NationMaster - Encyclopedia: Dust devil

A dust devil is a rotating updraft, ranging from small (half a meter wide and a few meters tall) to large (over 10 meters wide and over 1000 meters tall). Dust devils are usually harmless, but rare ones can grow large enough to threaten both people and property. They are comparable to tornadoes in that both are an unusual weather phenomenon of swirling air vortices. Tornadoes form as an updraft attached to a wall cloud at the back of a thunderstorm. Dust devils form as an updraft under sunny conditions during fair weather, rarely coming close to the intensity of a tornado. The phrase dust devil has several meanings. ... It has been suggested that Thermal be merged into this article or section. ... For other uses of Tornado, see Tornado (disambiguation). ...

Names

In the southwestern United States, a dust devil is sometimes called a "dancing devil". In Death Valley, California, it may be called a "sand auger" or "dust whirl".^[1]^{[dead link – history]}

The Australian "willy-willy" or "whirly-whirly" is thought to derive from Yindjibarndi or a neighbouring language.^[2]

The Navajo refer to them as chiindii, ghosts or spirits of dead Navajos. If a chindi spins clockwise it is said to be a good spirit; if it spins counterclockwise it is said to be a bad spirit. The Navajo people (or DinÃ©) of the Southwestern United States are currently the largest Native American tribe in North America, with an estimated tribal population of 300,000. ... A chindi is the ghost of the Navajo tribe believed to be released at dying breath. ...

Among the Kikuyu of Kenya, the dust devil is known as ngoma cia aka, meaning "women's devil/demon". This article or section does not cite any references or sources. ...

Formation

Dust devils form when hot air near the surface rises quickly through a small pocket of cooler low pressure air above it. If conditions are just right, the air may begin to rotate. As the air rises suddenly, the column of hot air is stretched vertically causing intensification of the spinning effect by the scientific principle conservation of angular momentum. The secondary flow in the dust devil causes other hot air to speed horizontally inward to the bottom of the newly-forming vortex. As more hot air rushes in toward the developing vortex to replace the air that is rising, the spinning effect becomes further intensified and self-sustaining. A dust devil, fully formed, is a funnel-like chimney through which hot air moves, both upwards and in a circle. As the hot air rises it cools, loses its buoyancy and eventually ceases to rise. As it rises it displaces air which descends outside the core of the vortex. This cool air returning acts as a balance against the spinning hot air outer wall and keeps the system stable.^[3] In physics, angular momentum intuitively measures how much the linear momentum is directed around a certain point called the origin; the moment of momentum. ...

The spinning effect, along with surface friction, usually will produce a forward momentum. The dust devil is able to sustain itself longer by moving over nearby sources of hot surface air. For other uses, see Friction (disambiguation). ...

As available extreme hot air near the surface is channeled up the dust devil, eventually surrounding cooler air will be sucked in. Once this occurs, the effect is dramatic and the dust devil dissipates in seconds. Usually this occurs when a dust devil isn't moving fast enough (depletion) or begins to enter a terrain where the surface temperatures are cooler, causing unbalance.^[1]

Solar power describes a number of methods of harnessing energy from the light of the sun. ...

Intensity and duration

On Earth, most dust devils are very small and weak, often less than 3 feet (0.9 meters) in diameter with maximum winds averaging about 45 miles per hour (70 km/h), and they often dissipate less than a minute after forming. On rare occasions, a dust devil can grow very large and intense, sometimes reaching a diameter of up to 300 feet (90 meters) with winds in excess of 60 mph (100 km/h), and can last for upwards of 20 minutes before dissipating.^[4] One such dust devil struck the Coconino County Fairgrounds in Flagstaff, Arizona on September 14, 2000. Extensive damage occurred to several temporary tents, stands and booths, as well as some permanent fairgrounds structures. In addition, several injuries were reported, but there were no fatalities. Based on the degree of damage left behind, it is estimated that the dust devil produced winds as high as 75 mph (120 km/h), which is equivalent to a moderate-strength EF0 tornado.^[5] In 2003, a dust devil lifted the roof off a two-story building in Lebanon, Maine, causing it to collapse and kill a man inside.^[6] Coconino County is located in the north central part of the U.S. state of Arizona. ... Nickname: Location in Coconino County the state of Arizona Coordinates: , Country State County Coconino County Government - Mayor Joseph C. Donaldson Area - City 98. ... is the 257th day of the year (258th in leap years) in the Gregorian calendar. ... Year 2000 (MM) was a leap year starting on Saturday. ... The Enhanced Fujita Scale, or EF Scale, is the scale for rating the strength of tornadoes in the United States estimated via the damage they cause. ... Lebanon is a town located in York County, Maine. ...

Electrical activities

Dust devils, even small ones (on Earth) can produce radio noise and electrical fields greater than 10,000 volts per meter.^[7] A dust devil picks up small dirt and dust particles. As the particles whirl around they bump and scrape into each other and become electrically charged. The whirling charged particles also create a magnetic field that fluctuates between 3 and 30 times each second.^[8]

These electrical fields assist the vortices in lifting materials off the ground and into the atmosphere. Field experiments indicate that a dust devil can lift 1 gram of dust per second from each square meter (10 lb/s from each acre) of ground it passes over. A large dust devil measuring about 100 meters (330 ft) across at its base can lift about 15 metric tons (17 short tons) of dust into the air in 30 minutes. Giant dust storms that sweep across the world's deserts contribute eight percent of the mineral dust in the atmosphere each year during the handful of storms that occur. In comparison, the significantly smaller dust devils that twist across the deserts during the summer lift about three times as much dust, thus having a greater combined impact on the dust content of the atmosphere. When this occurs, they are often called sand pillars.^[9]

Martian dust devils

Dust devils also occur on Mars, and were first photographed by the Viking orbiters in the 1970s. In 1997, the Mars Pathfinder lander detected a dust devil passing over it.^[10]^[11] Martian dust devils can be up to fifty times as wide and ten times as high as terrestrial dust devils, and large ones may pose a threat to terrestrial technology sent to Mars.^[12] A dust devil on Mars Credit: Malin Space Science Systems, MGS, JPL, NASA For more copyright info, see also: [1] [2] Source http://antwrp. ... A dust devil on Mars Credit: Malin Space Science Systems, MGS, JPL, NASA For more copyright info, see also: [1] [2] Source http://antwrp. ... Mars is the fourth planet from the Sun in the solar system, named after the Roman god of war (the counterpart of the Greek Ares), on account of its blood red color as viewed in the night sky. ... The Mars Global Surveyor (MGS) was a US spacecraft developed by NASA and the Jet Propulsion Laboratory and launched November 1996. ... Mars is the fourth planet from the Sun in the solar system, named after the Roman god of war (the counterpart of the Greek Ares), on account of its blood red color as viewed in the night sky. ... Viking mission profile. ... The 1970s decade refers to the years from 1970 to 1979, also called The Seventies. ... For the band, see 1997 (band). ... The Mars Pathfinder was launched on December 4, 1996 by NASA aboard a Delta II just a month after the Mars Global Surveyor was launched. ...

Mission members monitoring the Spirit rover on Mars reported March 12, 2005 that a lucky encounter with a dust devil has cleaned the solar panels of that robot. Power levels dramatically increased and daily science work was anticipated to be expanded.^[13] A similar phenomenon (solar panels mysteriously cleaned of accumulated dust) had previously been observed with the Opportunity rover, and dust devils had also been suspected as the cause.^[14]
The launch patch for Spirit, featuring Marvin the Martian. ... is the 71st day of the year (72nd in leap years) in the Gregorian calendar. ... Year 2005 (MMV) was a common year starting on Saturday (link displays full calendar) of the Gregorian calendar. ... The launch patch for Opportunity, featuring Duck Dodgers (Daffy Duck). ...

Download high resolution version (1024x256, 4307 KB) File links The following pages link to this file: Mars Categories: NASA images ... Download high resolution version (1024x256, 4307 KB) File links The following pages link to this file: Mars Categories: NASA images ...

Related phenomena

A Fire whirl or swirl, sometimes called fire devils or fire tornadoes, can be seen during intense fires in combustible building structures or more commonly in forest or bush fires. A fire whirl is a vortex-shaped formation of burning gases being released from the combustible material. The genesis of the vortex is probably similar to that of a dust devil. But, as distinct from the dust devil, it is improbable that the height reached by the fire gas vortex is greater than the visible height of the vortical flames because of turbulence in the surrounding gases which inhibit creation of a stable boundary layer between the rotating/rising gases relative to the surrounding gases.^[15] A fire whirl with flames in the vortex. ...

Hot cinders underneath freshly-deposited ash in recently burned areas may sometimes generate numerous dust devils. The lighter weight and the darker color of the ash may create dust devils that are visible hundreds of feet into the air.

Steam devils are phenomena often observed in the steam rising from power plants.^[16] A power station (also power plant) is a facility for the generation of electric power. ...

See also

A Gustnado is a type of short-lived cyclonic circulation that can form with severe thunderstorms. ... This article is about the weather phenomenon. ... A fire whirl with flames in the vortex. ... Waterspouts on the beach of Kijkduin near The Hague, the Netherlands on 2006 August 27. ... A landspout is a tornado not associated with the mesocyclone of a thunderstorm. ...

Notes

^ ^a ^b http://www.death-valley.us/article559.html
^ Dixon et al. (2006): p. 195.
^ Ludlum, David M. (1997). National Audubon Society Field Guide to North American Weather. Knopf. ISBN 0-679-40851-7.
^ Dust Devils: Ephemeral Whirlwinds Can Stir Up Trouble. Arizona Vacation Planner (unknown). Retrieved on 2007-10-05.
^ Damage From a Dust Devil at the Coconino County Fairgrounds - September 14, 2000. National Weather Service-Flagstaff, AZ (unknown). Retrieved on 2007-10-05.
^ NCDC: Event Details National Climatic Data Center Accessed 2008-06-05.
^ University of California, Berkeley (29 May 2002). "Stalking Arizona dust devils helps scientists understand electrical, atmospheric effects of dust storms on Mars". Press release. Retrieved on 2006-12-01.
^ Koch, J., and N.O. Renno (Dec. 5-9, 2005). "Convective-radiative feedback mechanisms by dusty convective plumes and vortices". Fall meeting of the American Geophysical Union.
^ Kok, J.F.; Renno, N.O. (2006). "Enhancement of the emission of mineral dust aerosols by electric forces". Geophysical Research Letters 33 (Aug. 28): L19S10. doi:10.1029/2006GL026284.
^ Metzger, S. M.. Dust Devil Vortices at the Ares Vallis MPF Landing Site (PDF). Mars Exploration Program. JPL. Retrieved on December 1, 2006.
^ Martian Dust Devils Caught. Climate Research USA. Ruhr-Universität Bochum (March 21, 2000). Retrieved on December 1, 2006.
^ Smith, Peter; Renno, Nilton (6 June 2001). Studying Earth Dust Devils For Possible Mars Mission. UniSci News. Retrieved on December 1, 2006.
^ David, Leonard (12 March 2005). Spirit Gets A Dust Devil Once-Over. Space.com. Retrieved on December 1, 2006.
^ Did You Know?. Mars Exploration Rovers. Cornell University. Retrieved on December 1, 2006.
^ WILDFIRE MODELING, IR OBSERVATIONS AND ANALYSIS
^ Lyons, Walter A. The Handy Weather Answer Book. Detroit, MI: Visible Ink Press, 1997.

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Contents

Names

Formation

Intensity and duration

Electrical activities

Martian dust devils

Related phenomena

See also

Notes

References

External links

Contents

Names GA_googleFillSlot("encyclopedia_square");

Formation

Intensity and duration

Electrical activities

Martian dust devils

Related phenomena

See also

Notes

References

External links

Names