scholarly journals Observation of a gamma-ray flash at ground level in association with a cloud-to-ground lightning return stroke

2012 ◽  
Vol 117 (A10) ◽  
pp. n/a-n/a ◽  
Author(s):  
J. R. Dwyer ◽  
M. M. Schaal ◽  
E. Cramer ◽  
S. Arabshahi ◽  
N. Liu ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Ground Level ◽  
Return Stroke ◽  
Cloud To Ground Lightning

Constraining the Origin Altitude of the first Satellite-Detected Reverse-Beam Terrestrial Gamma-ray Flash Produced by a Cloud-to-Ground Lightning Leader. 

2021 ◽  
Author(s):  
Jeffrey Chaffin ◽  
David Smith ◽  
Steven Cummer ◽  
Yunjiao Pu ◽  
Michael Splitt
Keyword(s):  
Gamma Ray ◽  
Radio Pulse ◽  
Low Frequency ◽  
Positron Beam ◽  
Strongly Correlated ◽  
Return Stroke ◽  
Cloud To Ground Lightning ◽  
Main Discharge ◽  
Lightning Leader ◽  
Meteorological Analysis

<p>We provide an updated analysis of the gamma-ray signature of a terrestrial gamma ray flash (TGF) detected by the Fermi Gamma-ray Burst Monitor first reported by Pu et al. 2020. Gamma-ray photons were produced 3ms prior to a negative cloud-to-ground return stroke and were close to simultaneous with an isolated low frequency radio pulse during the leaders propagation, with a polarity indicating downward moving negative charge. This ‘slow’ low frequency signal occurring prior to the main discharge has previously been strongly correlated with upward directed TGF events (Pu et al. 2019, Cummer et al. 2011) leading the authors to conclude that the Fermi detected counts just prior to the return stroke are the result of a reverse positron beam generating upward directed gamma rays.<span>  </span>We investigate the feasibility of this scenario and constrain the limits on the origin altitude from the perspective of the gamma-ray signature timing uncertainties, TGF Monte Carlo simulations, estimates of intrinsic brightness as a function of altitude, and meteorological analysis of the storm and its possible charge structure and altitude.</p>

Investigation of Zero Crossing Detection for First Return Stroke in Negative Cloud-to-Ground Lightning Flash

2019 ◽  
Vol 11 (3) ◽  
Author(s):  
Ahmad Idil Abd Rahman ◽  
◽  
Muhammad Akmal Bahari ◽  
Zikri Abadi Baharudin ◽  
◽  
...  
Keyword(s):  
Lightning Flash ◽  
Return Stroke ◽  
Zero Crossing ◽  
Cloud To Ground Lightning

scholarly journals Comprehensive Analysis of a Coast Thunderstorm That Produced a Sprite over the Bohai Sea

Atmosphere ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 718
Author(s):  
Cong Pan ◽  
Jing Yang ◽  
Kun Liu ◽  
Yu Wang
Keyword(s):  
Bohai Sea ◽  
Mesoscale Convective System ◽  
Convective System ◽  
Return Stroke ◽  
Absolute Value ◽  
Transient Luminous Events ◽  
Stratiform Region ◽  
Before And After ◽  
Mesoscale Convective ◽  
Cloud To Ground Lightning

Sprites are transient luminous events (TLEs) that occur over thunderstorm clouds that represent the direct coupling relationship between the troposphere and the upper atmosphere. We report the evolution of a mesoscale convective system (MCS) that produced only one sprite event, and the characteristics of this thunderstorm and the related lightning activity are analyzed in detail. The results show that the parent flash of the sprite was positive cloud-to-ground lightning (+CG) with a single return stroke, which was located in the trailing stratiform region of the MCS with a radar reflectivity of 25 to 35 dBZ. The absolute value of the negative CG (−CG) peak current for half an hour before and after the occurrence of the sprite was less than 50 kA, which was not enough to produce the sprite. Sprites tend to be produced early in the maturity-to-dissipation stage of the MCS, with an increasing percentage of +CG to total CG (POP), indicating that the sprite production was the attenuation of the thunderstorm and the area of the stratiform region.

scholarly journals Gamma Ray Showers Observed at Ground Level in Coincidence With Downward Lightning Leaders

2018 ◽  
Vol 123 (13) ◽  
pp. 6864-6879 ◽  
Author(s):  
R. U. Abbasi ◽  
T. Abu‐Zayyad ◽  
M. Allen ◽  
E. Barcikowski ◽  
J. W. Belz ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Ground Level

Radionuclides in the ground-level atmosphere in Vilnius, Lithuania, in March 2011, detected by gamma-ray spectrometry

2012 ◽  
Vol 109 ◽  
pp. 13-18 ◽  
Author(s):  
A. Gudelis ◽  
R. Druteikienė ◽  
G. Lujanienė ◽  
E. Maceika ◽  
A. Plukis ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Ground Level ◽  
Gamma Ray Spectrometry

scholarly journals Return stroke speed of cloud-to-ground lightning estimated from elve hole radii

2014 ◽  
Vol 41 (24) ◽  
pp. 9182-9187 ◽  
Author(s):  
P. R. Blaes ◽  
R. A. Marshall ◽  
U. S. Inan
Keyword(s):  
Return Stroke ◽  
Cloud To Ground Lightning

Ground-level observation of terrestrial gamma-ray bursts initiated by lightning

2017 ◽  
Author(s):  
Xiao-Qiang Li ◽  
Ru-Bin Jiang ◽  
Yi Zheng ◽  
Hong-Zhao Zhou ◽  
Bin Xing ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Ground Level ◽  
Gamma Ray Bursts

A Review of Positive and Bipolar Lightning Discharges

2003 ◽  
Vol 84 (6) ◽  
pp. 767-776 ◽  
Author(s):  
V. A. Rakov
Keyword(s):  
Forest Fires ◽  
Return Stroke ◽  
Winter Storms ◽  
Convective Systems ◽  
Lightning Channel ◽  
Different Types ◽  
Mesoscale Convective ◽  
Lightning Discharges ◽  
Cloud To Ground Lightning ◽  
Positive Return

Characteristics of lightning discharges that transport either positive charge or both positive and negative charges to the ground are reviewed. These are termed positive and bipolar lightning discharges, respectively. Different types of positive and bipolar lightning are discussed. Although positive lightning discharges account for 10% or less of global cloud-to-ground lightning activity, there are five situations that appear to be conducive to the more frequent occurrence of positive lightning. These situations include 1) the dissipating stage of an individual thunderstorm, 2) winter thunderstorms, 3) trailing stratiform regions of mesoscale convective systems, 4) some severe storms, and 5) thunderclouds formed over forest fires or contaminated by smoke. The highest directly measured lightning currents (near 300 kA) and the largest charge transfers (hundreds of coulombs or more) are thought to be associated with positive lightning. Two types of impulsive positive current waveforms have been observed. One type is characterized by rise times of the order of 10 μs, comparable to those for first strokes in negative lightning, and the other type is characterized by considerably longer rise times, up to hundreds of microseconds. The latter waveforms are apparently associated with very long, 1–2 km, upward negative connecting leaders. The positive return-stroke speed is of the order of 108 m s−1. Positive flashes are usually composed of a single stroke. Positive return strokes often appear to be preceded by significant in-cloud discharge activity, then followed by continuing currents, and involve long horizontal channels. In contrast to negative leaders, which are always optically stepped when they propagate in virgin air, positive leaders seem to be able to move either continuously or in a stepped fashion. The reported percentage of bipolar flashes in summer storms ranges from 6% to 14% and from 5% to 33% in winter storms. Bipolar lightning discharges are usually initiated by upward leaders from tall objects. It appears that positive and negative charge sources in the cloud are tapped by different upward branches of the bipolar-lightning channel.

scholarly journals In situ physical and chemical characterisation of the Eyjafjallajökull aerosol plume in the free troposphere over Italy

2014 ◽  
Vol 14 (2) ◽  
pp. 1075-1092 ◽  
Author(s):  
S. Sandrini ◽  
L. Giulianelli ◽  
S. Decesari ◽  
S. Fuzzi ◽  
P. Cristofanelli ◽  
...  
Keyword(s):  
Inductively Coupled Plasma ◽  
Gamma Ray ◽  
Fine Fraction ◽  
Chemical Properties ◽  
Analytical Techniques ◽  
Ground Level ◽  
Coarse Fraction ◽  
Volcanic Plume ◽  
Physical And Chemical ◽  
Aerosol Plume

Abstract. Continuous measurements of physical and chemical properties at the Mt. Cimone (Italy) GAW-WMO (Global Atmosphere Watch, World Meteorological Organization) Global Station (2165 m a.s.l.) have allowed the detection of the volcanic aerosol plume resulting from the Eyjafjallajökull (Iceland) eruption of spring 2010. The event affected the Mt. Cimone site after a transport over a distance of more than 3000 km. Two main transport episodes were detected during the eruption period, showing a volcanic fingerprint discernible against the free tropospheric background conditions typical of the site, the first from April 19 to 21 and the second from 18 to 20 May 2010. This paper reports the modification of aerosol characteristics observed during the two episodes, both characterised by an abrupt increase in fine and, especially, coarse mode particle number. Analysis of major, minor and trace elements by different analytical techniques (ionic chromatography, particle induced X-ray emission–particle induced gamma-ray emission (PIXE–PIGE) and inductively coupled plasma mass spectrometry (ICP-MS)) were performed on aerosols collected by ground-level discrete sampling. The resulting database allows the characterisation of aerosol chemical composition during the volcanic plume transport and in background conditions. During the passage of the volcanic plume, the fine fraction was dominated by sulphates, denoting the secondary origin of this mode, mainly resulting from in-plume oxidation of volcanic SO2. By contrast, the coarse fraction was characterised by increased concentration of numerous elements of crustal origin, such as Fe, Ti, Mn, Ca, Na, and Mg, which enter the composition of silicate minerals. Data analysis of selected elements (Ti, Al, Fe, Mn) allowed the estimation of the volcanic plume's contribution to total PM10, resulting in a local enhancement of up to 9.5 μg m−3, i.e. 40% of total PM10 on 18 May, which was the most intense of the two episodes. These results appear significant, especially in light of the huge distance of Mt. Cimone from the source, confirming the widespread diffusion of the Eyjafjallajökull ashes over Europe.

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