Trees release invisible electric sparks during thunderstorms, a phenomenon that has been observed for the first time by scientists. These sparks, known as corona discharges, are nearly invisible electrical leaks that can alter leaf surfaces and nudge local air chemistry. Using a van-mounted ultraviolet telescope, researchers tracked bursts of corona discharge hopping across leaf tips as storms passed overhead. The study, published in Geophysical Research Letters, reveals that entire canopies can leak tiny currents into the air, challenging the notion that lightning is the only electrical force touching the forest canopy. The research, conducted by meteorologist Patrick McFarland at Penn State, recorded repeated flashes across multiple storms and tree species, suggesting this quiet exchange between sky and canopy may be more common than once thought. The electrical sparks appear as faint glows, far weaker than lightning, and can last up to three seconds. These sparks are difficult to measure due to the constant motion of leaves caused by storm winds, which can redirect current to new edges. The study also highlights the potential impact of corona on air chemistry, as electrical charge can spark the formation of reactive chemicals, boosting levels of the hydroxyl radical and breaking down natural gases released by leaves. The research changes how scientists think about storm-forest interactions, showing that trees and weather connect through more than lightning, and that a once-hidden electrical process can now be measured directly to improve tree-health studies and local air models.
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