There are those who think that lightning is all the same: a sudden flash, a thunder that makes you jump and off you go. But nature, as we know, loves to exaggerate. In the United States, a “megaflash” lightning bolt 829 kilometers long streaked across the sky from east of Texas to Missouri, earning it the title of longest discharge ever recorded on Earth. To give you an idea: it is the distance that separates Milan from Naples, a single flash that crossed an entire band of clouds without ever going out.
The term “megaflash” is not a journalistic gimmick: it is the official definition that scientists use to describe lightning that exceeds 100 kilometers in horizontal extension. Events so rare that they represent less than 1% of all observed storms. What makes them possible are the so-called mesoscalar convective systems (MCS), enormous storm structures that extend for hundreds of kilometers and which, within them, create “lakes” of electrical charge ready to unleash horizontal flashes of colossal proportions.
How scientists measured the record-breaking lightning strike
The company was identified and certified by Michael Peterson, a researcher at the Georgia Tech Research Institute, together with his team at the Severe Storms Research Center. To do so, they used satellite data collected by the Geostationary Lightning Mapper (GLM) on board the GOES-16 satellite. This instrument, thanks to its geostationary position, continuously observes electrical discharges in the atmosphere, recording every slightest light pulse.
This is because lightning does not emit continuous light, but a series of very rapid flashes, each lasting a few milliseconds. Without thorough analysis, the satellite could mistake thousands of consecutive pulses for distinct lightning strikes, instead of a single event. For this reason the research group used a sophisticated “clustering” system, i.e. an algorithm capable of uniting all the impulses that occur in the same place and in the same time interval, thus reconstructing the entire path of the discharge.
The end result was a continuous flash of 829 ± 8 kilometers, extending from east of Texas to near Kansas City, Missouri. A record that surpassed the previous record of 2020 (768 km, also in the United States) by 61 kilometers.
A fascinating but potentially dangerous phenomenon
Megaflashes are not only a spectacle of nature, but also a challenge for security and climate research. Such a long discharge can hit areas very far from the heart of the storm, putting at risk areas that apparently seem safe. This is why experts suggest updating lightning warning protocols, considering that a single flash can extend for hundreds of kilometers horizontally.
From a scientific point of view, these events are a real treasure: they help to understand how electrical charges accumulate and discharge in large storm systems and provide valuable data to improve weather and climate models. Discharges of this type, in fact, influence the chemistry of the atmosphere, contributing to the formation of nitrogen oxides, and in some cases can trigger fires or interfere with airline flights.
Record lightning and technology
In the past, such events were almost impossible to detect. Ground-based sensor networks, while efficient, were unable to “see” an entire lightning strike when it extended beyond the horizon. Today, thanks to satellites and new data analysis algorithms, we can finally observe the complexity and beauty of these atmospheric giants. And perhaps discover that the sky, even when it seems dark, always has a twist ready to illuminate half the world.
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