Schumann resonances occur because the space between the surface of the Earth and the conductive ionosphere acts as a closed waveguide. The limited dimensions of the Earth cause this waveguide to act as a resonant cavity for electromagnetic waves in the ELF band. The cavity is naturally excited by electric currents in lightning. Schumann resonances are the principal background in the electromagnetic spectrum[1] beginning at 3 Hz and extend to 60 Hz,[2] and appear as distinct peaks at extremely low frequencies (ELF) around 7.83 (fundamental),[3] 14.3, 20.8, 27.3 and 33.8 Hz.[1][4]

[link to en.wikipedia.org]

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Alpha waves are neural oscillations in the frequency range of 7.5-12.5 Hz[1] arising from synchronous and coherent (in phase or constructive) electrical activity of thalamic pacemaker cells in humans. They are also called Berger's wave in memory of the founder of EEG.

[link to en.wikipedia.org]

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