T.E.D.D. (Tornado Electrical Discharge Detection) is a public project to gather and publish RF (Radio Frequency) signals produced by tornadoes to help create additional warning and research instrumentation.
Theory
T.E.D.D. is based on the theory that all tornadoes, strong or weak, create a RF (Radio Frequency) footprint or "signature". These RF signatures are believed to be created during the formation and life cycle of a tornado, due to tiny and mass amounts of electrical discharges taking place within the funnel.
Although the exact origin of RF emissions from a tornado remains uncertain, there are several credible scientific sources and publications citing evidence of their existence.
One theory explains that the formation of electrical discharges occur when negatively charged condensation from a severe thunderstorm is drawn down within the tornado's funnel, where it then meets positive charges from the ground. When these opposite charges meet, electrical potential is released along with RF emissions that can be detected using tuned equipment.
Currently, research is being conducted by T.E.D.D. and others to gather more information on this phenomenon.