Sprite observations in the Northern Territory of Australia

Abstract

Sprites, a form of brief luminous discharge in the upper atmosphere above a thunderstorm, were observed and imaged on two video cameras in Australia's Northern Territory. These were the first such ground-based observations made outside the United States. Sprite discharges typically took place between the altitudes of 50 km and 80 km and spanned an average width of 44 km. Many of the sprite events were of long duration, with an average of 145 ms. These spatial and temporal features were similar to those observed from the ground and the air in the United States. During the longer events, some luminous discharge elements were observed to decay as other new elements formed. As the new elements were often laterally displaced from the old, the sprites sometimes appeared to dance across the sky. This phenomenon has been observed in Colorado and named "dancing sprites." The lateral progression of sprite elements observed in the Northern Territory was overwhelmingly in one direction and covered distances of up to 90 km. Copyright 2000 by the American Geophysical Union.