Re: [Paddlewise] Sloping sea illusion?

I've noticed this illusion in places where the land is almost flat and
sloping gently upward from the water surface.  I attributed it to a
false perception of the land as providing a true horizon and therefore
the water was sloping downward relative to this falsely perceived
horizontal reference.  A similar illusion occurs at the many 'Mystery
Spot' locations where the local topography is sloped in a way that fools
our perception and can make it seem that water is flowing uphill.  Of
course, these sites generally also have deliberately distorted
structures and slanted vegetation to enhance the illusion.

Michael Daly wrote:
> 
> 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.
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