**6. Conclusions**

This paper analysed the importance of corona discharge in the lightning performance computation, taking into account the effect of corona discharge caused by indirect events. The corona effect has been implemented in the FDTD code for lightning-induced voltages computation following the approach proposed in Reference [12]. The number of flashovers considering the corona discharge can be compared to the ones obtained considering the finite ground conductivity, which represents a consistent part of the total. Moreover, a sensitivity analysis on the main causes leading to the corona discharge and to the enhancement of the number of dangerous events has been proposed, involving the surface state coefficient, the conductor diameter and the air humidity. The surface state coefficient variation leads to a linear percentage increase of the number of flashovers, except for very CFO values. The line diameter has a meaningful effect when we consider values lower than 20 mm: the function that better represents the behaviour of the percentage increase with respect to the diameter is exponential for CFO < 100 kV and linear for high CFO values. Finally, the effect of the air humidity is negligible. The sensitivity analysis allows an user to forecast the overall behaviour of his line with respect to the considered variables and can be taken into considerations in future IEEE Guidelines or CIGRE Working Groups Technical Brochures.

**Author Contributions:** Conceptualization, D.M.; methodology, D.M. and M.B.; software, D.M. and M.B.; validation, D.M.; data curation, D.M.; writing—original draft preparation, D.M.; writing—review and editing, D.M. and M.B. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Conflicts of Interest:** The authors declare no conflict of interest.
