Triggered lightning strokes originating in clear air

During the 1978 campaign of the triggered lightning program at Saint‐Priyat d'Allier (France), simultaneous data from a movie camera, a coaxial shunt amperometer, a network of electric field mills, and a weather radar, were collected during the initial phase of a particular triggered event. These data are shown to exhibit a high degree of consistency, leading to the conclusion that charges totaling several coulombs were present in cloudfree air in the vicinity of a stormy area.