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Alex wrote: ' In our case, the refraction had to be in the opposite
direction: the ray had to be curved on the opposite direction to the Earth
surface.'

What you describe here is Sub Refraction as opposed to Super refraction.
Sub refraction (is upward bending) and as per Mariners Handbook:  "can occur
when cool air flows over a relatively warmer sea"


Just going out the door right now - can send some more on this if you wish
later.


Kinch.



-----Original Message-----
From: navlist-bounce@fer3.com [mailto:navlist-bounce@fer3.com] On
Behalf Of Alexandre E Eremenko
Sent: 20 March 2012 14:53
To: NavList@fer3.com
Subject: [NavList] Re: Extremely poor conditions??


John,

> I've heard of a report of some very impressive looming over Lake Michigan
> in the spring.   I recall that people in a town in Michigan could see the
> lights of Milwaukee one night - 80 miles away and well over the
> geographic horizon.

But this is "normal refraction", I mean very large, but "in the normal
direction": The light ray is curved in the same direction as the Earth
surface. This sort of refraction would require NEGATIVE correction to
compensate it. In our case, the refraction had to be in the opposite
direction: the ray had to be curved on the opposite direction to the Earth
surface.

This means that the remote toll bioldings whose tops are normally visible
would be unvisible in these conditions.

Alex.

   

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