Mirage

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Farallon Islands at inferior mirage no mirage and superior mirage

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Mirage-diagram

Desertmirage

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Inferior Mirage Grand Traverse Bay

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Mirages marins

Mirage is an optical phenomenon that creates the illusion of water, objects, or the sky appearing displaced from their original positions, typically viewed on the ground or sea level. Mirages occur when light rays bend or refract due to temperature gradients in the air, causing the light to travel in curved paths. This bending of light rays is most commonly due to a significant temperature difference between the ground (or water) and the air above it. Mirages can be categorized into two main types: inferior mirages and superior mirages, with a special case known as the Fata Morgana.

Types of Mirages

Inferior Mirage

An inferior mirage occurs when the ground is much hotter than the air above it. The most common example is the appearance of a water pool on the road on a hot day. In this case, the light rays from the sky bend upward upon hitting the hot surface, causing the sky or distant objects to appear reflected on the ground. Inferior mirages are most often observed in deserts or over hot roads.

Superior Mirage

A superior mirage happens under conditions where the air below the line of sight is colder than the air above it. This condition is known as a temperature inversion. Superior mirages can make objects like ships or islands appear elevated or "hovering" above their actual position. They are more common in polar regions but can also occur in any area where a temperature inversion is present.

Fata Morgana

The Fata Morgana is a complex form of superior mirage that is seen in a narrow band right above the horizon. It distorts the object or objects on which it is based, often making them unrecognizable. The mirage is named after the Arthurian sorceress Morgan le Fay, as it was believed to be an enchantment of ships to lure sailors to their doom. Fata Morgana mirages are most commonly observed in the Strait of Messina, between Sicily and Calabria, but can occur in several places worldwide under the right conditions.

Causes and Science Behind Mirages

Mirages are caused by the refraction, or bending, of light rays as they pass through air layers of different temperatures. The density of air decreases with temperature; thus, light travels faster through warmer air and slower through cooler air. This difference in speed causes the light rays to bend or refract. The specific type of mirage observed depends on the temperature gradient between the ground (or water) and the air.

Observation and Study

Mirages have been observed and recorded for centuries, with early explanations often rooted in mythology or supernatural beliefs. Today, the study of mirages falls within the field of meteorology and optical physics. Understanding mirages not only provides insights into atmospheric conditions but also has practical applications in navigation and safety in both maritime and desert environments.

Cultural Impact

Throughout history, mirages have inspired folklore, myths, and legends in various cultures. They have been interpreted as supernatural phenomena or omens. In literature and art, mirages are often used as metaphors for unattainable desires or unreachable goals.