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    Mirages, was: Refraction
    From: Trevor Kenchington
    Date: 2004 Jul 12, 08:44 +0000

    An image sunk below the horizon could not be seen and thus could not be
    an image. However, I think what you are getting at is a converse of the
    classic mirage seen in hot, desert areas.
    Low-latitude mirages involve light rays bending upwards very near the
    ground, so that we see light from the sky apparently rising from the
    ground. But high-latitude mirages involve the reverse bend, so that
    surface light appears to come from the sky. They are perhaps most common
    in the form of "ice blink", where sunlight reflected off ice beyond the
    horizon is visible as a whiteness in the sky. However, there are reports
    of people seeing, in the sky, inverted images of ships which, in
    reality, are hull-down over the horizon.
    I have characterized the two types as "low" and "high" latitude but they
    are, of course, respectively the result of (1) intense solar heating of
    a land surface under cooler air and (2) the presence of warmer air
    overlying a very cold surface.
    Trevor Kenchington
    Fred Hebard wrote:
    > OK ladies & gentlemen.  We have the case of a mirage, where the image
    > rises above the desert floor.  Are there any counter examples of an
    > image sinking below the horizon?
    Trevor J. Kenchington PhD                         Gadus@iStar.ca
    Gadus Associates,                                 Office(902) 889-9250
    R.R.#1, Musquodoboit Harbour,                     Fax   (902) 889-9251
    Nova Scotia  B0J 2L0, CANADA                      Home  (902) 889-3555
                         Science Serving the Fisheries

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