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    Re: Extremely poor conditions??
    From: John Huth
    Date: 2012 Mar 20, 15:12 +0100
    Then I don't have a good explanation.   Normally you get the kind of curvature you speak of when the surface is hot and the air right at the surface is hot, but the air further above is cool - that's the hot road mirage.   I would expect the opposite effect for those conditions, so I don't have a good explanation in that case. 

    Here's a great website on atmospheric refraction - perhaps you might want to look through it - 

    http://mintaka.sdsu.edu/GF/mirages/mirintro.html


    On Tue, Mar 20, 2012 at 2:53 PM, Alexandre E Eremenko <eremenko---.edu> wrote:

    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.







    --
    Keeping up with the grind
       
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