Editing Mirage (section)

==Inferior mirage==
[[File:Mirage-diagram.svg|thumb|350px|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.]]
In an inferior mirage, the mirage image appears below the real object. The real object in an inferior mirage is the (blue) [[sky]] or any distant (therefore bluish) object in that same direction. The mirage causes the observer to see a bright and bluish patch on the ground.

[[ray (optics)|Light rays]] coming from a particular distant object all travel through nearly the same layers of air, and all are [[refraction|refracted]] at about the same [[Snell's law|angle]]. Therefore, rays coming from the top of the object will arrive lower than those from the bottom. The image is usually upside-down, enhancing the [[illusion]] that the sky image seen in the distance is a [[specular reflection]] on a puddle of water or oil acting as a [[mirror]].

While the aero-dynamics are highly active, the image of the inferior mirage is stable unlike the fata morgana which can change within seconds. Since warmer air rises while cooler air (being [[density|denser]]) sinks, the layers will mix, causing [[turbulence]]. The image will be [[distortion|distorted]] accordingly; it may vibrate or be stretched vertically ([[Looming and similar refraction phenomena#Towering and stooping|towering]]) or compressed vertically ([[Looming and similar refraction phenomena#Stooping|stooping]]). A combination of vibration and extension are also possible. If several [[planetary boundary layer|temperature layers]] are present, several mirages may mix, perhaps causing double images. In any case, mirages are usually not larger than about half a degree high (roughly the [[angular diameter]] of the Sun and Moon) and are from objects between dozens of meters and a few kilometers away.

<gallery widths="200px" heights="140px">
File:Desertmirage.jpg|An inferior mirage seen in the [[Mojave Desert]] in a Nevada [[spring (season)|spring]]
File:Inferior Mirage Grand Traverse Bay.jpg|An inferior mirage over [[Grand Traverse Bay]] in [[Michigan]]
</gallery>
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===Heat haze===
{{see also|Schlieren|Twinkling|Astronomical seeing}}
{{Multiple image
 | direction   = horizontal
 | total_width = 500
 | image1      = Hot road mirage.jpg
 | caption1    = A hot-road mirage, in which "fake water" appears on the road, is the most commonly observed instance of an inferior mirage.
 | image2      = Swiss F-5E at Fairford.JPG
 | caption2    = Heat haze seen through [[exhaust gas]] from a jet engine
}} 

''Heat haze'', also called ''heat shimmer'', refers to the inferior mirage observed when viewing objects through a [[air mass (astronomy)|mass]] of heated air. Common instances when heat haze occurs include images of objects viewed across [[asphalt concrete]] (also known as [[Tarmacadam|tarmac]]), roads and over masonry rooftops on hot days, above and behind fire (as in burning [[candle]]s, [[patio heater]]s, and [[campfire]]s), and through [[exhaust gas]]es from [[jet engine]]s. When appearing on roads due to the hot asphalt, it is often referred to as a "highway mirage". It also occurs in deserts; in that case, it is referred to as a "desert mirage". Both tarmac and sand can become very hot when exposed to the sun, easily being more than {{convert|10|C-change}} higher than the air {{one2a|{{convert|1|m|ft|abbr=off|spell=in|sp=us}}}} above, enough to make conditions suitable to cause the mirage.

[[Convection]] causes the temperature of the air to vary, and the variation between the hot air at the surface of the road and the denser cool air above it causes a [[gradient index optics|gradient]] in the [[refractive index]] of the air. This produces a blurred [[schlieren|shimmering effect]], which hinders the ability to [[optical resolution|resolve]] the image and increases when the image is [[magnification|magnified]] through a [[telescope]] or [[telephoto lens]].

Light from the sky at a shallow angle to the road is [[refraction|refracted]] by the index gradient, making it appear as if the sky is reflected by the road's surface. This might appear as a pool of liquid (usually water, but possibly others, such as oil) on the road, as some types of liquid also reflect the sky. The illusion moves into the distance as the observer approaches the miraged object giving one the same effect as approaching a rainbow.

Heat haze is not related to the atmospheric phenomenon of [[haze]].
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