Abstract:  Using the thunderstorm data from 1951 to 2010 in Dalian, the climatic characteristics of the thunderstorms were analyzed in terms of  methods of a mathematical statistics, a Mann-Kandall test and a Morlet wavelet analysis. The results show that the mean annual thunderstorm days increase in the recent 60 years, and the variation of the inter-annual and inter-decadal thunderstorm is significant. The annual thunderstorm day is in an increasing trend, and its ratio is the 0.5 d/ decade. The first thunderstorm date is ahead and the last thunderstorm date delays notably. The seasonal variation of thunderstorm is significant, and the frequency of thunderstorm is higher in summer than in autumn, while it is lowest in winter. Most thunderstorm appear during May to September, and those from June to August account for 60 %. There is a peak value for the mean monthly thunderstorm day, so are the mean monthly air temperature and the monthly precipitation. The maximum thunderstorm day occurs in July, and it decreases rapidly in October. Thunderstorm often occurs from 02: 00 to 06: 00 and seldom happens from 16: 00 to 20: 00. The thunderstorm days show 2-4 years and 14-16 years oscillating periods for inter-annual and inter-decadal variations, though these two periods are not significant. An abrupt change occurs in 1972.

Key words: Thunderstorm, Climate characteristics, Abrupt change test, Wavelet analysis