QRN?

Not sure what's going on here... This would be a spectrum image (30m) from essentially dc to just beyond 5kHz.

We see RTTY, PSK31 and WSPR (at about 2.7kHz). And, we see two strange noisy snakes, about 500Hz apart. Any idea what that could be?

Half of the image was taken with the aerial (rockloop) pointing North-South, during second half of that spectrum scan, the aerial was pointing East-West.

QRN, nature transmits on 30m

Here's some stuff one can observe when no AGC interferes and the risk of a lightning hitting the (indoors) aerial is minimal. Actual I am reminded now that I had intentions to build some meteorological receivers...

Thunderstorm

This spectrum-image nicely shows the storm passing with a maximum intensity. Traces of QRSS signals in this spectrum.

Black clouds passing

These structures were seen in my spectrum receiver earlier. Honestly, they remained a mystery to me. That changed with today's observation however.

Sitting at my study's desk doing paperwork, the sky got extremely dark all of a sudden. Usually I have half an eye on the spectrum receivers, also today, with not much going on. Besides this:

In order to be able to compare the atmospheric stuff with man made signals, I temporarily changed SpectrumLab's settings to cover the 30m WSPR band. To me this result clearly shows that I am not looking at an ionospheric phenomenon.

The plan for the next front transient is to capture even wider spectra.