Significant enhancements of secondary cosmic rays and electric field at the high mountain peak of Lomnický Štít in High Tatras during thunderstorms

Abstract

High electric fields that occur in thunderstorm clouds in the Earth's atmosphere might accelerate energetic charged particles produced by cosmic rays. Such energetic particles, especially electrons, can cause additional ionization as they are multiplied and thus form avalanche of relativistic electrons. These relativistic electrons emit Bremsstrahlung in the X-or gamma-ray spectral ranges as they lose their kinetic energy via collisions. Thunderstorm ground enhancements (TGEs) of secondary cosmic ray fluxes recorded at the top of a sharp rocky mountain of Lomnický Štít in High Tatras (2634 m, Slovak Republic) are compared with simultaneous measurements of electric field at the mountain top and on its slope at the observatory of Skalnaté Pleso (1780 m). Results of measurements performed from May to September in 2017 and from May to October in 2018 are presented. The cosmic ray flux is measured by Space Environment Viewing and Analysis Network (SEVAN) and by neutron monitor with 1-s resolution. The TGEs that persisted usually several minutes were mainly detected in the SEVAN channel 1 which has the lowest energy threshold, about 7-8 MeV. A statistical analysis shows that these enhancements usually occurred (not only) during large values of vertical, upward-pointing electric fields measured just above the detector. It is shown that the measurement of electric field at Skalnaté Pleso, distant about 1.86 km from the mountain top is also partly correlated with the enhancements and can provide additional useful information about the distance or dimension of charge structure and dynamics of electric field, especially on short time scales. The enhancements usually did not exceed several tens of percent of background values. However, events that exceeded the background values several times were also recorded. The most extreme event exceeded the background values about 215 times. This event was also detected by other SEVAN channels and by the neutron monitor (~ 130% enhancement), which indicates a possibility of photonuclear reactions. The enhancements were often terminated by a nearby lightning.

Locating Thunder Source Using a Large-Aperture Micro-Barometer Array

“…It has response time of ∼0.1 s, the sampling rate of data is 25 Hz. The absolute values of electric field (PG) did not exceed several kV/m in Studenec during thunderstorms, which is different from measurements performed on high and sharp mounting peaks, where values reaching ∼100 kV/m were observed (Chum et al, 2020).…”

Hazards to Aircraft Crews, Passengers, and Equipment from Thunderstorm-Generated X-rays and Gamma-Rays

“…Gamma-ray fluxes, described as gamma-ray glows, etc., can last from seconds to minutes, and can produce gamma-ray photons with numbers exceeding the normal background level in some spectral ranges at least by one to two decades, while situations when the intensity of the glow is of the order of 10% of the background are also described [4,5,[13][14][15][16][17][18][19][20][21]26,27]. In principle, the generation of several subsequent and/or time-overlapping glows seems to be possible (see, e.g., [20,28]).…”

“…The detection of gamma-ray glows by ground-based or roof-mounted equipment is hampered by the absorption and scattering of photons by air, although this problem is reduced if observations are made at high-altitude mountain observatories or of thunderstorms with low-altitude charge-containing regions [4,5,13,14,[17][18][19][20][21]23,[26][27][28]30,31]. However, the altitudes at which commercial jet aircraft fly and the possibility of relatively short distances between the main region of the emission of high-energy photons and the aircraft mean that the aircraft are much less protected from such radiation by the air than is the case at ground level.…”

“…However, the altitudes at which commercial jet aircraft fly and the possibility of relatively short distances between the main region of the emission of high-energy photons and the aircraft mean that the aircraft are much less protected from such radiation by the air than is the case at ground level. It should be emphasized that there are several different assumptions about the physical nature of gamma-ray glows (see, e.g., [12,15,18,20,[22][23][24]26,28,29] and bibliographies therein). According to one author, some gamma-ray glows are generated by ball lightning [22,24,28,31].…”

Influence of Solar Wind on Secondary Cosmic Rays and Atmospheric Electricity

“…The electric field is measured on LS using an electric field mill EFM 100 sensor made by the Boltek company (Kudela et al, 2017). Relatively large values of the electric field are measured on the top of LS as it is a sharp, rocky mountain peak (Kudela et al, 2017;Chum et al, 2020). It should be noted that the mountain of LS represents a relatively conductive material, relative to the ambient air, and therefore locally enhances the intensity of the electric field.…”