Adust storm, also called asandstorm, is ameteorological phenomenon common inarid andsemi-arid regions.^[1] Dust storms arise when agust front or other strongwind blows loosesand anddirt from a dry surface. Fine particles are transported bysaltation and suspension, a process that moves soil from one place anddeposits it in another.

Dust storm
A sandstorm approachingAl Asad April 27, 2005.
Effect	May causecoughing and spreaddust.

The arid regions ofNorth Africa,the Middle East,Central Asia andChina are the main terrestrial sources of airborne dust. It has been argued that^{[2][unreliable source?]} poor management ofEarth'sdrylands, such as neglecting thefallow system, are increasing the size and frequency of dust storms from desert margins and changing both the local and global climate, as well as impacting local economies.^[3]

The termsandstorm is used most often in the context ofdesert dust storms, especially in theSahara Desert, or places where sand is a more prevalent soil type than dirt or rock, when, in addition to fine particles obscuring visibility, a considerable amount of larger sand particles are blown closer to the surface. The termdust storm is more likely to be used when finer particles are blown long distances, especially when the dust storm affectsurban areas.

As the force of dust passing over loosely held particles increases, particles of sand first start to vibrate, then to move across the surface in a process calledsaltation. As they repeatedly strike the ground, they loosen and break off smaller particles of dust which then begin to travel in suspension. At wind speeds above that which causes the smallest to suspend, there will be a population of dust grains moving by a range of mechanisms: suspension, saltation andcreep.^[3]

A study from 2008 finds that the initial saltation of sand particles induces a static electric field by friction. Saltating sand acquires a negative charge relative to the ground which in turn loosens more sand particles which then begin saltating. This process has been found to double the number of particles predicted by previous theories.^[4]

Particles become loosely held mainly due to a prolonged drought or arid conditions, and high wind speeds. Gust fronts may be produced by the outflow of rain-cooled air from an intensethunderstorm. Or, the wind gusts may be produced by a drycold front: that is, a cold front that is moving into a dry air mass and is producing noprecipitation—the type of dust storm which was common during theDust Bowl years in the U.S. Following the passage of a dry cold front,convective instability resulting from cooler air riding over heated ground can maintain the dust storm initiated at the front.

In desert areas, dust and sand storms are most commonly caused by either thunderstorm outflows, or by strong pressure gradients which cause an increase in wind velocity over a wide area. The vertical extent of the dust or sand that is raised is largely determined by the stability of the atmosphere above the ground as well as by the weight of theparticulates. In some cases, dust and sand may be confined to a relatively-shallow layer by a low-lyingtemperature inversion. In other instances, dust (but not sand) may be lifted as high as 6,000 m (20,000 ft). Dust storms are a major health hazard.

Drought andwind contribute to the emergence of dust storms, as do poorfarming and grazing practices by exposing the dust and sand to the wind.Wildfires can lead to dust storms as well.^[5]

One poor farming practice which contributes to dust storms isdryland farming. Particularly poor dryland farming techniques areintensive tillage or not having establishedcrops orcover crops when storms strike at particularly vulnerable times prior torevegetation.^[6] In a semi-arid climate, these practices increase susceptibility to dust storms. However,soil conservation practices may be implemented to controlwind erosion.

A sandstorm can transport and carry large volumes of sand unexpectedly. Dust storms can carry large amounts of dust, with the leading edge being composed of a wall of thick dust as much as 1.6 km (5,200 ft) high. Dust and sand storms which come off theSahara Desert are locally known as asimoom or simoon (sîmūm, sîmūn). Thehaboob (həbūb) is a sandstorm prevalent in the region ofSudan aroundKhartoum, with occurrences being most common in the summer.

TheSahara desert is a key source of dust storms, particularly theBodélé Depression^[7] and an area covering the confluence ofMauritania,Mali, andAlgeria.^[8] Sahara dust is frequently emitted into the Mediterranean atmosphere and transported by the winds sometimes as far north as central Europe and Great Britain.^[9]

Saharan dust storms have increased approximately 10-fold during the half-century since the 1950s, causingtopsoil loss inNiger,Chad, northernNigeria, andBurkina Faso.^[10] In Mauritania there were just two dust storms a year in the early 1960s; there are about 80 a year since 2007, according to EnglishgeographerAndrew Goudie, professor at theUniversity of Oxford.^[11][12] Levels of Saharan dust coming off the east coast of Africa in June 2007 were five times those observed in June 2006, and were the highest observed since at least 1999, which may have cooled Atlantic waters enough to slightly reduce hurricane activity in late 2007.^[13][14]

Dust storms have also been shown to increase the spread of disease across the globe.^[15]Bacteria andfungus spores in the ground are blown into the atmosphere by the storms with the minute particles and interact with urban air pollution.^[16]

Short-term effects of exposure to desert dust include immediate increasedsymptoms and worsening of thelung function in individuals withasthma,^[17][18] increasedmortality andmorbidity from long-transported dust from both Saharan^[19] andAsian dust storms^[20] suggesting that long-transported dust storm particles adversely affects the circulatory system.Dust pneumonia is the result of large amounts of dust being inhaled.

Prolonged and unprotected exposure of therespiratory system in a dust storm can also causesilicosis,^[21] which, if left untreated, will lead toasphyxiation; silicosis is an incurable condition that may also lead tolung cancer. There is also the danger ofkeratoconjunctivitis sicca ("dry eyes") which, in severe cases without immediate and proper treatment, can lead toblindness.^[22]

Dust storms cause soil loss from the drylands, and worse, they preferentially remove organic matter and the nutrient-rich lightest particles, thereby reducing agricultural productivity. Also, the abrasive effect of the storm damages young crop plants. Dust storms also reduce visibility, affecting aircraft and road transportation.^{[This paragraph needs citation(s)]}

Dust can also have beneficial effects where it deposits: Central and South American rainforests get significant quantities of mineral nutrients from the Sahara;^[23][24] iron-poor ocean regions get iron; and dust in Hawaii increasesplantain growth. In northern China as well as the mid-western U.S., ancient dust storm deposits known asloess are highly fertile soils, but they are also a significant source of contemporary dust storms when soil-securing vegetation is disturbed.^{[This paragraph needs citation(s)]}

Iranian cities existence are challenged by dust storms.^[25]

Dust storms are not limited to Earth and have also been known to form onMars.^[26] These dust storms can extend over larger areas than those on Earth, sometimes encircling the planet, with wind speeds as high as 25 m/s (60 mph). However, given Mars' much lower atmospheric pressure (roughly 1% that of Earth's), the intensity of Mars storms could never reach the hurricane-force winds experienced on Earth.^[27] Martian dust storms are formed when solar heating warms the Martian atmosphere and causes the air to move, lifting dust off the ground. The chance for storms is increased when there are great temperature variations like those seen at the equator during the Martian summer.^[28]

• Coccidioidomycosis – Fungal infection
• Dry line – Boundary between moist and dry air
• Dust storm warning – Weather warning in the United States
• Haboob – Type of intense dust storm
• Iberulite
• List of dust storms
• Mineral dust – Dust made from soil minerals
• Saharan Air Layer – Hot, dry and sometimes dust-laden atmospheric layerPages displaying short descriptions of redirect targets
• Shamal (wind) – Northwesterly wind blowing over Iraq and the Persian Gulf state
• Sirocco – Mediterranean wind

• 12-hour U.S. map of surface dust concentrations Mouse-over an hour block on the row for 'Surface Dust Concentrations'
• Dust in the WindArchived 2020-04-16 at theWayback Machine
• Photos of the April 14 1935 and September 2 1934 dust storms in theTexas Panhandle hosted by thePortal to Texas History.
• University of Arizona Dust Model Page
• Photos of a sandstorm in Riyadh in 2009 from the BBC Newsbeat website
• Dust storm in Phoenix Arizona via YouTube