In a breakthrough study, experts have identified the driving force behind Earth’s mightiest lightning strikes, known as “superbolts.” These phenomenally powerful electrical discharges are a thousand times stronger than ordinary lightning.
The research, led by physicist Avichay Efraim of the Hebrew University of Jerusalem, found that superbolts predominantly occur when a storm’s electrical charging zone is situated close to the Earth’s surface.
This proximity fosters the conditions necessary for generating superbolts, leading to “hotspots” seen above specific ocean areas and towering mountains.
Superbolts are rare, comprising less than one percent of all lightning strikes. Each superbolt carries around 300 billion volts compared to the 300 million volts in a typical lightning strike. The researchers noted that superbolts can cause major damage to infrastructure and ships.
“Superbolts, even though they’re only a very, very tiny percentage of all lightning, they’re a magnificent phenomenon,” said Efraim.
Previous research showed that superbolts tend to cluster over the Northeast Atlantic Ocean, the Mediterranean Sea and the Altiplano in Peru and Bolivia, which is one of the tallest plateaus on Earth. “We wanted to know what makes these powerful superbolts more likely to form in some places as opposed to others,” said Efraim.
The study brings to light the critical role of the charging zone’s location. Through analyzing lightning data, including time, location, and energy of selected strikes, the researchers were able to correlate superbolt strength with specific environmental conditions.
Among these, the height of the land or water surface, the altitude of the charging zone, and the temperatures at the cloud top and base were considered.
Notably, the study dismissed previously held beliefs from earlier research, revealing that aerosols exert a negligible influence on superbolt strength.
Instead, the shorter distance between the charging zone and the Earth’s surface emerged as a pivotal factor. The reduction in electrical resistance offered by this shorter distance enables the formation of higher-energy, and consequently, stronger lightning bolts.
Efraim’s team pinpointed three regions notorious for superbolt activity: the Northeast Atlantic Ocean, the Mediterranean Sea, and the Altiplano in Peru and Bolivia.
These areas share a common characteristic essential for superbolt generation – the minimal distance between the lightning charging zones and the Earth’s surface.
“The correlation we saw was very clear and significant, and it was very thrilling to see that it occurs in the three regions,” Efraim said. “This is a major breakthrough for us.”
The study, which provides the first explanation for the formation and distribution of superbolts worldwide, will help scientists determine how changes in climate could affect the occurrence of superbolt lightning in the future.
Efraim noted that warmer temperatures could cause an increase in weaker lightning, but more moisture in the atmosphere could counteract that.
In future research, the team plans to explore other factors that may contribute to superbolt formation, such as the magnetic field or changes in the solar cycle.
“There is much more unknown, but what we’ve found out here is a big piece of the puzzle,” said Efraim. “And we’re not done yet. There’s much more to do.”
The research is published in the Journal of Geophysical Research: Atmospheres.
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