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 | Phenomenon | Atmosphere acts like a | GF type | Observer is |
|---|---|---|---|---|
| 1 | “normal” refraction | prism or wedge | “textbook” | anywhere |
| looming and sinking | prism | |||
| towering and stooping | weak lens | |||
| 2 | inferior mirage | strong lens or curved mirror | inf.-mir. | anywhere |
| superior mirage | duct-edge | below inversion | ||
| 3 | “late” mirage | strong lens | none | below inversion |
| 3-image mirage | none | below 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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