第一届未来大气科学论坛

Positive cloud-to-ground (+CG) lightning is more hazardous than its negative counterpart, yet our understanding remains limited due to the weak radiation from positive leaders. This study explores a positive CG lightning event following long intracloud (IC) lightning, using high-speed video and fast antenna mapping. Below the cloud base, decayed negative branches experienced consecutive re-breakdowns as bidirectional leaders beneath a horizontal negative channel. These bidirectional leaders advanced along the same channel, with the third eventually reaching the ground and producing a positive return stroke (RS) with a peak current of 157 kA. Post-RS, new side negative discharges propagated alongside the vertical RS channel, forming a continuing current (CC) lasting over 200 milliseconds. Our findings suggest that multiple side breakdowns of decayed negative branches facilitate the formation of downward positive leaders, ultimately leading to positive CG lightning. These side discharges are crucial in generating positive leaders from negative lightning channels.

positive cloud-to-ground lightning,side opposite-polarity breakdown,re-breakdowns of decayed negative channel