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    Re: Extremely poor conditions??
    From: Brendan Kinch
    Date: 2012 Mar 20, 15:58 +0100

    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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