Atmospheric Refraction Phenomena

Mirages and green flashes, the main topics of this website, are only some of the phenomena caused by refraction in the Earth's atmosphere. To put everything into perspective, here's a list of the main atmospheric refraction phenomena:

Number
of Images
PhenomenonAtmosphere
acts like a
GF typeObserver is
1 normal” refractionprism or wedge textbookanywhere
looming and sinkingprism
towering and stoopingweak lens
2 inferior mirage strong lens or
curved mirror
inf.-mir. anywhere
superior mirage duct-edgebelow inversion
3 “late” miragestrong lens nonebelow inversion
3-image mirage nonebelow inversion
mock mirage mock-mir. above inversion
> 3 5-image mirages;
Fata Morganas
series of lenses none or
duct-edge
within or below
strong inversions

Links in the table lead to simulations; see the glossary for explanations of the various terms.

Note that a display does not count as a “mirage” unless there is at least one inverted image. (It's possible for the inverted image of a simple superior mirage to be the only one visible.)

Note, too, that the standard terminology of geometrical optics makes all erect images “virtual” images, and all inverted images “real.” Erect and inverted images always alternate, though some may be so strongly compressed as to be imperceptible, even with magnification.

In general, none of the erect images is exactly aligned with the geometric position of the object; and all images are astigmatic.

The rare and complex displays in the bottom row of the table are poorly understood.

Copyright © 2002, 2005, 2006, 2009, 2010 Andrew T. Young


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