Cargo Ships Cause Lighting Strikes
Diesel emissions from ships cause twice as many lighting strikes to hit the world’s busiest shipping lanes, according to a study published in Geophysical Research Letters.
Scientists used 12 years of lightning strike data collected over shipping lanes in the northeastern Indian Ocean and the South China Sea, where emissions are the highest globally.
They made observations about the microphysics of cloud drop formation, interactions, and freezing.
Lightning strikes are more common along the same angular paths ships take along routes, and cannot be explained by meteorological factors, such as winds or the temperature structure of the atmosphere.
Lightning “enhancement” stems from aerosol particles such as PM2.5, organic carbon, and black carbon emitted in the engine exhaust of ships traveling along these routes.
Aerosol particles act as nuclei for a cloud drops, which allows more cloud water to be transported to high altitudes, where several types of molecules collide, producing electrification and lightning.
Adjacent areas with similar climates did not show the same lightning density.
The study’s authors concluded: “These shipping lanes are thus an ongoing experiment on how human activities that lead to airborne particulate matter pollution can perturb storm intensity and lightning.
“Our findings suggest that even small absolute increases in remote marine aerosol particles due to human activities could have a substantial impact on storm intensity and lightning.
“As such, there have likely been increases in storm vertical development and lightning in remote regions since the pre-industrial era, which has consequences not only for human life and property, but also for atmospheric composition and climate.”