© Steve Jurvetson
Gerlach, Nevada, United States of America
Latitude: 40° 39' 20'' N
Longitude: 119° 37' 24'' W
21 July 2007 1415 (Local Time)
Image P/S code: S.12.2.3
Image I.D.: 5433
-
Dust whirls (dust devils) and mirage
Dust whirls (dust devils) occur when the air near the ground is very unstable, such as when the soil is strongly heated by the Sun. The same conditions are also conducive to the appearance of an inferior mirage, as seen in this photograph taken over the Black Rock Desert in Nevada, USA.
A dust whirl or sand whirl (dust devil)is an ensemble of particles of dust or sand, sometimes accompanied by small litter, raised from the ground in the form of a whirling column of varying height with a small diameter and an approximately vertical axis.
Mirages are an optical phenomenon caused by the curving of light rays passing through layers of air with changing refractive index due to differences in temperature and density. In an inferior mirage, the image of a distant object is displaced downwards. Note the inverted image of part of the hillside here.
Links in the image description will highlight features on the image. Mouse over the features for more detail.
© Steve JurvetsonGerlach, Nevada, United States of AmericaLatitude: 40° 39' 20'' NLongitude: 119° 37' 24'' W21 July 2007 1415 (Local Time)Image P/S code: S.12.2.3Image I.D.: 5433
Dust whirl (dust devil)
A dust devil (dust whirl or sand whirl) is an ensemble of particles of dust or sand, sometimes accompanied by small litter, raised from the ground in the form of a whirling column about an approximately vertical axis. Dust devils occur when the air near the ground is very unstable, such as when the soil is strongly heated by the Sun.
Links in the image description will highlight features on the image. Mouse over the features for more detail.
© Stan Celestiannear Glendale, Arizona, United States of AmericaLatitude: 33° 33' 34'' NLongitude: 112° 22' 44'' W04 July 2004 1550 (Local Time)Image P/S code: P.12.2.3Image I.D.: 5434
Inferior (hot-road) mirage
A mirage is an optical phenomenon produced when light is refracted, or bent, by passing through layers of air of different temperature and density.
The "hot-road" mirage is one of the most commonly seen mirages, giving the illusion of an area of water on a road surface. Similar mirages occur over deserts. The mirage occurs when there is a strong vertical temperature gradient in the air near the ground surface, typically due to strong heating of the road or desert surface by the Sun. Cooler air lies above the significantly warmed air near the ground surface.
This type of mirage is known as an inferior mirage because the image of distant objects is displaced downwards. Rays of light from the sky and other objects are refracted as they pass through the air of changing temperature and density and are bent upwards towards the observer; thus, light from the sky appears as though it is water on the ground.
The inferior mirage shown in this photograph, taken in summertime on the island of Cyprus in the Mediterranean, shows multiple mirage images of the car and sky due to the effects of a slightly undulating road surface.
A slight distortion in the shape of distant objects can also be seen due to shimmer. Shimmer typically occurs over land when the surface is hot and the Sun is shining brightly, and is caused by short period fluctuations of the refractive index of air as a result of the motion of small parcels of air.
Links in the image description will highlight features on the image. Mouse over the features for more detail.
© George AndersonBetween Polis and Pomos, CyprusLatitude: 35° 5' 57'' NLongitude: 32° 30' 1'' E01 August 2011 1256 (Local Time)Camera direction: towards SWImage P/S code: P.13.7.1Image I.D.: 4133