July 1, 2003. Copyright, 2003, Graphic News. All rights reserved

Lightning jets may complete global electric circuit
By Joanna Griffin

LONDON, July 1, Graphic News:  The strikes last less than a second and are invisible to the naked eye, but the discovery of a new form of high-altitude lightning may help to complete our picture of the global electric circuit.

The journal Nature reports that scientists at National Cheung Kung University in Taiwan observed the phenomena firing up to 95km (60 miles) into the sky from the top of thunderclouds during storms over the South China Sea. The upward discharges, called Ògigantic optical jetsÓ, did not appear connected to ÒconventionalÓ lightning bolts between ground and clouds, it said.

Several forms of high-altitude lightning, including Òred spritesÓ Ð the luminous red glow that often accompanies thunderstorms Ð and Òblue jetsÓ have been documented in recent years. However, while red sprites travel downwards towards clouds but stop short of touching them, and blue jets appear as a narrow bolt, the giant optical jets stem from the core of the thunderbolt and form a cone shape over a wider area, taking on the appearance of a branching tree.

We know that ordinary ground-to-cloud lightning bolts occur because vast stores of negative particles massed at the bottom of thunderclouds collide with positive charges given off by objects on the ground. The scientists in Taiwan believe the gigantic upward surges occur when negative particles collect at the top Ð rather than at the bottom Ð of the clouds. They observed five gigantic jets in July 2002, all over the open sea.

Lightning is one of the most natural mechanisms for balancing the global electric circuit that runs between earth and atmosphere Ð the wide band of upper atmosphere that traps ions and electrons from space Ð yet it is also one of the most mysterious. The new research could help answer key questions, such as: how do the electrical charges contribute to ozone formation?
/ENDS