The Schumann Resonance, traditionally thought of as 7.83 Hz and named after it’s discoverer Winfried Otto Schumann The above picture is today’s recording of Schumann resonances. As you can see the thickest line is right over 7.83. But what about the thin, but defined line at 25 Hz; well, that’s the third order harmonic of the main resonance, but according to wikipedia that line should be at 20.3 Hz
Diagram of Schumann resonances in Earth’s atmosphere
The Schumann resonances (SR) are a set of spectrum peaks in the extremely low frequency (ELF) portion of the Earth‘s electromagnetic field spectrum. Schumann resonances are global electromagnetic resonances, generated and excited by lightning discharges in the cavity formed by the Earth’s surface and the ionosphere.
sosrff.tsu.ru –Real-time Schumann Resonance Meter located in Tomsk, Russia.