TORNADO hunters may have a new ally 鈥� electricity.
Armed with only an antenna and a receiver, Ernst Schmitter of the University of Applied Sciences at Osnabr眉ck in Germany and John Leeman from the Leeman Webb Storm Laboratory in Norman, Oklahoma, picked up low-frequency electromagnetic waves in a rotating storm known as a 鈥渟upercell鈥�. About 30 per cent of these storms spawn tornadoes.
Schmitter and Leeman believe it is the supercell鈥檚 swirling action that generates the signal. When dust particles and droplets within the storm rub against each other, they become oppositely charged. The lighter particles, which are mostly negative, get blown to the top of the funnel, while the heavier, positive ones sink to the bottom. As the separated particles rotate around the vortex, they emit low-frequency electromagnetic radiation (Atmospheric Research, ).
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This will improve tornado detection, which usually relies on teams of spotters and weather radar. Such methods can fall down in poor visibility, or when clouds or heavy rain block the microwaves used in radar. In contrast, low-frequency radiation can penetrate further through cloud and rain than microwaves. What鈥檚 more, an electromagnetic signal could be picked up instantly, whereas it takes time to refresh each radar scan.