On the Problem of Critical Electric Field of Atmospheric Air

It is traditionally accepted to define the dielectric strength of air as an electric field corresponding to the balance between the rates of impact ionization and electrons’ attachment to neutrals. Its reduced value is known to be about 110 Td regardless of the altitude above the mean sea level. In this study, the altitude profile of the critical electric field of atmospheric air in the 0–40 km altitude range is specified. Unlike the conventional approach, a wide range of additional plasma-chemical processes occurring in atmospheric air, such as electron detachment from negative ions and ion-ion conversion is taken into account. Atmospheric air is considered to be a mixture of N2:O2 = 4:1 containing a small amount of chemically active small gas components, such as water vapor, atomic oxygen, ozone, and several types of nitrogen oxides. It is shown that the dielectric strength of air falls noticeably compared to its conventional value. The results of the study can be important to solve the problems of initiation and propagation of lightning discharges, blue starters, and blue jets.

Resolving Elve, Halo and Sprite Halo Images at 10,000 Fps in the Taiwan 2020 Campaign

After almost thirty years’ efforts on studying transient luminous events (TLEs), ground-based observation has confirmed the TLE family, including elves, halos, sprites, and blue jets, etc. The typical elve has the shortest emission time (<1 ms) in comparison with other TLEs. The second shortest is the halo emission. Although elves and halos are supposed to be more frequent than sprites, ground campaigns still have less probability of recording their images due to their fleeting and short emission. Additionally, the submillisecond imaging of elves, halos, and sprite halos helps us resolve their electro-optic dynamics and morphological features, but few have been reported in the literature. Our study presents the 10,000 fps imaging frames on elves, halos and sprite halos, compares their similarity and disparity, and analyzes their parent lightning properties with associated VLF and ELF data.

Broad-band electric field measurements above thunderstorms by the IME-HF instrument prepared for the TARANIS mission

&lt;p&gt;A broad-band analyzer of the IME-HF instrument (&amp;#8220;Instrument de Mesure du champ Electrique Haute Frequence&amp;#8221;) is prepared for the TARANIS (Tool for Analysis of RAdiation from lightNIng and Sprites) micro-satellite of the French space agency CNES. The spacecraft is based on the MYRIADE series platform. It will be launched on a Sun synchronous polar orbit at 700 km altitude. TARANIS will carry a complex payload of six scientific instruments to study radiation from lightning and optical phenomena (Transient Luminous Events) observed at altitudes between 20 and 100 km (blue jets, red sprites, halos, elves). The scientific instruments onboard TARANIS will detect electromagnetic radiation from very low frequencies up to 37 MHz, optical radiation, X rays (with an aim to study the Terrestrial &quot;Gamma-ray&quot; Flashes), and energetic electrons.&lt;/p&gt;&lt;p&gt;The IME-HF instrument will record waveform measurements of fluctuating electric fields in the frequency range from a few kHz up to 37 MHz, with the following scientific aims: (i) Identification of possible wave signatures associated with transient luminous phenomena during storms; (ii)&amp;#160;&amp;#160;&amp;#160; Characterization of lightning flashes from their HF electromagnetic signatures; (iii) Identification of possible HF electromagnetic or/and electrostatic signatures of precipitated and accelerated particles; (iv) Determination of characteristic frequencies of the medium using natural waves properties; (v) Global mapping of the natural and artificial waves in the HF frequency range, with an emphasis on the transient events. The instrument will be also able to trigger and record interesting intervals of data using a flexible event detection algorithm.&lt;/p&gt;

Survey on Electrical Activity in Earth’s Atmosphere

Lightning discharge is a spectacular, luminous and one of the most dangerous short lived phenomenon which occurs in the Earth’s atmosphere ranging from troposphere to the lower ionosphere. Lightning in troposphere is mainly classified as cloud-to-ground (CG) lightning, intra-cloud lightning and inter-cloud lightning discharges. It is assumed that these discharges are caused by the electrically charged thunderclouds. CG lightning has been studied more and is further categorized as positive CG and negative CG lightning. Positive CG lightning is more powerful and accounts only (5-10) percent of the total global lightning and may carry a peak current of >300 kA. An entire family of other electrical discharges also has been reported by the scientific community. They are called “Transient’s Luminous Events (TLE’s)”. TLEs occur from top of the thunderclouds up to the lower ionospheric altitudes. Their first visual evidence was documented in 1989. TLE’s are included as blue starters, blue jets, gigantic jets, red sprites, halos, and elves. They are named according to their optical properties, terminal altitudes and different shapes. It has been observed that TLE’s are associated with underlying thunderstorm activity and strong CG lightning. The exact physical mechanism of lightning and TLE’s and their association with the underlying thunderstorms is still unknown and the research is going on. In this paper, we will study the possible mechanisms of these electrical discharges, their inter-connection and impacts on the atmosphere. This papers is aimed at the readers generally are unfamiliar with the lightning characteristics. We hope that this article will increase the interest among the researchers.