抄録
There are difficulties at present in accepting the theory that ELF sferics are mainly excited by cloud-to-ground discharges. Some discrepancies between theory and experiment are discussed. A new approach to the analysis of the frequency content of intra-cloud and cloud-to-ground discharges is taken by Fourier integrating the whole discharge. It is shown that the current-moment spectrum of the average intra-cloud discharge is approximately an order of magnitude larger than the average cloud-to-ground discharge spectrum in the important ELF sferics range from 10 to-100Hz.
