If a storm’s charging zone is near the surface, the resulting “superbolts” can be 1,000 times more powerful than regular lightning.
A new study shows that superbolts are more likely to impact the closer a storm cloud’s electrically charged zone is to land or ocean surfaces. These conditions cause supervolt “hot spots” in some oceans and over high mountains.
Superbolts make up less than 1% of all lightning, but when they do strike, they pack a powerful punch.The average lightning strike has approx. 300 million voltsthe authors say that superbolts are 1,000 times stronger and can cause significant damage to infrastructure and ships.
“Superbolts represent a small percentage of all lightning, but they are an amazing phenomenon,” said Avichai Ephraim, a physicist at the Hebrew University of Jerusalem and lead author of the study.
Previous research and new discoveries
a 2019 report They found that superbolts tend to be concentrated in the northeastern Atlantic Ocean, the Mediterranean Sea, and the Altiplano of 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 as opposed to others,” Ephraim said.
This new study provides the first explanation for the formation and distribution of supervolts on land and oceans around the world. This study Geophysical Research Journal: AtmosphereAGU journal dedicated to advancing our understanding of the interactions between Earth’s atmosphere and other components of the Earth system.
storm clouds often reaches 12-18 kilometers height (11.5 to 11 miles) and spans a wide temperature range. But for lightning to occur, clouds must cross the zero-degree temperature line. Celsius (32 degrees Fahrenheit). At temperatures below freezing, electrical charges occur in the upper reaches of clouds, creating lightning “charged bands.” Ephraim wondered whether changes in the height of the freeze line, and subsequently the height of the electrified belt, could affect a storm’s ability to form a supervolt.
Analysis of important factors
Previous studies have investigated whether superbolt strength is influenced by wave spray, channel emissions, ocean salinity, and even desert dust, but these studies have been limited to regional waters. At best, this could only partially explain the regional distribution of superbolts. The global explanation for supervolt hotspots remains elusive.
To determine what causes superbolts to concentrate in certain areas, Efraim and his co-authors needed to know the time, location, and energy of selected lightning strikes. radio wave detector set. They used these lightning data to extract key characteristics from the storm environment, including ground and water surface heights, charging zone heights, cloud top and base temperatures, and aerosol concentrations. They then looked at the correlation between each of these factors and superbolt strength, gleaning insight into what causes more powerful lightning and what doesn’t.
The researchers found that, in contrast to previous studies, aerosols had no significant effect on Superbolt’s strength. Instead, lightning energy increased significantly as the distance between the charged zone and the land or water surface decreased. For storms closer to the surface, shorter distances generally result in lower electrical resistance and therefore higher current flow, forming higher-energy bolts. And higher current means stronger lightning.
The three regions where superbolts occur the most have one thing in common: the Northeast Atlantic, the Mediterranean, and the Altiplano. That is, there is a short gap between the lightning charging belt and the ground.
“The correlation we observed was very clear and significant, and it was very exciting to see that it was occurring in three regions,” Ephraim said. “This is a big step forward for us.”
Implications and future research
Knowing that more supervolts occur when the distance between the Earth’s surface and the cloud’s charging zone is shorter will help scientists determine how climate change will affect future supervolt lightning occurrences. will help you. Ephraim said warmer temperatures could lead to an increase in weak lightning, but more moisture in the atmosphere could counteract it. There is no definitive answer yet.
The researchers will now investigate other factors that may contribute to the formation of supervolts, such as changes in the magnetic field and the solar cycle.
“There’s still a lot we don’t know, but what we’ve found here is a big piece of the puzzle,” Ephraim said. “And we’re not done yet. There’s still a lot of work to do.”
References: “Possible causes of the preponderance of superbolt lightning in the Mediterranean and Altiplano,” by Avichai Ephraim, Daniel Rosenfeld, Robert Holzworth, and Joel A. Thornton, September 19, 2023. Geophysical Research Atmosphere Journal.
DOI: 10.1029/2022JD038254