Download or read book Electric Field Variations Produced by Natural and Triggered Lightning and Related Radar Measurements written by P. Laroche and published by . This book was released on 1980 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Electric Field Variations Produced by Natural and Triggered Lighting and Related Radar Measurements written by P. Laroche and published by . This book was released on 1980 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Observations and Modeling of Processes in Artificially Initiated triggered Lightning written by Christopher John Biagi and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In addition to the primarily optical measurements noted above, inferences are made of the vertical profiles of space charge density and electric field intensity above ground, as well as the line charge density that forms along the extending triggering wire in response to the ambient electric field. These inferences are made by comparing modeling and measurements of the ground-level electric field changes caused by the vertical extension of six grounded lightningtriggering wires that initiated lightning. The sustained upward positive leader inception heights and the ground-level electric field intensity at the wire launch time were linearly correlated with a correlation coefficient of -0.85. The transient current, electric field, and optical signatures produced by the sudden electrical breakdown processes (precursors) that occur at the top of the upward-extending lightning-triggering wires are examined. The lightning-triggering wire and its grounding system are modeled as uniform transmission lines with model predictions that are consistent with the measured wire-base precursor current signatures.

Download or read book Radar Detection of Lightning and Electric Fields written by James I. Metcalf and published by . This book was released on 1989 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt: In recent years, there has been increased interest in the use of radars to identify electrified clouds and to quantify electrification processes. This report surveys the use of radars to observe lightning and to observe the effects of electrical fields on the orientations of hydrometeors. Observations of lightning channels, conducted with increasing sophistication since the 1940's, have revealed the wavelength dependence of the reflectivity of lightning, the distribution of lightning echoes in storms, and the differential reflectivity of lightning. Observations of electrified clouds with polarization diversity radars during the 1970's and early 1980's revealed changes of orientations of ice crystals due to varying electric fields. These techniques can now be used in coordination with measurements of electrical fields and radio frequency emissions from lightning discharges to gain valuable new knowledge of the structure and evolution of electric fields in clouds. This report suggests several approaches to the continued investigations of electrical fields in clouds by radars. Atmospheric electricity. (EDC).

Download or read book Multiple station Measurements of Triggered Lightning Electric and Magnetic Fields written by David E. Crawford and published by . This book was released on 1998 with total page 566 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Proceedings in Atmospheric Electricity written by Lothar H. Ruhnke and published by . This book was released on 1983 with total page 450 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Study of the Effects of Triggered Lightning written by C. B. Moore and published by . This book was released on 1984 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt: The characteristics of lightning, artificially induced by wire-trailing rockets were measured in a cooperative program involving investigators from France, from the Flight Hazards Branch of Wright-Patterson Air Force Base and from New Mexico Institute of Mining & Technology. Lightning currents ranging from a few hundred amperes to a peak of 79 kA were measured. The waveforms of the electromagnetic signals produced by the lightning had associated magnetic field variations in excess of 10 T/s with rise times ranging from 40 ns to 1 microsecond. The development of an 11 cm radar was completed for a determination of the interaction between lightning and the surrounding atmosphere. Preliminary data on lightning echoes have now been obtained with it.

Download or read book Lightning Principles Instruments and Applications written by Hans Dieter Betz and published by Springer Science & Business Media. This book was released on 2008-12-04 with total page 641 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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

Download or read book Rocket Triggered Lightning Propagation and North Florida Thunderstorm Charge Structure written by John Turk Pilkey and published by . This book was released on 2014 with total page 312 pages. Available in PDF, EPUB and Kindle. Book excerpt: Propagate to and through the main negative charge regions. The locations of the main charge regions are found to vary based on the convective stage of the thunderstorm. The main negative charge region is found near the altitude of the 0 C level, typically located between 4 and 5 km, in dissipating thunderstorms. The evolution of the line charge density of the unbranched portion of two upward positive leaders (UPL) is calculated using LMA derived three-dimensional speed and measured channel-base current. The calculated line charge densities of the UPLs are found to increase as a function of time and altitude. The electric field changes due to the UPLs are modeled using the calculated line charge densities and compared to the measured electric field changes. The modeled electric field changes are found to be greater than the measured electric field changes for both UPLs studied.

Download or read book R D Abstracts written by Technology Reports Centre (Great Britain) and published by . This book was released on 1980 with total page 554 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Analysis of Lightning Field Changes Produced by Florida Thunderstorms written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-17 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: A new method is introduced for inferring the charges deposited in a lightning flash. Lightning-caused field changes (delta E's) are described by a more general volume charge distribution than is defined on a large cartesian grid system centered above the measuring networks. It is shown that a linear system of equations can be used to relate delta E's at the ground to the values of charge on this grid. It is possible to apply more general physical constraints to the charge solutions, and it is possible to access the information content of the delta E data. Computer-simulated delta E inversions show that the location and symmetry of the charge retrievals are usually consistent with the known test sources. Koshak, William John Marshall Space Flight Center CHARGE DISTRIBUTION; ELECTRIC CHARGE; ELECTRIC FIELDS; INVERSIONS; LIGHTNING; THUNDERSTORMS; CARTESIAN COORDINATES; COMPUTATIONAL GRIDS; COMPUTERIZED SIMULATION; DIPOLES; LINEAR SYSTEMS; POINT SOURCES; SYMMETRY...

Download or read book Nonlinear and Environmental Electromagnetics written by International Union of Radio Science. Commission E. Workshop and published by Elsevier Publishing Company. This book was released on 1985 with total page 416 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Correlated Measurements of UHF Radar Signatures RF Radiation and Electric Field Changes from Lightning written by D. M. Le Vine and published by . This book was released on 1983 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: During Storm Hazards - 82, simultaneous measurements were made of radar echoes, fast and slow field changes and RF radiation from lightning near the Wallops Flight Facility. RF radiation and radar echoes were also obtained during periods when the NASA F106 research aircraft was struck by lightning. These data are presently being used to better understand the electrical processes which occur during strikes to the aircraft. Preliminary conclusions based on data obtained in 1982 verify that the events recorded aboard the aircraft occurred during lightning but also indicate that they occur with surprising frequency very early in the flash. (Author).

Download or read book Theoretical and Experimental Investigations of the Electromagnetic Fields and Energetic Particles Associated with Thunderstorms and Lightning written by Shahab Arabshahi and published by . This book was released on 2014 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt: Despite more than 250 years after Benjamin Franklin's kite experiment, lightning is still one of the mysteries of nature. We still do not understand how lightning works at the most basic level. Traditionally, lightning used to be studied using classical electrodynamics. However, in the last decade or so, the observation of many high energy phenomena associated with lightning and thunderclouds (e.g., X-rays from lightning leaders, TGFs, X-ray and gamma-ray glows from thunderstorms, etc.), started a new path in studying lightning and thunderstorms. It is suggested that energetic radiation in our atmosphere is the result of bremsstrahlung scattering of energetic electrons, called "runaway electrons", from air molecules and atoms. There are three main mechanisms for the production and propagation of runaway electrons; thermal (cold) runaway electron production, Relativistic Runaway Electron Avalanches (RREAs), and relativistic feedback mechanism. Depending on the voltage difference of the runaway zone and the existence of an energetic seed particle, one of these mechanisms is at work.We have performed theoretical, modeling, and experimental studies of all three runaway electron mechanisms. The Relativistic Runaway Electron Avalanche process seeded by Extensive Air Showers (RREA-EAS) has long been suggested to be responsible for the production of Compact Intracloud Discharges (CIDs). We developed a fluid model based on RREA-EAS and simulated the production of CIDs. We compared our simulation results with observational data from the Lightning Observatory in Gainesville, FL and showed that one can find the fields which can produce Narrow Bipolar Pulses, but these fields are not realistic for thunderclouds and the required energy of EAS is too high. Our results do not support the RREA-EAS hypothesis, as it relates to CIDs. A high-energy spectrometer (ARIS-S) for the detection of energetic radiation from leaders in lightning was designed, constructed and deployed at the International Center for Lightning Research and Testing (ICLRT). X-ray pulses from rocket-triggered lightning events were collected and the results produced the world's first detailed measurement of X-ray spectrum from lightning. Our analysis showed that the spectrum of X-rays from leaders is much too soft to be consistent with RREA and the cold (thermal) runaway mechanism is a viable candidate for the production mechanism of runaway electrons at leader tips of lightning. Finally, in order to determine the importance of the discharge currents caused by the runaway electrons and the role of relativistic feedback, we successfully designed, developed, and tested a balloon payload for the in situ measurement of energetic electrons and gamma-ray photons from inside thunderstorms including many other environmental measurements (e.g., GPS location, acceleration, orientation, etc.). In 2013 we successfully measured the fair weather background radiation profile as a function of height. The fair weather data agreed well with theoretical predictions. In the summer of 2014 we had five balloon launches with four of them measured gamma-ray glows from thunderstorms and at least one of them entered the runaway electron source region. We also observed two events, on two separate balloon launches, with hour-scale long excess radiation. Furthermore, we analyzed our data in accordance with the Kennedy Space Center Lightning Mapping Array (KSC LMA) data and showed that by combining them we can get a great insight regarding the electric field at the source of the gamma-ray glows and runaway electron avalanches.

Download or read book Publications Abstracts written by Environmental Research Laboratories (U.S.) and published by . This book was released on 1993 with total page 234 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Study of Spacetime and Electrical Properties of Artificially Triggered and Natural Lightning Discharge Based on VHF and Electric Field Observations written by Yanchi Shen and published by . This book was released on 2017 with total page 195 pages. Available in PDF, EPUB and Kindle. Book excerpt: The space charge density of L1a increased as the leader developed. The general range of the space charge density of L1a under 680 m high was -3 nC/m3 to 5 nC/m3, with some unipolar pulses (-31 nC/m3 to 72 nC/m3). The space charge density of L1a above 680 m high was very small and ranged from -0.8 nC/m3 to 0.4 nC/m3. These pulses indicate that there were positive charge groups present. The allocations of the pulses of the space charge density were the same as for the bipolar pulses of the background electric field, the pulses of the negative line charge density, and for the big curves of the L1a channel. Therefore, the complexity of environmental electrical conditions can cause distortion of the leader channel. Similar conclusions can be drawn for the L2a channel, except in the smaller range of the space charge density. The range of the space charge density for L2a was from -0.4 nC/m3 to 0.45 nC/m3, with some large pulses ranging from -8 nC/m3 to 8 nC/m3. Due to the limitations of this approach, the ranges of the background electric field and space charge density may not be accurate, but the trends and the pulses further our understanding of the propagation of lightning discharge. Fourth, using a similar approach as for the triggered lightning discharge, we studied the spatial and electrical properties of natural lightning discharge. As we had no optical images of the natural lightning, its channel was rebuilt by the data of the VHF source radiation from the broadband interferometer with a presumed height of the lightning initiation position in the cloud. Based on the approximate channel that was rebuilt, it was found that this discharge was a downward stepped-leader initiated negative cloud-toground discharge with only one leader/return stroke process. The general speed of the leader when it propagated horizontally in the cloud was 0.4 ×106 m/s to 1 ×106 m/s, and when it propagated vertically was about 3.5 ×104 m/s to 1.5 ×105 m/s. The average speed was 7.0 ×10 4 m/s. As it went downward, the leader branched significantly. Additionally, while the leader moved downward, the VHF sources (breakdown processes) within branches around the leader tip frequently showed backward movements (about 400 m) with a speed of about 2 ×106 m/s, which is much faster than the average leader downward speed of 7.0 ×104 m/s. Electrical properties of the leader above 3000 m were also obtained based on a rough leader channel without branches and backward movements. With the development of the leader channel, the leader brought negative charges downward along the leader channel and the changes of the electric field increased. The estimated line charge density showed a trend to increase as the leader propagated downward, ranging from -0.1 mC/m to -1.1 mC/m. The pulses of the leader charge density show that the leader transported plenty of negative charge when it propagated along the leader channel, which may have caused the curves of the leader channel. Lastly, the findings and their scientific merits are summarized and discussed. Through our study of artificially-triggered lightning discharge and natural lightning discharge, we know that while the cases analyzed here are special, they have some common features. The range and the trend of the electrical and spatial properties show the applicability of the approaches and models in my study. The changes of electric field observed on the ground, the space evolution of the lightning leader channel and the propagation speed of the leader channel were closely related to the spatial initial environment of the lightning discharge. Differences in environment can cause different propagated movement of lightning discharge, depending on the results. This means that a different distribution of space charge or a complex environmental electric field profile can lead to a complex leader channel and movement. A stronger background electric field indicates stronger VHF radiation sources, a faster speed of the leader channel, a more complex lightning channel and more charge in the leader channel. In future research, we need to improve the methods of observation, to obtain more detail of the lightning discharge. With high resolution observations and more sophisticated detail for the lightning discharge, additional spatial evolution characteristics and electrical properties of the discharge, such as the charge density of the branches of the leader channel, can be analyzed. The accuracy of the results also will be improved. Lightning discharge with more complicated initial electrical environments also can be studied in the future, using observation and simulation.

Download or read book VII International Conference on Atmospheric Electricity June 3 8 1984 Albany N Y written by and published by . This book was released on 1984 with total page 540 pages. Available in PDF, EPUB and Kindle. Book excerpt: