August 8, 2022 – Hebrew University researchers determined that coarse salty sea spray inhibits lightning over the ocean by as much as 90%, whereas smaller aerosols increase lightning.
In a new study published in Nature Communications, the researchers explain why heavy ocean storms have less lightning than those on land. Their work also clearly shows that the role of aerosols in clouds needs to be incorporated into climate models as particle size also affects rainfall.
Led by Professor Daniel Rosenfeld of the HU Institute of Earth Sciences and his doctoral student Zengxin Pan, the researchers fill in the gaps in previous theories about the differences in lightning between land and ocean storms. It had previously been assumed that the dearth of lightning in ocean storms was due to cleaner air over the ocean. However, it was already shown that even highly polluted air is associated with reduced lightning at sea when sea spray aerosols are abundant.
The HU 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 on aerosols in clouds.
“We found a major cause for such a difference between ocean storms and those on land,” says Prof. Rosenfeld. “The effect of aerosols on clouds has been underappreciated. It needs to be incorporated into the models for better weather and climate prediction.”
CITATION: Zengxin Pan, Feiyue Mao, Daniel Rosenfeld, Yannian Zhu, Lin Zang, Xin Lu, Joel A. Thornton, Robert H. Holzworth, Jianhua Yin, Avichay Efraim & Wei Gong, Coarse sea spray inhibits lightning, Nature Communications.
FUNDING: BSF, NSF.