Lightning initiated from tall structures - A review

Current parameters of tower triggered lightning are of interest for the lightning protection of high objects, such as wind turbines. Initiation conditions of upward lightning are still subject of ongoing research and probably needs consideration of local conditions. In this paper results of measurements of upward lightning from the Gaisberg Tower (GBT) in Austria are summarized and compared with some other measurements on towers or rocket-triggered lightning. Upward lightning initiated by a positive upward leader is the most common type (93%) of lightning observed at the GBT, nevertheless 3% of the discharges are bipolar and 4% of the tower flashes are lowering positive charge to ground. Positive flashes are initiated by a negatively charged leader and short current pulses associated with the stepping leader process are observed.