Velocities of sprite tendrils

[1] The University of Alaska deployed a high speed (1000 fps) camera at the Wyoming Infrared Observatory to observe sprites over Midwest U. S. thunderstorms as part of the 1999 NASA Sprites Balloon Campaign. Here we report on the velocity of development of downward spatial structures known as tendrils in several sprite events recorded during a large thunderstorm over eastern Nebraska the night of 18 August 1999. Downward tendril development occurred at velocities that varied by more than two orders of magnitude, ranging from similar to 10(5) to greater than or equal to 3 x 10(7) m/ s. The tendrils progressed through multiple velocity regimes, typically in the order fast- slow or slow- fast- slow. Examples are presented of multiple sets of temporally distinct tendrils that develop from the same sprite event and tendrils that have a horizontal component of expansion.