Mesoscale Observations of Lightning from Space Shuttle.

Motion pictures have been taken at night by astronauts on the space shuttle showing lightning discharges that spread horizontally at speeds of 10⁵ m s¹ for distances over 60 km. Tape recordings have been made of the accompanying optical pulses detected with a photo-cell optical system. The observations show that lightning is often a mesoscale phenomenon that can convey large amounts of electric charge to earth from an extensive cloud system via a cloud-to-ground discharge.