What is the greatest length of a lightning bolt?

Dear Tom,
What is the greatest length of a lightning bolt?
John Sprinkle
Dear John,
The National Lightning Detection Network (NLDN) measures the length of lightning bolts by utilizing a very high-resolution, three-dimensional detection system that records the emissions of flashes in the very high-frequency range. The NLDN has been in place since the early 2000s and the network has measured many flashes over 100 miles in length. A lighting flash over Oklahoma on June 20, 2007, covered a horizontal distance of 199.5 miles, besting an earlier flash between Dallas and Fort worth, Texas, that measured 120 miles in length. The Oklahoma flash constitutes a new world record, certified by the World Meteorological Organization. Longer flash lengths have been measured in Brazil, but have not yet been certified by the organization.

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