Time resolved sprite imagery

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Abstract
Fleeting columns of luminosity occurring above large thunderstorms at 50–90 km altitude, presently known as sprites, were imaged with an intensified video charge coupled device (CCD) camera during a July 1995 ground‐based campaign near Fort Collins, Colorado. These unfiltered intensified images reveal detailed spatial structure within the sprite envelope. The temporal resolution of standard interlaced video imagery is limited by the 60 fields per second acquisition rate (16 ms). The specific CCD used here, however, is subject to bright events leaking into the readout registers, allowing time‐resolution on the order of the linescan rate (63 µs). Typical sprite onset is found to follow the associated cloud lightning by 1.5 to 4 ms. The onsets of the individual sprites within a cluster are generally, but not always, simultaneous to within 1 ms. Sprites tend to have a bright localized core, less than 2 km in horizontal dimension, which rises to peak intensity within 0.3 ms and maintains this level for 5 to 10 ms before fading over an additional 10 ms.