Anomalously Strong Vertical Magnetic Fields from Distant Lightning

Abstract:

At distances of thousands of kilometers from lightning the vertical component of the magnetic field in the Very Low Frequencies (VLF – 3-30 kHz) and Extremely Low Frequencies (ELF – 3-3000 Hz) is expected to be very weak and several orders of magnitude lower than the horizontal magnetic components. However, measurements in Israel show a relatively strong vertical magnetic component in both the ELF and VLF bands, at the same order of magnitude as the horizontal components. Our measurements suggest that the real Earth-ionosphere waveguide might often be very different from the theoretical waveguide used in model calculations.