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Re: [OM] Name that phenomenon

Subject: Re: [OM] Name that phenomenon
From: "Chris Barker" <christopher.barker@xxxxxxxxxxx>
Date: Wed, 10 Nov 1999 17:46:18 +0100
Mirage?

The passage of radio waves by the layers in the atmosphere is called "anomalous
propogation" (anaprop) I believe.

There has to be something to make it worth living in a tube subjected to huge
water pressure... ;-)

Chris

~~ ><>
Chris Barker
Mailto: cmib@xxxxxxxxxxx or mailto: cmib@xxxxxxxxxxxxxxx

----------
>From: Ken Norton <image66@xxxxxxx>
>To: olympus@xxxxxxxxxxxxxxx
>Subject: Re: [OM] Name that phenomenon
>Date: 10 Nov 1999 07:24
>

>>I wonder if there is a name for this phenomenon:
>> http://members.tripod.com/jdubikins/test/test.html
>>It will look a little like the sun at about 10 degrees above the horizon,
>>but it is actually a reflection off the clouds that was quite concentrated
>>and lasted for nearly 10 minutes after sunset was complete.
>
> I'm not sure what the "official term" for this is, but it is just plain old
> refraction.  The cause is nearly identical to the "pools of water" in the
> road ahead of you.  This will happen when there is a layer of air that is
> substantially warmer than another layer.  Light will reflect off the warmer
> layer. This happens quite often in the springtime over large bodies of
> water when the air is much warmer than the water.  At sunset you will get
> the Omega shaped sun and even a complete reflection of the sun up in the
> sky after it has set.  In fact, all sorts of neat stuff happens, like ships
> sailing upsidedown and also you will get to see lights (street lights,
> cars, etc) from 100 miles away.  I've spent hundreds of hours on Lake
> Michigan beaches watching this happen.
>
> BTW, the same thing happens with sound and radio waves.  The rule of thumb
> is that they both refract towards the cooler.  In submarine warfare the
> temperature layers are used for hiding/stealth/stalking purposes.
> Submarines have towed sensor arrays that are dragged in the layers above
> and/or below so they can "hear" what's going on above/below them.  "Piping"
> also occurs and it is possible in one spot in the North Atlantic to hear
> the sound of a bouy chain banging on a rock off of the African coast.  The
> sound got there by crossing the Atlantic towards the carribean and then
> traveling up the gulf stream to this spot near Iceland.  The sound
> signiture was that of a Russian sub less than 600 meters away.  The
> American sub played "cat and mouse" for three days with this phantom sub
> and it took a couple months before the Navy finally figured out what was
> going on.
>
> Ken Norton

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