Spectral parameters of the VLF radio noise observed as functions of the azimuth

The actions of a new atmospherics analyzer, which determines for every incoming atmospheric the apparent angle of arrival together with certain characteristics of the VLF spectrum, are briefly explained. Then the physical significance of the observable spectral quantities are considered by use of a simplified version of the VLF waveguide mode theory. Finally, spectral observations of a 4-week period are presented in such a way that the influence of daytime and azimuth are evident and comparison with theoretical propagation computations is enabled.