Observations in 2017

Joachim Köppen Kiel 2018

Click on blue-rimmed images to enlarge.

On Oct. 15th, 2017 at the beach of the Baltic Sea, all types of emissions could be heard: When I started listening at about CEST 15:00, I heard apart from the ever-present spherics and the strong clicks (every 1.2 seconds) from an electric fence which was guarding a flock of sheep ... something unusual: There were musical tones rising in frequency, resembling the chirping of birds. After a while it became obvious that these tones were not break-through music from the radio program of the strong AM transmitter at Kalundborg...
These are risers, part of chorus emission:

listen to the sound file

Here is one riser in more detail. Fortunately it occurred well in between two loud clicks from the sheep fence:

listen to the sound file

Later, after CEST 16:55, with the approaching dawn, tweeks appeared in great numbers and strength. By this time, I was well away from the sheep fence.

listen to the sound file

Also, several multi-component whistlers could be heard:

listen to the sound file

Since the frequency of a whistler decreases roughly like the square root of the time after its start, a plot with a logarithmic frequency scale should give nearly straight lines. One sees that this is not quite the case:

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last update: Apr 2018 J.Köppen