No. 53: Sep-Oct 1987
Whistlers are, as their name implies, curious whistling noises heard on radio receivers. They are caused naturally by lightning, which sends radio noise travelling through natural "ducts" in the earth's magnetosphere. It has recently been discovered that some of the whistlers are synchronized in a way that strongly suggests that some event high up in the magnetosphere triggers some lightning discharges far below near the surface. In other words, lightning is not always a product of activity in the lower atmosphere.
(Armstrong, W.C.; "Lightning Triggered from the Earth's Magnetosphere as the Source of Synchronized Whistlers," Nature, 327:405, 1987.)
Comment. Ball lightning has been correlated with solar activity and other extraterrestrial influences. See GLB17 in our Catalog Lightning, Auroras, Nocturnal Lights. This book is described here.