Ghostly UV sparks illuminate forests as storm passes overhead
Thunderstorms can produce weak electrical discharges on plants below, but until now, they had never been observed in nature.
For nearly a century, scientists have been thinking about how storms can affect the forests below them, with many believing that storms can ignite weak electrical discharges on the plants below, which can strike the tips of leaves and branches. These phenomena, known as corona, had never been observed in nature until now.
A new study Published earlier this month in Geophysical Research Letters shows how the tips of tree leaves ignite with ghostly, ultraviolet sparks.
“These things really happen; we’ve seen them; we know they exist now,” said Patrick McFarland, a meteorologist at Pennsylvania State University and lead author of the study. statement.
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Before this study, scientists had observed in the lab how corona could be formed.
“In the lab, if you turn off all the lights, close the door and close the windows, you can barely see the corona. They look like blue flashes,” McFarland said.
Those observations showed that the electrical charge on top of a storm can generate an opposing charge on the ground below. Attracted to each other, the opposite charges will travel to the highest point it can reach. In the case of forests, this is the tree canopy. The tips of the leaves will then discharge electricity, producing a blue spark or corona.
To observe corona in the wild, McFarland and his team mounted a mobile weather station in a Toyota Sienna, complete with an ultraviolet camera. They then set out to search for the storm and kept making videos as they went. Analysis of video footage revealed that the corona was glowing at the tips of tree leaves and even bouncing from one leaf to another.
If humans could see in ultraviolet, it would probably appear as if the entire tree canopy was glowing, McFarland said. “It would probably look like a really cool light show, as if thousands of UV-glowing fireflies were landing on the treetops,” he said.
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