Unusual phenomenon in clouds triggers lightning flash

Researchers document unusual phenomenon in clouds prior to lightning flash.

LIGHTNING, LIKE THIS FLASH RECORDED AT THE KENNEDY SPACE CENTER IN FLORIDA, STARTS DEEP INSIDE A CLOUD. IN THEIR STUDY, UNH RESEARCHERS OBSERVED A POSSIBLE NEW WAY THAT LIGHTNING FORMS CALLED
LIGHTNING, LIKE THIS FLASH RECORDED AT THE KENNEDY SPACE CENTER IN FLORIDA, STARTS DEEP INSIDE A CLOUD. IN THEIR STUDY, UNH RESEARCHERS OBSERVED A POSSIBLE NEW WAY THAT LIGHTNING FORMS CALLED "FAST NEGATIVE BREAKDOWN."

For the first ever time, scientists have documented a distinct event that happens in clouds before lightning. This event is also dubbed as a fast negative breakdown.

Scientists at the University of New Hampshire Space Science Center, for the first time, have observed this breakdown that offers a new possible way for lightning to form. And the most fascinating is, it acts contrary to the current scientific view of how air carries electricity in thunderstorms.

Ningyu Liu, professor of physics said, “Despite over 250 years of research, how lightning begins is still a mystery. The process was totally unexpected and gives us more insight into how lightning starts and spreads.”

According to scientists, this study is a step forward toward detail insights on the lightning formation.

Recently, the problem of lightning initiation seemed to be solved with the discovery of “fast positive breakdown” of air, which matched the theory long held by lightning researchers. Fast positive breakdown involves the downward development of a pathway in the cloud, moving from the positive charge at the top of the cloud to the negative charge in the middle of the cloud. The pathway forms at one-fifth the speed of light and can trigger lightning.

Although, this new observation shows that an upward pathway—going in the opposite direction and just as fast—can be created in a thundercloud. It means, there is another way to start electricity in the air. Ultimately, this provides scientists with a new view of what’s possible inside a storm cloud.

Julia Tilles, a doctoral candidate in the UNH Space Science Center said, “These findings indicate that lightning creation within a cloud might be more bidirectional than we originally thought.”

Scientists made this observation in collaboration with a lightning research team from New Mexico Institute of Mining and Technology, the researchers documented fast negative breakdown in a Florida lightning storm at Kennedy Space Center using radio waves originating deep inside the storm clouds.

An array of ground-based antennas picked up the radio waves, which then allowed researchers to create a highly detailed image of the radio sources and identify this unusual phenomenon.

Scientists are continuing to develop the images from the data and hope to learn more about how often fast negative breakdown events occur and what fraction of them can initiate an actual lightning flash.

The study is published in the journal Nature Communications.