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Author Topic: Is this a form of 'ducting'?  (Read 402 times)

KE2KB

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Is this a form of 'ducting'?
« on: August 26, 2022, 03:20:44 PM »

A friend once told me that as a kid, while staying at a lake house, he was able to hear normal conversation going on across the lake, about a mile away.
The weather conditions were clear and calm, with a glassy surface on the lake.
This sounds right for the sound waves to be 'ducted' across the lake.
Perhaps there was a temperature inversion just above the surface of the lake, which created the ducting effect.
Or, is this something completely different from ducting of U/VHF radio waves over long distance using low power?
After all, sound waves are not electromagnetic waves; they are percussion waves that can only travel through a medium.

What you think?
Frank <KE2KB>
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GRUMPY2021

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Re: Is this a form of 'ducting'?
« Reply #1 on: August 26, 2022, 04:25:34 PM »

Ducting is exceptional super refraction.  Voices over water amplifies because of refraction so I would say that is a form of ducting.

Interesting read:  https://www.school-for-champions.com/science/sound_amplified_over_water.htm
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AA4PB

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Re: Is this a form of 'ducting'?
« Reply #2 on: August 26, 2022, 04:43:35 PM »

I think it's mostly that sound waves travelling over a smooth lake surface don't experience as much attenuation as it would traveling over land that would have a rough surface, grass, trees, etc.
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Bob  AA4PB
Garrisonville, VA

KC6RWI

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Re: Is this a form of 'ducting'?
« Reply #3 on: August 26, 2022, 07:54:49 PM »

I happened to be thinking about the same thing, the way sound travels,, I am about a mile and half from the freeway, and the sound can be louder some nights and very quiet on other nights. I was going to look it up to see if humidity or temperatures affect the sound.
I do believe I've read of a conditions like what you mentioned.
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K4HB

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Re: Is this a form of 'ducting'?
« Reply #4 on: August 27, 2022, 05:56:19 AM »

Wind also has an effect on sound. The direction it's blowing can result in hearing or not hearing the source.
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K0UA

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Re: Is this a form of 'ducting'?
« Reply #5 on: August 27, 2022, 06:23:31 AM »

In his memoir book "Thunder Below", Submarine Captain Eugene Fluckey (aka luck Fluckey) makes mention of some visual ducting over the ocean at times in the waters near Hokkaido Island.  He spoke of seeing ships hundreds of miles away during certain conditions. This was called "lensing", and while it was a know phenomena it was not very common.
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73  James K0UA

K0RS

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Re: Is this a form of 'ducting'?
« Reply #6 on: August 27, 2022, 10:01:05 AM »

He spoke of seeing ships hundreds of miles away during certain conditions. This was called "lensing", and while it was a know phenomena it was not very common.

I had a very similar thing, on a huge scale, happen to me while traveling in eastern Colorado.  As many know, the eastern 1/3 of the state is geographically more similar to Kansas than the conventional image of Colorado mountainous terrain.  My wife and I crested a rise that afforded a good view back to the west toward the front range, perhaps a hundred miles away.  To our astonishment we saw an entire mountain range where none existed!  It was the Sangre de Cristo range moved much closer and to the north of its actual location.  A truly amazing sight.  In 50 years of living in and traveling this state I've never seen a repeat of this phenomena nor have I ever heard anyone else mention it.  The vision was crisp and clear and quite spooky, making one doubt their senses.
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KC6RWI

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Re: Is this a form of 'ducting'?
« Reply #7 on: August 27, 2022, 03:39:50 PM »

Interesting story, KORS, I wonder if it has to do with some phenomena that makes  distant ships appear to be above the ocean?
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K0UA

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Re: Is this a form of 'ducting'?
« Reply #8 on: August 27, 2022, 03:44:26 PM »

Interesting story, KORS, I wonder if it has to do with some phenomena that makes  distant ships appear to be above the ocean?

I think it is the same thing.
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73  James K0UA

WA3SKN

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Re: Is this a form of 'ducting'?
« Reply #9 on: August 28, 2022, 10:35:31 AM »

It can happen.
Different medium, but same theory.

-Mike.
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KE2KB

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Re: Is this a form of 'ducting'?
« Reply #10 on: August 30, 2022, 02:20:05 PM »

Thanks for sharing your interesting phenomenal accounts;
and I thought V/UHF ducting was exciting!
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KC8KTN

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Re: Is this a form of 'ducting'?
« Reply #11 on: August 30, 2022, 03:54:18 PM »

Is this like skip on 38 LSB
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W0BKR

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Re: Is this a form of 'ducting'?
« Reply #12 on: September 01, 2022, 05:57:17 AM »

No so unusual, surfaces, ambient sounds in the immediate area, etc.

Check this out (well know fact)

https://capitol.mo.gov/1272-2/

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KC8KTN

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Re: Is this a form of 'ducting'?
« Reply #13 on: September 06, 2022, 09:22:03 PM »

I wonder why a post is just taken down.  Wow.
Not locked after several pages. Just taken down...
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