Penn State Meteorologists Capture First Photographic Evidence Of Treetop Corona Discharges Producing Atmospheric Cleansers During Storms

Penn State researchers capture the first images of corona discharges on trees. Discover how these glowing leaf tips produce hydroxyl to clean the atmosphere.

By: AXL Media

Published: Apr 18, 2026, 10:40 AM EDT

Source: Information for this report was sourced from EurekAlert!

Documenting A Long Hypothesized Atmospheric Phenomenon

For over 70 years, the scientific community has theorized that the odd electrical activity detected above forests during thunderstorms was caused by corona discharges at the tips of leaves. Until recently, however, this phenomenon had never been observed outside of a laboratory setting. A team of meteorologists and atmospheric scientists from Penn State has finally bridged this gap, capturing the first direct evidence of treetops glowing in the ultraviolet (UV) spectrum during intense weather events. This discovery confirms that trees play an active, electrical role in the complex chemistry of the Earth's atmosphere during storms.

The Physics Of Treetop Electrical Glows

Corona discharges form when the massive negative charges built up within storm clouds attract an equal and opposite positive charge from the ground. As this positive charge rises through the forest, it concentrates at the highest points of the canopy. The intense electric field created at the hair-like tips of leaves becomes strong enough to ionize the surrounding air, resulting in a weak glow in both the visible and ultraviolet ranges. While the visible light is often drowned out by the sun or lightning, the ultraviolet emission is a distinct signature of this energy transfer between the earth and the sky.

The Corona Observing Telescope System

To capture these elusive events, the researchers developed the Corona Observing Telescope System, a specialized Newtonian telescope integrated with a high-sensitivity UV camera. This device was calibrated to block out all solar UV wavelengths, ensuring that any detected light originated only from corona, lightning, or fire. Mounted on a modified van, the system allowed the team to track storms along the U.S. East Coast. Their efforts culminated in North Carolina, where they recorded 859 individual corona events on a 100-foot-tall sweetgum tree and 93 on a nearby loblolly pine.