Ecology & Safety, Volume 10, 2016

Streszczenie: Commonly the severe convective storms are not only attended by heavy rain events, but also by hail and thunderstorm activity, which on their own account cause material damages and life loses. According to Bulgarian Agency of Civil Defense and media the mean annual numbers of victims of thunders increased during the last years are about 10 people/per year The aim of the study is to present time-space variations of thunderstorm events in Bulgaria during the period 1961-2010. Visual thunderstorm observations at 42 meteorological stations with altitude below 800 m are used in a study. By the orographic and climatic features the territory of Bulgaria are divided into 6 parts and thunderstorms annual, decadal and monthly distribution and variability is presented for each of them. The comparison of two investigated periods (1961–1990, 1991–2010) show that the mean number of registered thunderstorm days increase during the second period. This growth is statistically significant only in NE Bulgaria and partially in SC Bulgaria. The 75% of all thunderstorm days is observed in warm half of the year between May and August. In the same time the significant increase of thunderstorm events in all regions from North Bulgaria during the winter months December, January and February after 1991 is established. The regime of wide-spread stormy fays for 10-days period during the warm half of the year (April-September) is compared for the two periods: 1961-1990 and 1991-2010. The increase in number of those hazardous events during the months from the end of the summer is received.