Simultaneous Measurements of Low-Frequency Natural Electric Field at Two Neighbouring Stations

The electromagnetic eigenmodes of Earth-ionosphere global resonator known as Schumann Resonances (SR) are excited by global lightning activity. The simultaneous measurements of electric field in the ELF (~5 - 100 Hz) frequency band at two observatories clearly reveal the global character of the resonator response to the excitation both in the permanent Schumann background as well as in isolated events (transients). It is shown that measurement of ELF electric field can be done with relatively simple equipment.