Charging processes during the dissipation stage of thunderstorms
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ORIGINAL PAPER
Charging processes during the dissipation stage of thunderstorms V. Gopalakrishnan1 · S. D. Pawar1 · Manoj A. Domkawale1 Received: 24 July 2019 / Accepted: 22 July 2020 © Springer-Verlag GmbH Austria, part of Springer Nature 2020
Abstract Electric field and Maxwell current density measurements made below thunderstorms at Pune (India) have been analyzed to study the charging processes occurring during dissipation stage of thunderstorms. These observations suggest that during the dissipation stage of thunderstorm different charging processes contribute to the cloud electrification depending on the type of thunderstorms. Our observations suggest that updraft may not be sufficient to activate charging mechanism inside cloud during the dissipation stage in small thunderstorms. However, in big thunderstorms, non-inductive charging mechanism may be active during the dissipation stage. The recovery curves of electric field and Maxwell current density measured during dissipation stage of inverted polarity thunderstorms suggests that inductive charging mechanism may also contribute to the thunderstorm electrification.
1 Introduction The time variation of electric field at the Earth’s surface beneath a small thunderstorm generally follows a characteristic pattern during its lifetime. Typically, as a thundercloud becomes electrified, the buildup of negative charge in its lower portion causes the electric field at the ground to reverse its sign from the fair weather to foul weather polarity and rapidly increase in magnitude. When the magnitude of electric field reaches a few kilovolts per meter, there is an abrupt negative field change, usually occurring in less than one second due to neutralization of electric charge by lightning discharge. The electric field then recovers back, linearly or quasi-exponentially, to its pre-discharge value. Surface electric field and recovery curves of the electric field between two lightning discharges have often been used to study the electrification processes in thunderclouds (Wilson 1920; Wormell 1930; Illingworth 1971; Livingston and Krider 1978; Krider and Musser 1982; Deaver and Krider 1991). Illingworth (1971) observed that the recovery curves from close flashes are irregular and do not give useful information concerning the currents generating the dipole of the
Responsible Editor: Maja Telisman Prtenjak. * V. Gopalakrishnan [email protected] 1
Ministry of Earth Sciences, Indian Institute of Tropical Meteorology, Pune, India
thunderstorm can be derived from them. As the distance from the storm increases, then the recoveries become much more rapid and of reproducible shape. Krider and Musser (1982) observed that the rate of change of surface electric field remains constant between two lightning discharges even though the electric field, both at ground and aloft, undergoes large changes in amplitude and sometime even in polarity. These observations lead them to conclude that the charge generating processes operating in thunderclouds are field-independent. Pawar
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