Structure and Characteristics of a Сb during Lightning

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.