The traditional understanding of lightning formation, which attributes it to strong electric fields in storm clouds, is being challenged by new research indicating that relativistic electrons may play a key role.

What Causes Lightning? The Answer Keeps Getting More Interesting https://www.quantamagazine.org/what-causes-lightning-the-answer-keeps-getting-more-interesting-20260506/ #HackerNews #lightning #science #weather #phenomena #nature #discovery

What Causes Lightning? The Answer Keeps Getting More Interesting ---- - 2 days ago | 15 points | 0 comments - URL: https://www.quantamagazine.org/what-causes-lightning-the-answer-keeps-getting-more-interesting-20260506/ - Discussions: https://news.ycombinator.com/item?id=48037517 - Summary: Scientists are closing in on how lightning begins, but the answer is growing more complex. For centuries, researchers assumed storm clouds built electric fields strong enough to rip air molecules apart and trigger electron avalanches. Yet modern measurements show thunderstorm fields are typically too weak—only about a tenth the strength needed. Recently, physicists like Joseph Dwyer have proposed that "runaway" relativistic electrons create cascading avalanches, producing gamma rays and positrons that amplify the field in a feedback loop. NASA’s ALOFT mission detected flickering gamma-ray glows inside storms, providing strong evidence for this high-energy process. However, 2025 radio observations by Xuan-Min Shao suggest cosmic-ray showers from deep space may also trigger lightning, introducing a possible extraterrestrial component. Researchers now believe lightning initiation likely involves a combination of ice hydrometeors, relativistic electron avalanches, and perhaps cosmic rays. As instruments improve, scientists find storms are even stranger than expected, revealing that lightning is shaped by extreme physics once thought limited to supernovas and particle colliders.