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A single thundercloud which was developing near the coast of the Gulf of Finland at night is studied. Using three meteorological radars, two lightning detection systems, and a 3D numerical model, the physical processes which caused electrification of the cloud are analyzed. It is shown that the first lightning occurred in the period when a small area with graupel particles was observed in the upper part of the cloud. According to radar observations and numerical simulation, updrafts played an important role in the formation of that area and the microstructure of the cloud. Further increase in thunderstorm activity was associated with an increase in the cloud volume with graupel and hail. Analysis of the charge values of individual cloud fractions derived in numerical simulation shows hailstones to be the main carriers of a negative charge. [ABSTRACT FROM AUTHOR]

Characteristics of clouds which produced heavy precipitation in St. Petersburg and Leningrad oblast on June 18, 2020, are considered based on measurements with a C-band Doppler radar, Pluvio2 200 precipitation gauges, and a Blitzortung lightning detection system. To assess the intensity of precipitation, different values of the coefficients in the Marshall–Palmer Z–R relation are studied. We show that it is reasonable to use the specific differential phase to calculate the precipitation intensity when it exceeds 30 mm/h and precipitation consists of raindrops and hail. The top of the clouds exceeded 12 km, the maximal reflectivity was higher than 52 dBZ, and the maximal precipitation intensity could exceed 160 mm/h. A significant volume of a cloud was occupied by hail particles, which were recorded from the Earth's surface up to an altitude of 10 km. The highest reflectance was recorded in the precipitation zone, as well as in the hydrometeors melting area. All the clouds under study were thunderstorms. A sufficiently high correlation between the frequency of lightning and the intensity of precipitation is noted: the Spearman's correlation coefficient exceeds 0.7. [ABSTRACT FROM AUTHOR]

The paper presents results of the analysis of radar characteristics of clouds, including polarization characteristics, and lightning data for June 9, 2020, in the vicinity of St. Petersburg during intense thunderstorm activity. Characteristics of thunderclouds and clouds without lightning are compared. Statistical data about their differences are presented. The regression analysis of the correlation between the lightning flash rate and radar characteristics of clouds is performed using neural networks. The impact of these parameters on the lightning flash rate has been estimated. A mathematical expression for calculating the lightning flash rate by data on the differential reflectivity maximum of the cloud and the volume of its supercooled part with reflectivity of not less than 35 dBZ is derived. [ABSTRACT FROM AUTHOR]

The aim of this work is to summarize the results of the study of the development of a high depth thunderstorm over the waters of the Gulf of Finland. A waterspout was observed under the base of the cloud. Remote sensing methods were used in the study. The general conditions of atmospheric instability, microphysical and electrical characteristics of the cloud are considered. Cloud microphysics and the relation with lightning frequency are discussed. High correlation was discovered between the frequency of lightning discharges and the supercooled volume of the cloud, as well as the precipitation flux. [ABSTRACT FROM AUTHOR]

Characteristics of a thunderstorm cloud, from which a waterspout over Ladoga Lake appeared are studied with the use of the measurements from C-band Doppler Meteorological Radar (DMRL-C), a lightning detection system, and a high-altitude atmospheric radiosonde. Analysis of the indices of convective instability showed small to moderate probability of the development of intense convective processes. We applied algorithms for hydrometeor classification and updraft determination from DMRL-C measurements of polarization characteristics for the first time. These algorithms revealed the occurrence of large ice particles in the cloud at the beginning of thunderstorm activity and recorded an extended updraft associated with the waterspout. Analysis of dependences between the lightning frequency and different radar characteristics showed that the correlation is the strongest with a number of large ice particles characterized by the volume of supercooled (above 0°C isotherm) part of the cloud with reflectivity larger than 50 dBZ. [ABSTRACT FROM AUTHOR]

The results of simultaneous radar, radiometric, and lightning location measurements are analyzed to reveal interrelations between the characteristics of electric discharges and the parameters of a cumulonimbus cloud developing near Saint Petersburg. The dependences of the cloud electric activity on the radar characteristics as well as on the parameters derived from the Meteosat SEVIRI radiometer measurements are considered. It is found that lightning frequency highly correlates with the volume of supercooled cloud regions with high values of reflectivity. An increase in the lightning frequency occurs about 20 minutes after the moment when supercooled cloud volumes with reflectivity above 35–55 dBZ reach the maximum values. The maximum precipitation flux precedes the maximum lightning frequency. [ABSTRACT FROM AUTHOR]