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A new type of thunderstorm, responsible for the most intense lightning ever observed, has been identified by analysing satellite observations.

Eighty per cent of lightning occurs over land, where thunderstorms have stronger convection currents. These air currents bring smaller ice particles high up in the cloud and charge them, setting the stage for lightning.

But in terms of lightning density, which is the number of lightning flashes in a given time and area, the most extreme storms actually take place over the ocean, largely in the Gulf of Mexico and east of South Africa, according to research by at Los Alamos National Laboratory in New Mexico.

During one lightning-dense thunderstorm in the Indian Ocean in May 1998, lightning was flashing eight times per second, a rate so high that most humans would perceive the thundercloud as lit up continuously.

鈥淚t is the big kahuna,鈥� says Peterson. 鈥淭here are such high flash rates over the ocean that they even outshine all the land-based cases.鈥�

Some land-based weather patterns that span thousands of kilometres and contain multiple thunderstorms, known as mesoscale convective systems, technically have the highest overall flash rates, since each of their thunderstorms generates lightning. But flashes in lightning-dense marine thunderstorms happen within a smaller area, making them more intense.

At high rates, instruments fail to distinguish one flash from another and conflate them. Peterson noticed the May 1998 storm because it erroneously appeared to have a record-long 29-second flash. But using statistical averages for the number of pixel illuminations per flash, he calculated that it actually had some of the shortest successive flashes ever recorded.

Lightning-dense thunderstorms could cause damage if they make landfall, says at Texas A&M University. 鈥淚f you鈥檙e in a vulnerable area and this thing pops up, you鈥檙e almost guaranteed to be flooded out,鈥� he says. 鈥淪omething destructive is going to happen.鈥�

Peterson hopes to study how these thunderstorms develop using geostationary satellites and instruments placed on oil rigs, ships or planes.

鈥淎s we shift toward a warmer [climate] state, we need to know whether these extreme events are going to become more prominent, more frequent, potentially leading to further disasters down the road,鈥� he says.