storms.