Wind turbines emit lightning flashes upwards, producing these electrical discharges at regular intervals relative to the turbine's rotation, and can do so tens of kilometres away from an active thunderstorm area.

Joan Montanyà at the Polytechnic University of Catalonia in Terrassa, Spain, and his colleagues plotted radio emissions from lightning strikes detected by a mapping array system installed on the east coast of Spain. Later, a high-speed video was used to capture the flashes (pictured). The authors found that turbine blades send electrical discharges upwards in synchronization with their rotation; these discharge episodes lasted for more than an hour under certain storm conditions. The results confirm that rotating wind turbines can initiate lightning more easily than static objects, the authors say.

Credit: Joan Montanya et al./AGU

J. Geophys. Res. Atmos. (2014)