Scientists Capture First Direct Evidence of Electric Corona Discharges on Tree Leaves During Storms

The scientific community has finally obtained the first direct field confirmation of a subtle electrical phenomenon known as a corona discharge, which originates from the tips of leaves during periods of intense thunderstorm activity. For decades, this occurrence remained a subject of theoretical modeling and controlled laboratory observations, but it was not until the summer of 2024 that it was successfully documented within a natural environment.

A research team led by meteorologist Patrick McFarland from Pennsylvania State University captured this phenomenon, marking a significant milestone in our understanding of the complex interactions between atmospheric electricity and the Earth's biosphere. The primary field monitoring was conducted in Pembroke, North Carolina, with further evidence gathered by tracking storm systems as they migrated from Florida through to Pennsylvania. To witness these discharges, which are far too faint for the human eye to detect, the researchers utilized a specialized mobile laboratory equipped with sensitive electric field sensors and an ultraviolet (UV) camera mounted on a periscope.

The underlying mechanism of this phenomenon involves the buildup of intense atmospheric electrical energy, which induces an opposing charge in the ground. This terrestrial charge then travels upward toward the highest available points, specifically the sharp extremities of leaves. The team's success relied heavily on the UV camera, which was calibrated to detect radiation within the 255 to 273 nanometer range. Analysis of the video data recorded during active storms showed clusters of UV flashes that were perfectly synchronized with the movement of tree branches. During one 90-minute observation window, the scientists recorded 41 individual corona discharges from leaf tips, with some lasting for as long as three seconds.

The findings of this study were published in the journal Geophysical Research Letters in early 2026, resolving a long-standing scientific puzzle that had previously relied on indirect data regarding electric field anomalies in forested areas. Patrick McFarland emphasized the significance of the discovery, stating: "These things actually happen; we’ve seen them; now we know they exist." Laboratory experiments dating back to the mid-20th century had already indicated that these types of discharges could result in physical burns on leaf tips, potentially damaging cellular membranes and chloroplasts, which negatively impacts the process of photosynthesis.

From an ecological standpoint, the long-term impact of this repeated electrical stress on the health of forest canopies and broader ecosystems remains an open question. Researchers suggest that frequent exposure to these discharges could potentially damage the leaf's cuticle, which serves as a protective waxy barrier. Furthermore, previous studies by scientists at Pennsylvania State University have demonstrated that corona discharges generate hydroxyl (OH) and hydroperoxyl (HO2) radicals. These molecules are known to influence air quality by neutralizing certain greenhouse gases, though they also play a role in the formation of ozone.

Given that approximately two trillion trees grow in regions with a high probability of thunderstorms, and with roughly 1,800 storms occurring globally at any given time, the persistent nature of this phenomenon highlights its potential importance for atmospheric chemistry. The discovery suggests that the electrical dialogue between the sky and the forest is a constant and influential factor in the natural world, warranting further study into how these microscopic sparks affect the global environment over time.