US researchers have made the startling claim that merchant ships are causing their own storms.
A team from the University of Washington has published a paper showing that lightning strikes are nearly twice as likely in busy shipping lanes, according to The Economist.
They studied 1.5bn strikes in the Indian Ocean and the South China Sea between 2005 and 2016.
The lane leading from the south of Sri Lanka to the northern entrance of the Straits of Malacca, and then to Singapore, was a particular black spot.
The report rules out lightning being caused by changes in vertical wind shear and differences in horizontal air movements, because these factors are the same outside shipping lanes.
And the research also ruled out the vessels themselves attracting the bolts, because the strikes tended to hit the water.
The team claims the most likely explanation is particulate pollution emitted by the ships.
The report said the high sulphur content produces soluble oxides that act as nuclei for the condensation of cloud-forming droplets.
These smaller droplets could be more easily carried upward into towering storm clouds, it added.
