When a storm’s impact zone is near the Earth’s surface, the resulting “super lightning” can be 1,000 times more powerful than regular lightning.
This is the conclusion of new research into so-called “superbolts”, which, although they only account for one percent of all recorded lightning strikes, can damage infrastructure and even ships.
“While superlightning represents only a very, very small percentage of all lightning, it is a magnificent phenomenon,” Avichay Efraim, a physicist at the Hebrew University of Jerusalem and lead author of this study, said in a statement.
A 2019 report found that superrays tend to cluster over the northeastern Atlantic, the Mediterranean and the Altiplano in Peru and Bolivia, one of the highest plateaus on Earth. “We wanted to know what makes these powerful superbolts more likely to form in some places than others,” Efraim said.
The new study provides the first explanation for the formation and distribution of superbolts over land and sea around the world. The research was published in the Journal of Geophysical Research: Atmospheres.
Storm clouds typically reach a height of 12 to 18 kilometers and cover a wide range of temperatures.
However, for lightning to form, a cloud must exceed the limit where the air temperature reaches 0 degrees Celsius. Above the frost line, in the upper part of the cloud, electrification occurs and the lightning “charging zone” is formed. Efraim wondered whether changes in the height of the frost line, and therefore the height of the stress zone, could affect a storm’s ability to form superbolts.
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Previous studies have examined whether the strength of superbolts could be influenced by ocean aerosol, emissions from shipping lanes, ocean salinity or even desert dust. However, these studies were limited to regional waters and could at most explain a portion of the regional spread of superrays. There has so far been no comprehensive explanation of the super radiation hotspots.
To figure out what causes superbeams to concentrate in specific areas, Efraim and his co-authors needed to know the time, location and energy of specific beams, which they detected using a series of radio wave detectors. They used this lightning data to extract key characteristics of storm environments, including land and sea surface elevations, stress zone elevations, cloud base and peak temperatures, and lightning concentrations. Aerosol sprays. They then looked for correlations between each of these factors and the strength of the super beam, gaining information about what causes stronger beams and what doesn’t.
The researchers found that, unlike previous studies, aerosols had no significant effect on the strength of the superbeams. In contrast, a smaller distance between the loading zone and the land or water surface resulted in significantly more energetic lightning strikes. Storms near the surface allow higher energy lightning to form because shorter distance generally means lower electrical resistance and therefore higher current. And higher current means stronger beams.
The three regions where most superbolts occur (Northeast Atlantic, Mediterranean and Altiplano) have one thing in common: short distances between lightning strikes and surfaces.
Knowing that a short distance between a surface and a cloud’s charging zone produces more superbolts will help scientists determine how climate changes might affect the occurrence of superbolts in the future. Warmer temperatures could lead to an increase in weaker radiation, but higher humidity in the atmosphere could counteract that, Efraim said. There is no definitive answer yet.
In the future, the team plans to explore other factors that could contribute to the formation of superrays, such as the magnetic field or changes in the solar cycle.