Lightning location system strokes as ball lightning triggers – A follow-up study.

Correlating ball lightning (BL) reports with simultaneous lightning location system (LLS) stroke data can discover triggers for BL formation. A first 2018 study with 34 European BL cases and ALDIS LLS data found that 56% of the LLS correlated strokes had positive polarity, with a majority over 100 kA. A follow-up project with 58 European BL cases 1993-2023 examined LLS records 60 minutes before and after the reported BL in a 10 km radius. 53% of determinable BL-LLS stroke distances were under 1 km. 83% of the BL-correlated LLS negative strokes were under -30 kA, 71% of positive trigger strokes were over 50 kA (even 43% over 100 kA). The two hour LLS background activity around the BL events varied greatly from 1 to 2.678 strokes. The BL triggers within this LLS background activity were 35% isolated strokes, 24% at the end of activity, and 17% on a peak of activity. 48% of the isolated BL events had positive trigger strokes, 54% thereof over 100 kA. Further data analysis including a new flash grouping algorithm shows the complexity of interrelations between conventional lightning and BL events. BL formation checks with LLS have the potential to test and improve BL theories.