From the 2nd to the 5th of October, the Czech Academy of Science in Prague hosted the 9th edition of the TEPA Conferences: Thunderstorms and Elementary Particle Acceleration. Over the last decade, high-energy physics in the atmosphere (HEPA) has undergone significant transformation. Correlated measurements of particle fluxes modulated by strong atmospheric electric fields, simultaneous measurements of the disturbances of the near-surface electric fields, and registration of various meteorological parameters on the Earth have led to a better understanding of the complex processes in the terrestrial atmosphere. 

The conference reports present the largest-ever particle fluxes detected at Lomnicky Stit and Aragats, showing the success of the first TGE research campaign on the mountaintops in Eastern Europe and Armenia. These extreme events shed light on the entire HEPA scientific field and indicate that thunderstorm ground enhancements (TGEs) are a universal physical phenomenon that originates in the thunderous atmosphere by the natural electron accelerator. 

Scientists in many countries are now monitoring particle fluxes around the clock using synchronized networks of advanced sensors that record and store multidimensional data. Reports from Japanese, Indian, German, Swiss, Czech, and Armenian physicists have shed new light on the terrestrial atmosphere full of radiation. These reports will help establish a comprehensive theory of cloud electrification and estimate the possible role of cloud radiation on climate change. 

The TEPA meeting is an opportunity for scientists to discuss current ideas and exploit synergies between Atmospheric and Cosmic ray physics.

Mileshovka Hill:  after climbing on the highest peak in the Bohemian Central Mountains. SEVAN detector 24/7 operates already 5 years, providing valuable data to Czech physicists

Balabek Sargsyan speaks about positron acceleration in thunderclouds and bursts of Natural gamma radiation. Session chair Tigran Karapetyan.