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Science Blog ZINC PROJECTS

Uncover mechanisms of different types of lightning

Date: 26-Apr-08
Author: Penn State University

The mechanism behind different types of lightning may now be understood, thanks to a combination of direct observation and computer modeling reported by a team of researchers from New Mexico Tech and Penn State.

Most people see lightning strikes that go from clouds to the ground, but some lightning goes upward, forming blue jets and gigantic jets. Perhaps the most dangerous lightning appears as "bolts from the blue" -- lightning that begins upward, but then moves sideways and then downward to hit the ground as much as three miles [5 km] from a thunderstorm.

Courtesy: NOAA Photo Library

About 90 percent of lightning occurs inside clouds and is not visible to the casual observer. The researchers ... discovered that upward and sideward lightning events occurred shortly after normal downward lightning bolts occurred or intracloud lightning produced a local charge imbalance in the cloud.

Lightning forms in clouds when different areas of the cloud become either positively or negatively charged. Once the electric field near a charged area exceeds a certain propagation level, lightning occurs. The type of lightning depends on where the charge builds and where the imbalance in charge exists in the clouds.

Full story: Uncovering the mechanisms of lightning varieties

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