Thunderstorms have long been known to generate electrical discharges on plants below them, potentially igniting weak sparks at the tips of leaves and along branches. This phenomenon, called coronae, had never been observed in nature until a recent study shed light on this mysterious occurrence.
Published in Geophysical Research Letters, the study unveiled how the tips of tree leaves can burn with ghostly ultraviolet sparks during thunderstorms. Lead author Patrick McFarland, a meteorologist at The Pennsylvania State University, expressed his excitement over finally witnessing these coronae in the wild. He stated, “These things actually happen; we’ve seen them; we know they exist now.”
Prior to this groundbreaking study, scientists had only observed coronae forming in laboratory settings. McFarland described how, in a controlled environment, these coronae appear as a faint blue glow. This led researchers to theorize that the electrical charge from a thunderstorm overhead induces an opposing charge on the ground, attracting the opposing charge to the highest points it can reach – the tree canopy. As a result, the tips of leaves discharge electricity, creating blue sparks or coronae.
To capture these elusive coronae in nature, McFarland and his team outfitted a Toyota Sienna with a mobile weather station equipped with an ultraviolet camera. They embarked on storm-chasing expeditions, recording videos of the phenomena as they occurred. Analysis of the footage confirmed the presence of coronae, glowing on the tips of tree leaves and even jumping from leaf to leaf.
If humans could perceive ultraviolet light, McFarland speculated that the entire tree canopy would appear aglow, resembling a spectacular light show. He likened it to a scene where thousands of UV-flashing fireflies descended upon the treetops.
The study’s findings not only provide valuable insights into the interaction between thunderstorms and forests but also underscore the importance of scientific exploration in understanding the natural world. The discovery of coronae in nature opens up new avenues for research and underscores the beauty and complexity of our environment.
