Boom! Powerful flashes light up the night during a storm. Lightning forms mostly over land, not over the sea. Recently, researchers discovered why. They studied data collected during 75,000 lightning storms over tropical regions near Earth’s equator. The scientists found that salty sea spray can keep lightning from forming.
Why? Lightning forms when water latches onto dust and other tiny particles in the air, forming droplets. These drops freeze into ice crystals. The crystals collide inside clouds and build up electric charges. It turns out that salt particles in sea spray make bigger cloud drops. The salt particles absorb more water, forming large drops that rain out instead of freezing. This prevents the cloud from charging up.
“I expected less lightning with more sea salt,” says Daniel Rosenfeld. He’s an atmospheric scientist who worked on the study. “But I didn’t expect the effect to be so strong. This was striking to me!”