The association of sferics with tropical cyclones

Sferic activity associated with six tropical cyclones that occurred in the 1957 to 1958 tropical cyclone season has been investigated. It was found that sferic activity preceded the detection of five out of six of these cyclones and that the sferic distribution and intensity varied with the different stages of cyclone life. When a cyclone rapidly deepened there was an almost complete absence of sferic reports whereas in the last 24 hours of cyclone life sferic activity increased and was closer to the cyclone centre with the greatest sferic activity ahead of the filling cyclone. During the rest of the cyclone life, the sferics were for the most part at distances of from 300 to 400 miles from the cyclone centre with a minimum of sferic activity ahead of the cyclone.