High-Speed Video Captures Dynamics of ‘Sprites’

With implications for the understanding of atmospheric phenomena and chemistry, a team of researchers at Duke University in Durham, N.C., FMA Research Inc. in Fort Collins, Colo., and SRI International in Menlo Park, Calif., has used submillisecond imaging to collect video of 10- to 100-ms-long luminous events known as “sprites.” Reporting in the Feb. 22 issue of Geophysical Research Letters, the group further describes the observation of the formation of bright “sprite beads” that may be sites where novel chemical species are created in the mesosphere.

For the high-speed video capture, which they performed in Colorado in July and August 2005, the scientists employed a Phantom v7.1 monochrome imager from Vision Research Inc. of Wayne, N.J., coupled with a third-generation image intensifier from ITT Industries Night Vision of Roanoke, Va. They recorded a series of 640 × 480-pixel images at rates of 5000 and 7200 frames per second of thunderstorms over Kansas and Nebraska. Seven nights of observations yielded 66 sequences that reveal how the sprites emerge a few milliseconds after a lightning stroke and evolve to form complex branched structures.