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With around 2000 thunderstorms active on the planet's surface at any given time, lightning is one of Earth's more prevalent natural phenomena. Each lightning return stroke radiates a wideband electromagnetic pulse (EMP), and it has long been known that fields radiated by lightning return strokes have far-reaching effects. In the Earth-ionosphere waveguide, lightning-radiated fields can propagate efficiently to great distances, being detectable at ranges in excess of several thousands of kilometers. Additionally, they can propagate through the magnetized plasma of the ionosphere and enter the magnetosphere as whistler-mode waves where they can interact with geomagnetically trapped charged particles in the Earth's radiation belts. In 1989, an entirely new class of lightning return stroke field effects was discovered in the form of large and brilliant but brief lightning-associated optical flashes in the upper atmosphere, collectively known as transient luminous events (TLEs). Elves, the most abundant kind of TLE, are rapidly expanding rings of light produced by lightning EMP-heating of the lower ionosphere. Centered above their parent lightning return strokes at 85--90 km altitudes, elves can expand to diameters of several hundreds of kilometers on sub-millisecond timescales. However, their very short lifetimes make elves difficult to observe, and most in-the-field studies of elves have featured instruments requiring manual triggering that allow for detailed study of captured events but necessarily involve high rates of missed detections. In this work, we present three years of elve observations made by a new free-running (non-triggered), ground-based, high-speed photometric imaging instrument called PIPER. This instrument is unique among ground-based instruments in that it does not require triggering and can observe nearly all elve activity within its field of view as it tracks a storm across the horizon over its several-hour lifetime. PIPER is a multi-wavelength, 64-anode photometer array composed of two horizontally-oriented and two vertically-oriented 16-anode photometer arrays. With a sampling rate of 25 kHz, the array provides ample time-resolution for resolving elves and adequate spatial resolution for discriminating elves from other transient optical phenomena (sprites, cloud flashes, meteors, etc.). We develop an algebraic technique for reconstructing the geometry of a particular elve from its photometric array observation. We then present aggregate observations of elves from four different multi-week summer observation campaigns and investigate many features of bulk elve activity that have not hitherto been possible to investigate with previous data sets. These features include peak storm-time elve production rates, the storm-to-storm and within-storm variability in elve production rates, elve production probability dependence on lightning return stroke parameters and local time of night, and distributions of elve geometric parameters. We also present observations of an unusual (and very infrequently reported) category of elves we call "elve doublets" and interpret their causative mechanism in terms of the EMP radiated from compact intracloud discharges.
Advances in Space Environment Research - Volume I contains the proceedings of two international workshops, the World Space Environment Forum (WSEF2002) and the High Performance Computing in Space Environment Research (HPC2002), organized by the World Institute for Space Environment Research (WISER) from 22 July to 2 August 2002 in Adelaide, Australia. The articles in this volume review the state-of-the-art of the theoretical, computational and observational studies of the physical processes of Sun-Earth connections and Space Environment. They cover six topical areas: Sun/Heliosphere, Magnetosphere/Bow Shock, Ionosphere/Atmosphere, Space Weather/Space Climate, Space Plasma Physics/Astrophysics, and Complex/Intelligent Systems.
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.
Spark Discharge is a first-of-its-kind text, providing a comprehensive and systematic description of the spark breakdown of long gas gaps. It discusses the nature of a long spark, physical peculiarities of relevant gas discharge processes, methods and results of experimental studies, and analytical and numerical models. The most important applications in high-voltage engineering are covered in a single volume. The straightforward presentation of complicated materials, the deep insight into the nature of the processes, and the simplified mathematical descriptions of the phenomena, make Spark Discharge an excellent textbook for students and an indispensable reference for researchers, physicists, and engineers.
This latest addition to the Studies in Geophysics series explores in scientific detail the phenomenon of lightning, cloud, and thunderstorm electricity, and global and regional electrical processes. Consisting of 16 papers by outstanding experts in a number of fields, this volume compiles and reviews many recent advances in such research areas as meteorology, chemistry, electrical engineering, and physics and projects how new knowledge could be applied to benefit mankind.
Lightning represents a natural phenomenon of substantial interest. Due to its complex nature, research continues in many countries and reveals amazing results. Lightning is actively observed because of its relevance to Earth climate and air composition in addition to the classical aspects of related human fatalities and damage to forests, buildings, power lines, aircraft, structures and electronic devices. In this volume, the most important contemporary questions on lightning are addressed and analyzed under many experimental and theoretical aspects. Lightning detection techniques using ground-based and space-borne methods are described, along with network engineering and statistical analysis. Contributions detail research on atmospheric electricity, cloud physics, lightning physics, modeling of electrical storms and middle atmospheric events. Special phenomena such as triggered lightning and sprite observations are examined. Lightning-induced nitrogen oxides and their effects on atmospheric chemistry and climate are discussed. Each topic is presented by international experts in the field. Topics include: * air chemistry * convective storms * infrasound from lightning * lightning and climate change * lightning and precipitation * lightning and radiation * lightning and supercells * lightning and thunderstorms * lightning detection * lightning from space * lighting protection * lightning return strokes * observations and interpretations * spatial distribution and frequency * triggered lightning * weather extremes