World Wide Lightning Location Network

University of Washington in Seattle operating a network of lightning location sensors at VLF (3-30 kHz). Most ground-based observations in the VLF band are dominated by impulsive signals from lightning discharges called “sferics”. Significant radiated electromagnetic power exists from a few hertz to several hundred megahertz, with the bulk of the energy radiated at VLF.

"With our network of sferic sensors we are producing regular maps of lightning activity over the entire Earth. Our map showing the entire world uses coloured spots to indicate lightning strokes (red stars inside an open circle are active WWLLN lightning sensor locations). Click on the map for explanation."