Observations/Mirage

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Mirage

A mirage is a naturally-occurring optical phenomenon in which light rays bend via refraction to produce a displaced image of distant objects or the sky. The word Mirage comes from the French verb mirer ("to look at"), which is related to mirror. Mirer, itself, is from Latin mīrārī ("to wonder at"), the ancestor of the commonly seen admire, miracle, and marvel.

Mirages have a reputation for deceit. The classic example is the oasis in the desert or the legendary ghost ship, the Flying Dutchman.

"It's not an optical illusion"

Anthony Young, an astronomer at San Diego State University, told Live Science. It's not an optical illusion, that's the thing people get wrong about mirages. The mirage is an image of a real thing — it can even be photographed — but it's often a distorted image, and it's easy to misinterpret.

Inferior Mirage

A schematic of an inferior mirage, showing a) the unrefracted line of sight, b) the refracted line of sight and c) the apparent position of the refracted image.

We’ve all seen in films and cartoons. Someone wandering through a hot desert for days desperate for water, and suddenly, out of nowhere, a shady, watery oasis materializes several hundred yards ahead. With the little bit of strength they have left, they run toward the promise of relief from their intense thirst, only to be sorely disappointed when the vision vanishes as they reach its perceived location.

The inferior mirage is produced when light rays from an object approach a hotter region and are refracted away from the hot area. In the desert, the rays approaching the hot surface are turned upward away from the surface. If those upward rays are intercepted by your eye, you see the mirage image appearing below the actual object

Superior Mirage

A superior mirage of a plane on ice, McMurdo Station

A superior mirage is one in which the mirage image appears to be located above the real object. A superior mirage occurs when the air below the line of sight is colder than the air above it. This unusual arrangement is called a temperature inversion, since warm air above cold air is the opposite of the normal temperature gradient of the atmosphere during the daytime. Passing through the temperature inversion, the light rays are bent down, and so the image appears above the true object, hence the name superior.

Superior mirages are quite common in polar regions, especially over large sheets of ice that have a uniform low temperature. Superior mirages also occur at more moderate latitudes, although in those cases they are weaker and tend to be less smooth and stable. For example, a distant shoreline may appear to tower and look higher (and, thus, perhaps closer) than it really is.

A superior mirage can be right-side up or upside-down, depending on the distance of the true object and the temperature gradient. Often the image appears as a distorted mixture of up and down parts.

Fata Morgana

An optical illusion caused the ship to appear as though it was hovering above the horizon

A Fata Morgana is a type of Superior Mirage that is common in the Arctic, but can appear rarely in the UK during winter.

The name "Fata Morgana" comes from the Italian translation of Morgan le Fay, the fairy, shapeshifting half-sister of King Arthur) is a very complex superior mirage. It appears with alternations of compressed and stretched areas, erect images, and inverted images. A Fata Morgana is also a fast-changing mirage.

Fata Morgana mirages are most common in polar regions, especially over large sheets of ice with a uniform low temperature, but they can be observed almost anywhere. In polar regions, a Fata Morgana may be observed on cold days; in desert areas and over oceans and lakes, a Fata Morgana may be observed on hot days.

Erf's Curve gets flattened?

Take note: According to globe proponents, If the vertical temperature gradient is +12.9 °C (23.2 °F) per 100 meters (330 feet); where the temperature increases at higher altitudes - then horizontal light rays will just follow the "curvature of Earth", and the horizon will appear flat.

Because of this statement it is important when performing optical earth curve tests (like laser tests, mirror flashes, videos), make sure to record the temperatures at ground level and at the observer's height. If the temperature gradient matches the above "globe refraction prediction", a "level" earth result will be immediately criticized. Without temperature readings, it's likely your results will be discarded.

See Also