Solar X-rays:

Geomagnetic Field:

“The Sferics Timing And Ranging NETwork (STARNET) was initially deployed in 1997  as an experimental network developed by Resolution Display Inc. (RDI) under a NASA Small Business Innovative Research grant. RDI developed a system that consisted of five Very Low Frequency (7-15 kHz) radio receivers to detect sferics that were  situated along the US east coast and Puerto Rico. Sferics is the radio noise  emitted by lightning over a broad region of the electromagnetic spectrum, which  in the VLF band can propagate over thousands of kilometers in the earth-ionosphere  wave-guide.”  From the Starnet web site.

Listen to sample sounds of Sferics (short for Atmospherics) at the NASA site -

“A Radio Atmospheric signal or Sferic is a broadband electromagnetic  impulse that generated by lightning discharges. The bulk of its energy  concentrates within the ELF and VLF bands.”  From the Stanford VLF Group web page - this is a very interesting site with a lot of scientific details on their research and Sferics in general.

A YouTube video about Sferics - watching the waveforms on an osscilloscope...


A YouTube video - watching & listening to Sferics using computer spectrum analysis software...


Monitoring Sferics from an approaching storm in Tennessee - Uploaded on May 25, 2011

“VLF Sferics and ThunderMike Audio  pick up of ambient outdoor sounds as 5-25-2011 storm is approaching  Lebanon, Tenn. Storm was about 100 miles West of Lebanon when lightning  data IMG was snapped and VLF Audio was ripped.”