The characteristics and variation trends of temporal and spatial distribution of thunderstorms in the area of Linyi

Based on the observation of the thunderstorm days at ten weather stations in the area of Linyi, the characteristics of temporal and spatial distribution of thunderstorm days from 1962 to 2009 has been analyzed. The results indicate that the thunderstorm days are varied in different regions of the area, but the differences are small. The thunderstorm days decreased significantly by 3.4 days for every 10 years. The thunderstorm days for the whole region decreased sharply while the thunderstorm days in local region increased a little more. The month of July has the most thunderstorms and most of which are citywide storms, then the August followed. The decreasing tendency of thunderstorms is significant in summer and autumn and not obvious in spring. After 1972, the total number of thunderstorm days in Linyi decreased suddenly.