How to Read a Schumann Resonance Spectrogram

It's Simpler Than It Looks

Spectrograms intimidate people. All those colors, no obvious labels, and the one time you tried to read one, someone on Reddit told you that you were wrong. Fair.

But a Schumann spectrogram is really just a heat map with three variables: time, frequency, and intensity. Once you know where each lives, you can read electromagnetic weather in about five seconds flat.

The Axes

Horizontal = time. Left is older, right is newer. Most Schumann spectrograms cover between 8 hours and 3 days. The Tomsk spectrogram on our dashboard shows roughly 3 days. If the right edge is black, that's not "calm" — it's a data gap where the image was recently regenerated.

Vertical = frequency. Bottom is 0 Hz, top is 40 Hz. The Schumann harmonics live at specific heights: 7.83 Hz near the bottom, then 14.3, 20.8, 27.3, and 33.8 Hz stacking up from there.

Color = intensity. Dark blue or black = quiet. Green = moderate. Yellow/orange = elevated. Red/white = something's really happening. This is the dimension that tells you how "loud" the electromagnetic environment is at any given frequency and time.

The Five Bands

Band 1 (6-10 Hz): Where the action starts

The fundamental. Almost always visible as at least a faint horizontal trace at 7.83 Hz. When this band brightens and thickens, conditions are changing. A shift upward in frequency — the bright spot moving higher on the vertical axis — means the ionosphere is being compressed, usually by solar wind. This is the band most people look at first, and it's a reasonable instinct.

Band 2 (10-16 Hz): The reliable second harmonic

Usually the next most visible line, sitting at 14.3 Hz. During quiet times: thin, steady, faint. During active times: brighter, wider, sometimes with extra peaks at unusual frequencies like 12 Hz. Those non-standard peaks are anomalies — your AI analysis flags them, and they tend to indicate unusual electromagnetic excitation.

Band 3 (16-22 Hz): The confirmation band

Fainter during quiet conditions. When band 3 lights up alongside 1 and 2, you're looking at multi-band excitation — a sign of genuine widespread activity, not local noise. If only one band is active, it might be nothing. If three are active simultaneously, something real is going on.

Band 4 (22-30 Hz): The storm indicator

The fourth harmonic at 27.3 Hz is usually invisible during calm periods. Seeing it clearly means the electromagnetic environment is being driven hard. Activity here combined with bands 3 and 5 is the signature of a major geomagnetic event.

Band 5 (30-40 Hz): The rare one

Fifth harmonic at 33.8 Hz. Quiet most of the time. When it lights up, conditions are unusual enough to be worth noting. A spectrogram with all five bands active simultaneously is showing you a significant electromagnetic event — the kind that happens a few times a month during solar maximum and much less often during minimum.

Common Patterns

What does calm look like?

Dark background. Thin, steady lines at the harmonic frequencies. No bright spots. No vertical streaks. The visual equivalent of a flat line on a heart monitor — present but uneventful.

What does elevated look like?

One or two bands glowing green. Lines slightly thicker than usual. The background between harmonics stays mostly dark. This is everyday variation — completely normal, driven by lightning patterns and minor geomagnetic shifts.

What does active look like?

Multiple bands bright. Green, yellow, maybe some orange. Lines are thick and may show brightness at non-standard frequencies. You might see vertical streaks — bursts of broadband energy that cut across all the bands simultaneously. The spectrogram is telling you that several things are happening at once.

What does storm look like?

You won't need this guide to identify a storm spectrogram. Red and white everywhere. The distinct harmonic lines disappear into a wash of broadband activity. Vertical bright columns dominate. It looks dramatically different from anything else — like the difference between a calm lake and a rough sea.

What about the black areas?

If the right edge of the spectrogram is black or empty, that's a data gap. The image was recently regenerated and the newest section hasn't been filled yet. Our AI knows to look at the data just before the gap instead. Don't mistake data gaps for calm periods — they're just missing data.

What are those bright vertical columns?

Sudden geomagnetic impulses. Solar wind pressure spikes hitting the magnetosphere and sending energy across all frequencies at once. Brief, dramatic, and a reliable sign that the solar-terrestrial connection is active. Think of them as electromagnetic thunder.

The Fastest Way to Learn

Check the SunGeo Dashboard daily and compare what you see on the spectrogram with our AI-generated status and score. After a week or two, you'll start recognizing patterns without needing to think about it. After a month, you'll glance at a spectrogram and know the status before reading the text.