The Schumann resonance is a phenomenon of electromagnetic waves oscillating in the Earth's atmospheric cavity with a first harmonic resonant frequency typically around 7.8 Hz.

“example compared to up in in more northern areas but I want to say this is all natural electromagnetic foot print and occasionally the magnetic field has these micro pulsations in the low frequency range it's typically DC which is static so no frequency no oscillations just continuous I mean if it varies throughout the day in terms of intensity but if it does pulsate it's in the low frequency range and then there's this phenomenon called the schumans resonance which a lot of people have heard of which is um electromagnetic waves oscillating in this cavity uh in our atmosphere and that's typically uh resulting in a frequency a resonant frequency of around 7.8 Hertz is the first harmonic and it can vary depending on solar activity and magnetic disturbances and go up to let's say 30 50 hertz maybe off case like a 100 HZ”