Low-Pressure Electrical Discharge Experiment to Simulate High-Altitude Lightning Above Thunderclouds

Low-Pressure Electrical Discharge Experiment to Simulate High-Altitude Lightning Above Thunderclouds
Author: National Aeronautics and Space Adm Nasa
Publisher:
Total Pages: 34
Release: 2018-10-21
Genre:
ISBN: 9781729009475

Recently, extremely interesting high-altitude cloud-ionosphere electrical discharges, like lightning above thunderstorms, have been observed from NASA's space shuttle missions and during airborne and ground-based experiments. To understand these discharges, a new experiment was conceived to simulate a thundercloud in a vacuum chamber using a dielectric in particulate form into which electrodes were inserted to create charge centers analogous to those in an electrified cloud. To represent the ionosphere, a conducting medium (metallic plate) was introduced at the top of the chamber. It was found that for different pressures between approximately 1 and 300 mb, corresponding to various upper atmospheric altitudes, different discharges occurred above the simulated thundercloud, and these bore a remarkable similarity to the observed atmospheric phenomena. At pressures greater than 300 mb, these discharges were rare and only discharges within the simulated thundercloud were observed. Use of a particulate dielectric was critical for the successful simulation of the high-altitude lightning. Jarzembski, M. A. and Srivastava, V. Marshall Space Flight Center ...

Lightning

Lightning
Author: Vladimir A. Rakov
Publisher: Cambridge University Press
Total Pages: 734
Release: 2003-08-04
Genre: Science
ISBN: 9780521583275

Table of contents

The Lightning Discharge

The Lightning Discharge
Author: Martin A. Uman
Publisher: Academic Press
Total Pages: 391
Release: 1987-06-17
Genre: Science
ISBN: 0080959814

From the Preface: In the 18 years since my technical monograph Lightning (McGraw-Hill, 1969; Dover, 1984) was first published, there have been significant advances in our understanding of lightning, but, until now, there has been no new monograph on the subject. A number of edited collections of papers and conference proceedings relating to lightning have been published during this period and are listed in Appendix D as well as being referenced, where appropriate, throughout the text... In the present book, the chapters are organized primarily by lightning process. Each chapter contains a reference list of essentially all literature on the subject discussed in that chapter, although all of these references may not be cited in the text.

Spring Meeting

Spring Meeting
Author: American Geophysical Union. Meeting
Publisher:
Total Pages: 692
Release: 1996
Genre: Geophysics
ISBN:

"Sprites, Elves and Intense Lightning Discharges"

Author: Martin Füllekrug
Publisher: Springer Science & Business Media
Total Pages: 399
Release: 2006-05-27
Genre: Science
ISBN: 1402046294

Particularly intense lightning discharges can produce transient luminous events above thunderclouds, termed sprites, elves and jets. These short lived optical emissions in the mesosphere can reach from the tops of thunderclouds up to the ionosphere; they provide direct evidence of coupling from the lower atmosphere to the upper atmosphere. Sprites are arguably the most dramatic recent discovery in solar-terrestrial physics. Shortly after the first ground based video recordings of sprites, observations on board the Space Shuttle detected sprites and elves occurring all around the world. These reports led to detailed sprite observations in North America, South America, Australia, Japan, and Europe. Subsequently, sprites were detected from other space platforms such as the International Space Station and the ROCSAT satellite. During the past 15 years, more than 200 contributions on sprites have been published in the scientific literature to document this rapidly evolving new research area.

The Lightning Flash

The Lightning Flash
Author: Vernon Cooray
Publisher: IET
Total Pages: 600
Release: 2003
Genre: Technology & Engineering
ISBN: 0852967802

This unique book provides the reader with a thorough background in almost every aspect of lightning and its impact on electrical and electronic equipment. The contents range from basic discharge processes in air through transient electromagnetic field generation and interaction with overhead lines and underground cables, to lightning protection and testing techniques. This book is of value to anyone designing, installing or commissioning equipment which needs to be secured against lightning strikes, as well as being a sound introduction to research students working in the field.

Numerical Modeling of Leader Discharge Mechanisms in Lightning, Blue Jets, Gigantic Jets, and Sprites

Numerical Modeling of Leader Discharge Mechanisms in Lightning, Blue Jets, Gigantic Jets, and Sprites
Author: Caitano Da Silva
Publisher:
Total Pages:
Release: 2015
Genre:
ISBN:

The work presented in this dissertation is dedicated to the investigation of leader discharge mechanisms in lightning and transient luminous events. We introduce two new numerical models of the leader process that capture its onset and propagation, as briefly described below.The first theoretical model simulates air heating and streamer-to-leader transition in gas discharges. The model accounts for all physical processes known to play a role in the conversion of a streamer corona to a leader channel. Detailed discussion on the role of electron detachment in the development of the thermal-ionizational instability that triggers the spark development in short air gaps is presented. The dynamics of fast heating by quenching of excited electronic states is discussed and the scaling of its main channels with ambient air density is quantified. The developed model is employed to study the streamer-to-leader transition process and to obtain its scaling with ambient air density. The introduced methodology for estimation of leader speeds is based on the assumption that the propagation of a leader is limited by the air heating of every newly-formed leader section. It is demonstrated that the streamer-to-leader transition time has an inverse-squared dependence on the ambient air density at near-ground pressures, in agreement with similarity laws for Joule heating in a streamer channel. Model results indicate that a deviation from this similarity scaling occurs at very-low air densities, where the rate of electronic power deposition is balanced by the channel expansion, and air heating from quenching of excited electronic states is very inefficient. These findings place a limit on the maximum altitude at which a hot and highly-conducting lightning leader channel can be formed in the Earth's atmosphere. This result is important for understating of the gigantic jet discharges between thundercloud tops and the lower ionosphere. Our simulations of leader propagation at stratospheric altitudes demonstrate that initial speeds of gigantic jets are consistent with the leader propagation mechanism, and that the observed acceleration in gigantic jets can be attributed to the expansion of its streamer zone in a medium of exponentially-decreasing air density. This process defines the existence of an altitude at which the streamer zone becomes so long that it dynamically extends all the way to the ionosphere. We extend the air heating model to simulate the effects of strong currents flowing in sprites in the mesosphere. We show that fast air heating (due to quenching of excited electronic states) in sprite cores can produce >0.01 Pa pressure perturbations on the ground, observed in association with sprites. The second theoretical model simulates the electromagnetic radiation generated during the initial breakdown stage of lightning discharges. We use this model to describe in detail how the leader discharge dynamics generates the so-called initial breakdown pulses (IBPs) and narrow bipolar events (NBEs) observed with multi-station electric field change sensors on the ground. IBPs have been correlated with individual bursts of light that appear to be illuminations of a lightning leader channel; as a flash evolves the location of IBP sources inside the cloud coincides with the position of negative leaders as determined by a VHF lightning mapping system. NBEs are electric field signatures with broadband waveforms resembling classic IBPs in both amplitude and duration. Nonetheless, NBEs are quite peculiar in the sense that very infrequently they are followed by conventional lightning processes. Only a small fraction of positive-polarity NBEs happen as the first event in an otherwise regular intracloud lightning discharge. Typically, the initiator-type of NBEs has no difference with other NBEs that did not start lightning, except for the fact that they occur deeper inside the thunderstorm (i.e., at lower altitudes). In this dissertation we propose that IBPs and NBEs are the electromagnetic transients associated with the sudden (i.e., stepwise) elongation of the initial negative leader extremity in the thunderstorm electric field. To demonstrate our hypothesis we use a novel model of the leader electrodynamics. It consists of a generalization of electrostatic and transmission-line approximations existing in the refereed literature. We demonstrate how the IBP and NBE waveform characteristics directly reflect the properties of the bidirectional lightning leader (such as step length, for example) and amplitude of the thunderstorm electric field.

Electrical Processes in Atmospheres

Electrical Processes in Atmospheres
Author: H. Dolezalek
Publisher: Springer Science & Business Media
Total Pages: 875
Release: 2012-12-06
Genre: Science
ISBN: 3642852947

These Proceedings are published to give a full account of the Fifth International Conference on Atmospheric Electricity held in September 1974 in Garmisch-Partenkirchen in the Bavarian Alps in Germany. Traditionally, the Proceedings of these Conferences have served as reference books updating the textbooks and monographs on Atmospheric Electricity. As treated by these Conferences, Atmos pheric Electricity covers all aspects of this science, including the processes and problems which reach out into the Earth's environment as well as analogous processes on other planets and on the Moon. A history of these Conferences, an account of their purpose, and an outline of the scope and the preparation is to be found at the end of these Proceedings. There, also the Business Meetings of the involved organizations are mentioned. The Proceedings closely follow the original program and are accordingly organized into "Sessions". The papers printed in each "Session" in this book are the ones which were accepted for the sessions of the Conference with the same numbers and titles. Only the two "Special Sessions" have been given different numbers in the Proceedings, i.e. 2a and 10. In principle, all papers which were accepted by the Executive Panel either for full oral presentation or for printing in the Proceedings only, have in fact been included in these Proceedings, whether they were presented or not. In the latter case, a special note is made to explain the absence of a discussion.