Live Schumann spectrogram — the Tomsk reading room

How to read the spectrogram

It is a triple map of color, frequency and time. Each horizontal line corresponds to a Schumann mode; when the lines brighten, global lightning is exciting the cavity more strongly.

The brightest strip at the very bottom is mode I — the fundamental resonance near 7.83 hertz. Above it come mode II (14.3), III (20.8), IV (27.3) and V (33.8); going up, the traces weaken and fragment. The vertical position of the lines is fixed; brightness changes with instantaneous amplitude. A common mistake is to read the chart as “the frequency is changing” — what changes is energy, not the frequency itself.

The horizontal axis carries the rhythm of the day: the African lightning sector peaks between UTC 12–18, the Asian sector around UTC 06–10, and the American sector between UTC 21–03. The circulation of these three peaks gives the chart its repeating daily texture. Major storm systems leave broad vertical bands that light up the whole band at once.

What do the colors say?

Dark ground means low amplitude; bright yellow-white regions mean high amplitude. Intermediate purple-red tones mark quiet moments when the signal sits near the noise floor. During the Siberian local night, human-made interference drops and the lower lines usually appear cleaner and better resolved. Sudden horizontal scratches are usually local interference; the global signal always speaks in slow textures.

Why Tomsk?

Tomsk sits in the latitude band where 7.83 hertz is observed most clearly, and it is one of the few major stations that publish their data openly. It stands hundreds of kilometers from the city, almost entirely free of the power grid’s ELF interference. The image on this site is fetched directly from the station’s server and shown without any modification. When the source is down, this page says so honestly — it never shows a fake frame.

If you have come to watch the chart with your own eyes, build a good habit: look at the same time every day. That way you learn its daily rhythm and catch unusual brightness immediately. For what the modes mean see the modes page , and for how the station works see the stations guide .