Atmospheric noises on HF

[RadioDaze]

As we all know we do not always just hear voices on the radio.

I sometimes hear kak...kak....kak...kak... a regular once a second (approx) cracking noise and warbles that seem to descend in frequency.....fizzly noises. Quick yet complex discharge like sounds that last 2 seconds etc. that often repeat and are only audible on 1 frequency. I am sure we all do.

Does anyone have any information or documentation/recordings and discussion about these sounds that we hear and what they are and their probably origins.

I commonly hear sounds like this though slightly longer in duration:

 

[RadioDaze]

I dug a little deeper it might be ones of these:

http://www.hfunderground.com/wiki/Ionogram

 

[RatsoW8]

I've been hearing that particular sound for as long as I've been a ham.. Hearing it on 20m lately because that's where I'm spending most of my time.

 

[222DBFL]

Sounds like conditions are about to change. That is what I normally hear before the dx either starts or changes around to a different area. Other than that it could be just plain old rf energy just letting us know it's there. RF energy is everywhere!!

 

[RadioDaze]

I think I have heard them more in the winter months this side of the pond, the squiggly blips do indeed seem to be Ionosonde's.