Editing Lightning (section)

==== Upward streamers ====
[[File:Upwards streamer from pool cover.jpg| thumb|220x124px | right | Upwards streamer emanating from the top of a pool cover]]
When a stepped leader approaches the ground, the presence of opposite charges on the ground enhances the strength of the [[electric field]]. The electric field is strongest on grounded objects whose tops are closest to the base of the thundercloud, such as trees and tall buildings. If the electric field is strong enough, a positively charged ionic channel, called a positive or upward [[Streamer discharge|streamer]], can develop from these points. This was first theorized by Heinz Kasemir.<ref>Kasemir, H. W. (1950) "Qualitative Übersicht über Potential-, Feld- und Ladungsverhaltnisse Bei einer Blitzentladung in der Gewitterwolke" (Qualitative survey of the potential, field and charge conditions during a lightning discharge in the thunderstorm cloud) in ''Das Gewitter'' (The Thunderstorm), H. Israel, ed., Leipzig, Germany: [[Akademische Verlagsgesellschaft]].</ref><ref>Ruhnke, Lothar H. (June 7, 2007) "[https://archive.today/20110611231459/http://www.physicstoday.org/obits/notice_157.shtml Death notice: Heinz Wolfram Kasemir]". Physics Today.</ref><ref name="SA-Stephan">{{cite web |last1=Stephan |first1=Karl |title=The Man Who Understood Lightning |url=https://blogs.scientificamerican.com/guest-blog/the-man-who-understood-lightning/ |publisher=Scientific American |access-date=June 26, 2020 |date=March 3, 2016}}</ref>

As negatively charged leaders approach, increasing the localized electric field strength, grounded objects already experiencing [[corona discharge]] will [[Corona breakdown|exceed a threshold]] and form upward streamers.