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From: PeterO <rebyl_kayak_at_iprimus.com.au>
subject: [Paddlewise] Sloping sea illusion?
Date: Thu, 29 Nov 2001 08:31:49 +1100
Dana wrote:
>I have however noticed, from land that the local inland
>sea, Lake Superior, can appear to be higher than the land.

Sid Taylor wrote:
>The entire ocean seemed to tilt. Finally the sea began
>to swirl its way back into the hole which seemed to fill
>reluctantly.

G'Day,
	Thats four of us who have reported similar effects. (I had one reply also
back channel). Dana sounds as though his observation was a land based mirror
of the illusion seen from the sea. I've not seen the swirling effect Sid
mentions but his description of the ocean seeming to tilt is right on the
button. Maybe its caused by a local variation in refractive index of air a
few meters above the sea surface. Line diagrams suggest it might be, but
would water laden air cause enough change to explain the illusion?

All the best, PeterO

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From: Michael Daly <michaeldaly_at_rogers.com>
subject: Re: [Paddlewise] Sloping sea illusion?
Date: Wed, 28 Nov 2001 17:34:37 -0500
From: "PeterO" <rebyl_kayak_at_iprimus.com.au>

> Maybe its caused by a local variation in refractive index of air a
> few meters above the sea surface. Line diagrams suggest it might be, but
> would water laden air cause enough change to explain the illusion?

The first thing I though of was refraction.  The refraction may be a temperature,
rather than humidity, effect.   Hot land, cool water - air temp low near the surface
and increasing with height.  Thermally caused refraction causes mirages and 
that's just a bending-around-the-horizon sort of thing, as your experience is.  
I think refraction and vertigo-like effects on balance organs would be the first
two likely candidates.

Mike


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