The first proof that treetops really glow<\/h2>\n\n\n\n
During a thunderstorm in Pembroke, North Carolina, the team aimed an ultraviolet-sensitive camera at three branches of a sweetgum tree and later identified 41 distinct corona events in about 90 minutes. Each flicker lasted up to 3 seconds, and the signals often hopped from leaf to leaf as branches swayed in the wind.<\/p>\n\n\n\n
Penn State\u2019s account suggests the full count can be much larger when you include every detectable event, with 859 coronae on the sweetgum and 93 on a nearby loblolly pine during that same storm. Researchers also reported similar activity under additional thunderstorms as they traveled between Florida and Pennsylvania in the summer of 2024.<\/p>\n\n\n\n
Read More: Jumbo is recalling 14- and 28-ounce bags of frozen green beans after several customers reported a discovery that was as disgusting as it was unsettling<\/a><\/h3>\n<\/div>\n<\/div><\/div>\n<\/div>\n\n\n\nIf humans could see ultraviolet light, McFarland says the treetops would look like \u201cthousands of UV flashing fireflies\u201d arriving all at once. It is a vivid image, but it marks a shift \u2013 something long suspected in labs has now been recorded outdoors.<\/p>\n\n\n\n
A weather phenomenon called a \u201ccorona\u201d<\/h2>\n\n\n\n
A corona discharge<\/a> is a weak electrical leak into the air that forms around sharp points when the electric field gets strong enough. It belongs to the same family of effects as Saint Elmo\u2019s fire, a bluish glow sailors sometimes reported on ship masts during storms.<\/p>\n\n\n\nIn practical terms, a thundercloud can build up a strong charge that pulls an opposite charge up from the ground below. In a forest, that rising charge funnels through trunks and branches until it concentrates at leaf tips and needles, where it can spark a faint blue glow and a burst of ultraviolet.<\/p>\n\n\n\n![\"Tree](\"https:\/\/www.ecoticias.com\/en\/wp-content\/uploads\/2026\/04\/tree-needles-ultraviolet-corona-discharge-thunderstorm.jpg\" "\\"\\"")
Purple corona discharges appear at the tips of tree needles, showing the hidden electrical flashes researchers detected during storms.<\/figcaption><\/figure>\n\n\n\nIn the lab, researchers can barely see that glow when the room is darkened, but outdoors it is drowned out even under a stormy sky. That is why the field team leaned on ultraviolet measurements, which act like a fingerprint for coronae when your eyes cannot do the job.<\/p>\n\n\n\n
The minivan that chased thunderstorms<\/h2>\n\n\n\n
To catch something so subtle, the researchers turned a 2013 Toyota Sienna into a rolling storm lab with a weather station, an electric field detector, and a laser rangefinder. They also mounted a periscope-style system feeding light into an ultraviolet camera, after cutting a hole about 12 inches wide through the roof.<\/p>\n\n\n\n
They started in Florida, betting on frequent summer storms, but many cells fizzled quickly. On the way back north, the team set up near the University of North Carolina at Pembroke and trained their instruments on trees about 100 feet away while lightning<\/a> flashed and rain fell for nearly two hours.<\/p>\n\n\n\nPenn State calls the setup the Corona Observing Telescope System, essentially a telescope paired with a UV camera and calibrated for ultraviolet emissions. The system blocks the solar UV band, leaving only a few possible sources in the recordings: coronae, lightning, and fire.<\/p>\n\n\n\n
What this could mean for forests<\/h2>\n\n\n\n
These observations matter because coronae are not just \u201cpretty\u201d physics \u2013 they can affect plant tissue. The AGU press release notes that coronae can leave leaf tips visibly burnt within seconds, and lab work suggests the discharges may damage the cuticle, the waxy layer that helps leaves resist dehydration and UV stress.<\/p>\n\n\n\n
One corona does not seem to do much harm by itself, but storms do not happen only once. Researchers speculate that repeated events across a canopy could add up, which is why they want forest ecologists and botanists involved next.<\/p>\n\n\n\n
\n\n\nRead More: Cannibalism is decimating blue crab larvae, but shallow waters still offer them a chance<\/a><\/h3>\n<\/div>\n<\/div><\/div>\n<\/div>\n\n\n\nFor ecologists, the unanswered questions are the point. Do these flashes measurably affect photosynthesis or growth, or do trees shrug them off as minor wear and tear from thunderstorm season?<\/p>\n\n\n\n
A possible link to cleaner air and greenhouse gases<\/h2>\n\n\n\n
The story is not only about trees \u2013 it is also about the air swirling through the branches. Penn State researchers explain that ultraviolet light from coronae can break apart water vapor, producing hydroxyl<\/a>, a highly reactive molecule often called the atmosphere\u2019s main \u201ccleanser.\u201d<\/p>\n\n\n\nHydroxyl reacts with many chemicals, including volatile organic compounds released by trees and methane, a potent greenhouse gas<\/a>, turning them into forms that are easier for the atmosphere to remove. The Penn State release points to the group\u2019s earlier work suggesting corona discharges in forest canopies can be a substantial source of these oxidizing chemicals.<\/p>\n\n\n\n\n\n\nRead More: For more than a century, the ocean has prevented a severe global drought, but almost no one has described it that way<\/a><\/h3>\n<\/div>\n<\/div><\/div>\n<\/div>\n\n\n\nIf coronae are widespread during storms, they could briefly boost this chemical \u201cscrubbing\u201d in and above forests when thunderheads roll through. But the scale, and whether it meaningfully changes regional air quality<\/a> or climate-relevant chemistry, is still uncertain.<\/p>\n\n\n\nWhat researchers want to learn next<\/h2>\n\n\n\n
Now that coronae on wild trees have been documented, the next step is figuring out how common they are and under what conditions they spike. In practical terms, that likely means more field campaigns that pair storm electricity measurements with careful tree biology<\/a>.<\/p>\n\n\n\nThere is also a measurement angle \u2013 lab tests found the ultraviolet emission from coronae scales with the electrical current measured in the tree. If that relationship holds widely outdoors, ultraviolet cameras could become a new way to map storm-driven electrical currents moving through forest canopies.<\/p>\n\n\n\n
Next time a summer storm turns the sky dark, it is worth remembering that the treetops may be shimmering in a spectrum we cannot see. <\/p>\n\n\n\n
The study was published in Geophysical Research Letters<\/em><\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"Thunderstorms already have a lot going on. Now researchers say there is another layer to the chaos, a nearly invisible … <\/p>\n
In practical terms, a thundercloud can build up a strong charge that pulls an opposite charge up from the ground below. In a forest, that rising charge funnels through trunks and branches until it concentrates at leaf tips and needles, where it can spark a faint blue glow and a burst of ultraviolet.<\/p>\n\n\n\n In the lab, researchers can barely see that glow when the room is darkened, but outdoors it is drowned out even under a stormy sky. That is why the field team leaned on ultraviolet measurements, which act like a fingerprint for coronae when your eyes cannot do the job.<\/p>\n\n\n\n To catch something so subtle, the researchers turned a 2013 Toyota Sienna into a rolling storm lab with a weather station, an electric field detector, and a laser rangefinder. They also mounted a periscope-style system feeding light into an ultraviolet camera, after cutting a hole about 12 inches wide through the roof.<\/p>\n\n\n\n They started in Florida, betting on frequent summer storms, but many cells fizzled quickly. On the way back north, the team set up near the University of North Carolina at Pembroke and trained their instruments on trees about 100 feet away while lightning<\/a> flashed and rain fell for nearly two hours.<\/p>\n\n\n\n Penn State calls the setup the Corona Observing Telescope System, essentially a telescope paired with a UV camera and calibrated for ultraviolet emissions. The system blocks the solar UV band, leaving only a few possible sources in the recordings: coronae, lightning, and fire.<\/p>\n\n\n\n These observations matter because coronae are not just \u201cpretty\u201d physics \u2013 they can affect plant tissue. The AGU press release notes that coronae can leave leaf tips visibly burnt within seconds, and lab work suggests the discharges may damage the cuticle, the waxy layer that helps leaves resist dehydration and UV stress.<\/p>\n\n\n\n One corona does not seem to do much harm by itself, but storms do not happen only once. Researchers speculate that repeated events across a canopy could add up, which is why they want forest ecologists and botanists involved next.<\/p>\n\n\n\n For ecologists, the unanswered questions are the point. Do these flashes measurably affect photosynthesis or growth, or do trees shrug them off as minor wear and tear from thunderstorm season?<\/p>\n\n\n\n The story is not only about trees \u2013 it is also about the air swirling through the branches. Penn State researchers explain that ultraviolet light from coronae can break apart water vapor, producing hydroxyl<\/a>, a highly reactive molecule often called the atmosphere\u2019s main \u201ccleanser.\u201d<\/p>\n\n\n\n Hydroxyl reacts with many chemicals, including volatile organic compounds released by trees and methane, a potent greenhouse gas<\/a>, turning them into forms that are easier for the atmosphere to remove. The Penn State release points to the group\u2019s earlier work suggesting corona discharges in forest canopies can be a substantial source of these oxidizing chemicals.<\/p>\n\n\n\n If coronae are widespread during storms, they could briefly boost this chemical \u201cscrubbing\u201d in and above forests when thunderheads roll through. But the scale, and whether it meaningfully changes regional air quality<\/a> or climate-relevant chemistry, is still uncertain.<\/p>\n\n\n\n Now that coronae on wild trees have been documented, the next step is figuring out how common they are and under what conditions they spike. In practical terms, that likely means more field campaigns that pair storm electricity measurements with careful tree biology<\/a>.<\/p>\n\n\n\n There is also a measurement angle \u2013 lab tests found the ultraviolet emission from coronae scales with the electrical current measured in the tree. If that relationship holds widely outdoors, ultraviolet cameras could become a new way to map storm-driven electrical currents moving through forest canopies.<\/p>\n\n\n\n Next time a summer storm turns the sky dark, it is worth remembering that the treetops may be shimmering in a spectrum we cannot see. <\/p>\n\n\n\n The study was published in Geophysical Research Letters<\/em><\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":" Thunderstorms already have a lot going on. Now researchers say there is another layer to the chaos, a nearly invisible … <\/p>\nThe minivan that chased thunderstorms<\/h2>\n\n\n\n
What this could mean for forests<\/h2>\n\n\n\n
Read More: Cannibalism is decimating blue crab larvae, but shallow waters still offer them a chance<\/a><\/h3>\n<\/div>\n<\/div><\/div>\n<\/div>\n\n\n\n
A possible link to cleaner air and greenhouse gases<\/h2>\n\n\n\n
Read More: For more than a century, the ocean has prevented a severe global drought, but almost no one has described it that way<\/a><\/h3>\n<\/div>\n<\/div><\/div>\n<\/div>\n\n\n\n
What researchers want to learn next<\/h2>\n\n\n\n