A strange glow in the treetops
Thunderstorms often amaze us with powerful lightning strikes, but scientists have now discovered a far subtler electrical spectacle. For the first time, researchers have observed trees producing a faint, ghost-like glow during thunderstorms. Scientists captured this unusual light using specialized ultraviolet cameras that detect extremely weak electrical discharges that human eyes cannot see.
Strong electric fields build up between storm clouds and the ground during a thunderstorm. Trees, which contain moisture and rise high above the ground, naturally conduct electricity. As a result, electrical charges move upward through the trunk and branches toward the leaves. When the charge concentrates at the tips of leaves and needles, it creates tiny electrical discharges known as corona discharges. These discharges generate a faint bluish glow that scientists compare to small sparks or flickering fireflies.
How scientists captured the glow
Researchers had suspected this phenomenon for decades because instruments often recorded unusual electrical activity in forests during storms. However, no one had ever directly observed the effect in nature.
To investigate further, scientists recreated thunderstorm conditions in laboratory experiments. They placed small trees beneath charged metal plates to simulate the intense electric fields produced by storms. In the darkened lab, they watched a dim bluish glow appear at the tips of the leaves.
After confirming the effect in the lab, the team took their equipment into the field. They mounted ultraviolet cameras and electric-field sensors on a mobile storm-chasing vehicle and monitored forests during thunderstorms. During one observation session, the cameras recorded 41 bursts of ultraviolet light, each lasting from a fraction of a second to about three seconds.
Why it matters
Although each flash is tiny, thousands of leaves across a forest could produce these discharges during a storm. Over time, repeated electrical bursts may slightly damage leaf tips or affect how trees interact with the atmosphere.
If humans could see ultraviolet light, a thunderstorm passing over a forest might reveal an extraordinary sight—countless tiny flashes shimmering across treetops like a swarm of glowing insects.
