first_imgThe lifetime of whistler ducts is determined in view of whistler data recorded over a 3-hour period at Sanae and Halley (L = 3.98 and 4.24, respectively) in South Africa, on July 11, 1976. The observation of lifetimes as short as 30 min is held to have important implications for current theories of ducts, by furnishing a time constraint.last_img