The electric radiation fields produced by lightning return strokes, stepped leaders, and intracloud discharge processes have been Fourier-analyzed to determine amplitude spectra for these processes from about 100 kHz to 20 MHz. The fields were recorded under conditions where the field propagation from the lightning ocations were known and where the field propagation from the lightning sources to the recording site was entirely over salt water. The spectra for return stokes show an f-1 frequency dependence from 100 kHz to 2 MHz, an f-2 dependence between 2 and 10 MHz, and an f-5 decrease above 10 MHz. In the 1 to 20 MHz range, the spectra of the initial fast transition in return strokes, the initial fast-rising portion of leader steps and the fast transitions in positive intracloud pulses are suprisingly similar.