Thunderstorms, lightning and solar activity—Middle Europe

Thunderstorm–solar activity relationships have been studied in the past, mostly with records of audible thunder correlated with sunspot number ( R). Our study is new in two aspects: firstly, it uses measured lightning frequency, and secondly, these records are correlated not only with R but also with other parameters characterising solar activity, namely Ap, F10.7 and cosmic ray flux. With data from the German lightning detection system BLIDS we obtain a significant correlation of lightning frequency with Ap and R, and a significant anti-correlation with cosmic ray flux. A similar analysis with data from the Austrian system ALDIS yielded inconclusive results. Both observations and earlier findings of spatially varying correlation coefficients between R and thunderstorm frequency can probably be reconciled invoking new ideas about the transmission of a solar activity signal to the lower atmosphere. In these new developments planetary waves play a crucial role.