William Brune
Coronas glow at the tips of fir needles, induced by metal plates transported in the laboratory. These weak electrical discharges subtly singe the tips of leaves and needles.
Every time a heavy enough storm passes over a forest, it could be making the trees glow. Not with fire, not with lightning, but with a faint, flickering electric light that pulses through the leaves and bounces from branch to branch as the storm passes overhead.
No human eye has ever seen it. AND invisible without equipment that only existed recently. And during almost a hundred yearsscientists could only theorize that this happened at all.
Now, a team of researchers from Pennsylvania State University, in the USA, has confirmed it. Using an ultraviolet camera built from scratch for this purpose, they captured the first direct observations ever recorded of what is known as crown discharges on trees during real storms
The discovery was presented in a recently published in the journal Geophysical Research Letters.
As crownsas the phenomenon is known, are failed electric shocks which form on the leaves of trees when storm clouds pass overhead and charge the air with electricity.
Glow with ultraviolet lightcarry minute electrical currents and jump erratically from leaf to leaf as the storm progresses. There were suspicions, they were theorized, and even proposed as a scientific explanation for the burning bush from the Bible.
Until this study, no one had ever observed them directly in nature, measuring its intensity or documenting its behavior, notes .
Observations across five storms from Florida to Pennsylvania suggest that coronas could be a widespread phenomenon in the treetops under electrified stormsforming on the most favorably positioned leaves while the storm’s charged core is overhead.
According to the study authors, the observations “give rise to a view of extensive sparkling crown glitter bands as the electrified storm passes over a forest.”
If this is confirmed with further research, forests around the world could to be illuminated silently during storms in a way humanity has never witnessed.
Why does it matter that trees shine
“Crowns on trees in storms have been mentioned in scientific literature for nearly a century,” the authors write. “Until now, however, crowns had never been directly observed, their behavior described, their UV emissions quantified and their relationship to current demonstrated.”
This gap is relevant because crowns are not mere curiosity. One of its potentially most significant effects is the production of hydroxyl radicalsreactive molecules that act as the main chemical cleaning agents of the atmosphere, decomposing pollutants and natural gases released by trees.
Previous laboratory and modeling work by members of the same research team estimated that crowns around a single canopy during a storm could generate these molecules at a rate at least a thousand times higher to that of all other known production mechanisms in the vicinity of this canopy, considered together.
Laboratory experiments also showed that the thin tips of leaves exposed to electrical fields similar to those found under real thunderstorms became visibly scorched in seconds.
Whether this type of damage accumulates significantly in real forests over time remains an open question, but in regions where storms are frequent, researchers suspect that repeated exposure to crowns could gradually damage the upper branches of the crowns in ways that until now had not been attributed to any cause.
There is still the burning bush issue. Researchers have previously proposed that wreaths constitute a plausible scientific explanation for the Biblical account of a bush that glowed without burning. Regardless of whether or not that specific fire was electrical in nature, the image is suitable.
Forests can harbor your own version of that show during big storms — the treetops silently illuminated by a light no one knew existed, reshaping the chemistry of the air, marking the leaves, and doing it all completely in secret.
