Thunderstorm ground enhancements (TGEs) are fluxes of energetic particles multiplied in thunderclouds, which may be registered by ground‐based detectors. Using the Weather Research and Forecasting (WRF) Model, the state of the atmosphere with a 1‐km horizontal resolution is modeled for convective events accompanied by TGEs observed at the high altitude Aragats Research Station in Armenia (40.47 N, 44.18 E, 3,200 m above sea level). By comparing the data obtained in observations with the results of simulations using a microphysical parameterization for WRF, a technique is developed for estimating charge distribution parameters. A typical charge distribution in a TGE‐producing cloud is found to be well approximated by a two‐layered charge structure with a lower positive charge region formed by graupel particles and an upper negative charge region formed by snow particles. The characteristic charge density is 0.01 nC/m³ for the graupel cluster and −0.02 nC/m³ for the snow cluster. A vertical distance of about 1–2 km between the lower positive and upper negative layers is sufficient for the development of an energetic particle avalanche.

We present and discuss transient luminous events (TLEs) in the lower atmosphere, observed during large disturbances of the near-surface electric fields (NSEF) and coinciding with large enhancements of the particle fluxes (thunderstorm ground enhancements—TGEs). Despite large distances from the strongest electric field region, the maximum energy of TGE particles on 22 and 25 May 2018 reaches ≈40 MeV. Thus, the accelerating electric field reaches ≈2.0 keV/cm far from the zone of the strong lightning activity on the periphery of the storm. Light glows appearing simultaneously in the skies may be due to the local charge rearrangement generating a small illuminating discharge without initiating the lightning flash. This type of charge rearrangement does not lower the potential difference in the cloud, allowing the electron accelerator to operate and send particle fluxes in the direction of the earth’s surface.

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.

High-energy gamma radiation in the Earth's atmosphere is associated with the bremsstrahlung of Relativistic Runaway Electron Avalanches (RREA) developing in thunderstorm electric fields. In this paper, RREA development is studied in the system of two strong electric-field regions within thunderstorms, which accelerate runaway electrons toward each other. Such a system is called the simple reactor. It is discovered that the propagation of gamma rays and runaway electrons from one region to another leads to positive feedback. This feedback called the reactor feedback can make RREA self-sustaining, thus effectively multiplying high-energy particles inside thunderstorms containing the simple reactor. The spectrum and characteristic time scale of the simple reactor gamma radiation are in agreement with Terrestrial Gamma-ray Flashes (TGFs) data. The applicability of the simple reactor model to TGF is discussed, and the distinguishing observable properties of the simple reactor radiation during TGF and Thunderstorm Ground Enhancement are considered.

Sprite activity in the middle latitudes of the Northern Hemisphere is analyzed, with the example of the territory of Russia, aiming to facilitate the planning of observational campaigns in the region. The global model previously proposed by the authors is applied, using data from the WWLLN lightning detection network for 2015–2021. It is shown that the total number of sprites per year varies widely, from 394 in 2019 to 2354 in 2015. The most intense sprite activity almost always occurs in July, but in some years, there may be a shift to June (2015) and August (2021). The highest frequency of sprite initiation is observed in the Krasnodar Territory, Altai, and the Far East. Altai shows a high intensity of sprite activity every year, which is caused by the relief and underlying surface, while Krasnodar Territory and the Far East demonstrate sprites developed by incoming convective systems, which leads to high year-to-year variability.