SPRITES, ELF TRANSIENTS, AND POSITIVE GROUND STROKES

In two summertime mesoscale convective systems (MCSs), mesospheric opt ical sprite phenomena were often coincident with both large-amplitude positive cloud-to-ground lightning and transient Schumann resonance ex citations of the entire Earth-ionosphere cavity. These observations, t ogether with earlier studies oi MCS electrification, suggest that spri tes are triggered when the rapid removal of large quantities of positi ve charge from an areally extensive charge layer stresses the mesosphe re to dielectric breakdown.