How does lightning pick a target? New research shows the ‘final jump’ before a strike

A series of photos taken at 1/380-thousandth of a second have revealed something that has long puzzled scientists: The “fleeting moment” lightning chooses where to strike.

That moment is called the “final jump,” and it happens when negative charges from thunderclouds reach down and “attach” to positive charges rising from the ground, the American Geophysical Union reported Monday in its Geophysical Research Letter.

Thunderclouds will often generate many “fingers” of lightning (also called leaders) simultaneously, “but generally only one lightning channel will form, and its path is unpredictable,” the AGU said in a release.

The discovery puts experts no closer to predicting where lightning will strike, but it does show clouds alone do not choose the point of impact — like lasers fired from a rocket ship.

“It is a very important issue because, in lightning development, there are a lot of branches,” according to atmospheric physicist and study co-author Rubin Jiang of Chinese Academy of Sciences.

“The target of the lightning strike is not determined at the beginning when it initiates from the cloud. The attachment process... eventually determines the object that’s struck by the lightning flash. Our study makes more specific the breakthrough phase. ... the so-called ‘final jump’,” he said.

The high-speed video used in the study was taken as lightning struck a 1,000-foot-tall meteorological tower in Beijing, China, according to the AGU. In the images, charges from a thundercloud and the ground reached to within 75 feet of each other when they suddenly made the jump to “a single luminous thread,” according to the study.

This thin connection lends “support to the idea that the early contact between streamers of upward and downward lightning leaders sets the route of the lightning flash,” the release said.

“Final jumps” happen so quickly that scientists have never been able to figure out whether multiple lightning leaders merge to make the connection, or if a “single positive and negative streamers meet ... and become the sole channel that heats up to the lightning flash,” experts say.

“The new study suggests the single connection of the second scenario is more likely,” the report says.

Lightning’s unpredictable nature makes it among the deadliest of natural wonders. NOAA reports lightning kills an average of 49 people annually in the U.S. “and hundreds more are injured,” including some who suffer with “lifelong neurological damage.”

Numbers were down in 2020, with 17 deaths, NOAA says. Florida and Texas led with three deaths each, followed by two each for North Carolina and Pennsylvania, NOAA reports.

The fatalities included people who were doing yard work, getting out of their car, and playing sports when they were struck, NOAA says.

This story was originally published February 1, 2021 at 4:23 PM with the headline "How does lightning pick a target? New research shows the ‘final jump’ before a strike."