Coarse Sea Spray Keeps Lightning Strikes Away

By Hamodia Staff

YERUSHALAYIM — You may never have wondered why there is less lightning over oceans than over land; you might not even have noticed the difference. But scientists in Israel, China and the United States have been wondering—and now they say they have the answer.

Focusing on the role of small particles (aerosols) in controlling the amount of rain and lightning produced by clouds, they were able to explain why heavy ocean storms are accompanied by much less lightning than when a similar event occurs on land. They discovered that it is the larger, coarse sea spray that reduces the amount of lightning by as much as 90%, whereas smaller aerosols increase lightning. The size of particle also affects rainfall. 

It had always been assumed that the dearth of lightning in ocean storms was due to cleaner air over the ocean. However, observations had already shown that even highly polluted air is associated with reduced lightning at sea when sea spray aerosols are abundant. 

Hebrew University researchers in collaboration with scientists at Wuhan and Nanjing Universities in China, and the University of Washington, used satellite imagery to track clouds over land and sea.  This was combined with lightning measurements from the Worldwide Lightning Location Network (WLLN) and with data that provided information on the amount of aerosols in the clouds.

“We found a major cause for such a difference between ocean storms and those on land,” said HU Professor Daniel Rosenfeld. “The effect of aerosols on clouds has been underappreciated.  It needs to be incorporated into the models for better weather and climate prediction.”