Every second, roughly 40 to 50 lightning bolts strike somewhere on Earth. Each one sends an electromagnetic pulse ringing between the ground and the ionosphere, the charged layer starting about 60 kilometers up. Most of that energy fades instantly. But at a handful of specific frequencies, the waves reinforce each other instead of canceling out, building a standing wave that circles the planet continuously. That standing wave is the 

Schumann resonance — the lowest, steadiest hum in Earth's electromagnetic field, and one of the more searched, and more misunderstood, numbers in this entire wiki.

Earth's surface and the ionosphere form a natural cavity, a shell of conductive layers with a gap of thin, mostly non-conductive atmosphere in between. Electromagnetic waves generated by lightning get trapped in that cavity, bouncing between the two conductive boundaries. At certain wavelengths — ones that fit neatly around the Earth's circumference — the waves interfere constructively and build into a persistent resonance rather than dying out.

The physicist Winfried Otto Schumann predicted this effect mathematically in 1952, and it was measured directly a few years later. It's now one of the standard tools geophysicists use to monitor global lightning activity and the state of the ionosphere from the ground, continuously recorded at observatories around the world.

The fundamental resonance sits at approximately 7.83 Hz, with a series of harmonics above it at roughly 14.3, 20.8, 27.3, and 33.8 Hz. These numbers are remarkably stable — they're set by the physical size of the Earth-ionosphere cavity, which doesn't change on human timescales.

Worth being precise about here: 7.83 Hz is far below the range of human hearing, which starts around 20 Hz, so nobody can actually hear the Schumann resonance, no matter what a recording labeled "7.83 Hz Earth frequency" claims to deliver through headphones. That's worth separating clearly from a different, unrelated category of audible tones — frequencies like 432 Hz, 528 Hz, or various others marketed as "healing frequencies." 

Those are ordinary musical pitches, audible and man-made, based on tuning conventions rather than any measured natural Earth phenomenon, and claims about their specific effects on the brain remain anecdotal rather than scientifically established. They share a marketing vocabulary with the Schumann resonance — "frequency," "resonance," "healing" — but they're a genuinely different topic, not a variation on the real geophysical signal described here.

This is where most online claims about Schumann resonance go wrong. The frequency — where the resonance sits on the spectrum — stays close to 7.83 Hz. What actually varies, sometimes dramatically, is the amplitude: how strong or "loud" the signal is at that frequency, usually shown on spectrograms as brighter colors or saturated white bands.

Claims that the fundamental frequency has permanently "risen" or is "getting higher" year over year describe amplitude spikes and instrument saturation, not an actual shift in the resonant frequency. The cavity's dimensions haven't changed; what changes is how energetically it's being excited. So when someone asks whether the resonance is "spiking right now" or was unusually active "last night," that's a real, answerable, amplitude-based question — unlike whether the frequency itself is rising, which it isn't.

Two things push Schumann amplitude up:

One practical consequence of this: there's no single, universally agreed "high" amplitude threshold the way there's an official Kp-based G-scale for geomagnetic storms. Different monitoring stations use different instruments, calibration, and local noise floors, so a reading that looks dramatic on one station's spectrogram can look modest on another's recorded at the same moment. That's also why accuracy claims about any single live reading deserve a bit of skepticism about precision — the underlying frequency measurement is solid physics, but a specific station's amplitude number on a specific day reflects that station's particular setup as much as global conditions.

This is the part of the topic that gets the most attention and the least scientific certainty. A popular explanation notes that 7.83 Hz sits near the boundary between theta brainwaves (associated with drowsiness and deep meditation) and alpha brainwaves (associated with relaxed alertness), and suggests that amplitude spikes disrupt this natural rhythm — a genuinely interesting hypothesis about "what happens to the body at resonant frequency," though one still more theoretical than confirmed.

There is at least one study that looked directly at this question for blood pressure specifically, rather than the broader geomagnetic-activity research covered elsewhere in this wiki: a Japanese study monitoring ambulatory blood pressure in adults over a week found measurable differences between days of normal versus enhanced Schumann activity, though — consistent with the state of this research generally — it was a small, observational study, and the authors themselves called for further controlled work before drawing firm conclusions.

On animals: broader research has shown fairly convincingly that many species — birds, fish, and others — are sensitive to extremely low-frequency electromagnetic signals in general, which is well-established science covered in this wiki's circadian rhythms entry. Research tying animal behavior specifically to Schumann resonance amplitude, rather than geomagnetic activity more broadly, is considerably thinner, and 7.83 Hz itself isn't inherently harmful in any dose the natural environment produces — it's the ambient electromagnetic backdrop every organism on Earth, humans included, has always lived inside.

What's solid across all of this: many people consistently report headaches, fatigue, disrupted sleep, or difficulty concentrating during periods of high Schumann amplitude, often overlapping with geomagnetic storms. What's not yet established: a proven causal mechanism connecting the two, in humans or animals. The correlation is reported widely enough that self-tracking — noting your own symptoms against the daily amplitude chart — is a reasonable way to see whether the pattern holds for you personally, even while the underlying science remains open, and even while some of the more sweeping spiritual framing that circulates around this topic (planetary "ascension," a fixed target of collective human consciousness) goes well beyond anything the data actually shows.