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An increase in the flux of energetic particles under thunderstorm clouds is a result of the multiplication and acceleration of particles of secondary cosmic rays in the electric field of the cloud. Study of the particle multiplication mechanisms requires an assessment of the electrical properties of clouds. In this paper, we propose a method for evaluating the electrical structure of a cloud that creates a flux of energetic particles. The developed technique for estimating the distribution of a charge in the cloud is based on the ground-based measurements of the electric field and energetic particle flux. The technique was used to study the clouds that create the descending fluxes of energetic particles observed at the Aragats Research Station. The characteristic charge distribution involves a two-layer structure with a charge density of 0.5–5 nC/m3 in the lower layer and –0.2…–3 nC/m3 in the upper layer. The total charges of the two charge regions are in the range of 1– 20 and –1…–30 C, respectively.

Thunderclouds act as the sources of energetic radiation, the main components of which are gamma particles and electrons. The radiation can be registered by satellite or ground-based detectors. The effect is caused by the bremsstrahlung of electrons accelerated by the cloud electric field. The study of high-energy atmospheric phenomena requires analyzing the data on the distribution of cloud particles and the electrical structure formed by them. In this study, the comparison of the information on meteorological conditions for energetic emission from thunderclouds obtained from satellite observations in the infrared and optical ranges is performed.

The most important factor determining the dynamics and structure of high-altitude discharges is the significant difference in atmospheric pressure along their length. The Sprite device was designed at the Institute of Applied Physics. It makes it possible to produce an extended concentration gradient of a neutral gas and ignite a large-scale electric discharge in it. This work presents the results of laboratory experiments simulating some properties of high-altitude discharges, primarily sprites and gigantic jets. A high-voltage pulse discharge, which is similar to sprites and gigantic jets in structure, is studied using a wide arsenal of laboratory diagnostics, including macroscopic electrophysical measurements, inductive probes for measurement of the spatial current profile, plasma microwave interferometry, and photography with nanosecond exposures. The similarity of laboratory and natural discharges is shown, and the physical problems and possible means of their solution with limited laboratory simulation are indicated.

A regional system of a short-term forecast of hazardous convective phenomena within WRF-ARW is described. It is shown that major maxima of errors in prognostic temperature and vertical velocity correlate with intense convective events, which indicates the need for additional verification procedures. A new method is proposed for forecasting hazardous convective events based on analyzing the simulated spatiotemporal distributions of the radar reflectivity of an event and comparing them with characteristic parameters (the duration, area, and maximum radar reflectivity) of intense convective events. Threshold values of the area and duration of the event are selected using field observations of powerful convective clouds, while the threshold of the maximum radar reflectivity in the vertical column is tailored for regional features. The method is verified against World-Wide Lightning Location Network (WWLLN) data and ground-based field measurements of the quasi-static electric field. It is shown that, for selected thresholds of duration (20 min) and area (50 km2), the optimal threshold of maximum radar reflectivity for Nizhny Novgorod oblast is 55 dBZ, in which case the Pierce skill score and the Heidke skill score take values of 0.61 and 0.62, respectively.

This review contains the most significant results of Russian studies in the field of atmospheric electricity in 20152018. It is part of the Russian National Report on Meteorology and Atmospheric Sciencesto the International Association of Meteorology and Atmospheric Sciences (IAMAS). The report was presented and approved at the XXVII General Assembly of the International Union of Geodesy and Geophysics (IUGG) 1. The review is followed by a list of the main published works on the studies of atmospheric electricity of Russian scientists in 20152018.

Modern methods for predicting thunderstorms and lightnings with the use of high-resolution numerical models are considered. An analysis of the Lightning Potential Index (LPI) is performed for various microphysics parameterizations with the use of the Weather Research and Forecasting (WRF) model. The maximum index values are shown to depend significantly on the type of parameterization. This makes it impossible to specify a single threshold LPI for various parameterizations as a criterion for the occurrence of lightning flashes. The topographic LPI maps underestimate the sizes of regions of likely thunderstorm-hazard events. Calculating the electric field under the assumption that ice and graupel are the main charge carriers is considered a new algorithm of lightning prediction. The model shows that the potential difference (between the ground and cloud layer at a given altitude) sufficient to generate a discharge is retained in a larger region than is predicted by the LPI. The main features of the spatial distribution of the electric field and potential agree with observed data.

We analyze the formulation of the problem of global atmospheric electric circuit modeling. It was shown that under some relatively simple and widely used simplifying assumptions this problem can be reduced to finding the temporal and spatial dependencies of the electric potential on the specified generators, which are determined by the external electric current density. They correspond to thunderclouds in the real atmosphere. The ionospheric potential (the potential difference between the upper and lower atmospheric boundaries) is not specified explicitly but can be uniquely determined from the solution. The formulations of the stationary and nonstationary problems are given in terms of the potential and their well-posedness is discussed. We obtained a number of analytical relations under some restrictions on the distribution of conductivity. They include the formulas which explicitly express the ionospheric potential in terms of the problem parameters. The examples of numerical calculations using the software developed on the basis of general formulations of the stationary and nonstationary problems are demonstrated.

Millisecond ultraviolet (240–400 nm) and red-infrared (610–800 nm) flashes were detected in the nighttime atmosphere with the scientific payload installed onboard the Universitetsky-Tatiana-2 micro-satellite. Flashes with various numbers of photons, from 1020 to 1026, were detected within the atmospheric area 300 km in diameter observed by the detector. The flashes differ in duration and temporal profile: from single short flashes ∼1 ms in duration to flashes with a complex profile more than 100 ms in duration. Different global geographic distributions are observed for flashes with different numbers of photons. Flashes with fewer than 1022 photons are distributed uniformly over the Earth’s map. Flashes with more than 1022 photons are concentrated near the equator and above the continents. Series of flashes were observed in one turn of the satellite when flying not only over thunderstorm regions but also over cloudless ones. The flash number distribution has been derived from the ratio of the numbers of red-infrared and ultraviolet photons. As applied to discharges in the upper atmosphere, whose glow is dominated by the emission in the first and second positive systems of molecular nitrogen bands (1PN2 and 2PN2), this distribution is equivalent to the flash altitude distribution in the atmosphere. The observed ratio of the numbers of photons in red-infrared and ultraviolet flashes agrees with the calculated one for electric discharges at altitudes higher than 50 km. In-orbit measurements of the charged particle flux (with a threshold energy for electrons of 1 MeV) provide no evidence for a synchronous occurrence of an ultraviolet flash and a burst in the particle flux in the orbit.

The first results obtained through the university small satellites program developed at Moscow State University (MSU) are presented. The space environment was investigated aboard two MSU microsatellites designed for scientific and educational purposes, Universitetsky-Tat’yana and Universitetsky-Tat’yana-2. The scientific equipment is described to study charged particles in near Earth space and atmospheric radiations in ultraviolet, red, and infrared optical wavelength ranges. The dynamic properties of fluxes of charged particles in microsatellite orbits are studied and findings are presented regarding specific parameters of solar proton penetration during the geomagnetic disturbances. Experimental results are considered concerning flashes of ultraviolet (UV), red (R), and infrared (IR) radiation that are transient light phenomena in the upper atmosphere. The space educational MSU program developed on the basis of the Universitetsky-Tat’yana projects is reviewed.

Physical mechanisms of formation of the global electric circuit (GEC) are considered and energy estimates are obtained for aeroelectric processes. Global thunderstorm activity, the electrodynamics of mesoscale convective systems, the electric fields of the magnetospheric dynamo and ionospheric dynamo region, and the electrostatic field of the global unipolar generator form a quasi-stationary aeroelectric state and maintain the balance of currents of the GEC atmospheric interval. In essence, the GEC is an open dissipative system including microphysical and electrohydrodynamic processes of generation and dissipation of the aeroelectric energy. The atmospheric electric field in the range of short-period aeroelectric pulsations has power-law spectra and contains coherent aeroelectric structures. The main GEC characteristics can serve as an indicator of a stationary state and spatiotemporal dynamics of atmospheric processes.