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. Or, the wind gusts may be produced by a dry cold front: that is, a cold front that is moving into a dry air mass and is producing no precipitation-the type of dust storm which was common during the Dust Bowl years in the U.S. Gust fronts may be produced by the outflow of rain-cooled air from an intense thunderstorm. Particles become loosely held mainly due to a prolonged drought or arid conditions, and high wind speeds. This process has been found to double the number of particles predicted by previous theories. Saltating sand acquires a negative charge relative to the ground which in turn loosens more sand particles which then begin saltating. Ī study from 2008 finds that the initial saltation of sand particles induces a static electric field by friction. 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 and creep. As they repeatedly strike the ground, they loosen and break off smaller particles of dust which then begin to travel in suspension. The term dust storm is more likely to be used when finer particles are blown long distances, especially when the dust storm affects urban areas.Īnimation showing the global movement of dust from an Asian dust storm.Īs 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 called saltation.
The term sandstorm is used most often in the context of desert dust storms, especially in the Sahara 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. It has been argued that poor management of Earth's drylands, such as neglecting the fallow 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. The arid regions of North Africa, the Arabian peninsula, Central Asia and China are the main terrestrial sources of airborne dust. Fine particles are transported by saltation and suspension, a process that moves soil from one place and deposits it in another. Dust storms arise when a gust front or other strong wind blows loose sand and dirt from a dry surface. A dust storm, also called a sandstorm, is a meteorological phenomenon common in arid and semi-arid regions.
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