Editing Dust storm (section)

== Causes ==
[[File:Global movement of dust from an Asian dust storm animation.gif|thumb|left|Animation showing the global movement of dust from an [[Asian dust]] storm.]]

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 called [[Saltation (geology)|saltation]]. 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 and [[Downhill creep|creep]].<ref name="vrs" />

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.<ref>{{cite web |url=http://www.eurekalert.org/pub_releases/2008-01/uom-esf010708.php |title=Electric Sand Findings, University of Michigan Jan. 6, 2008 |publisher=Eurekalert.org |date=2008-01-07 |access-date=2016-12-04 |url-status=live |archive-url=https://web.archive.org/web/20160520031124/http://www.eurekalert.org/pub_releases/2008-01/uom-esf010708.php |archive-date=2016-05-20}}</ref>

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 intense [[thunderstorm]]. 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 (meteorology)|precipitation]]—the type of dust storm which was common during the [[Dust Bowl]] years in the U.S. Following the passage of a dry cold front, [[convection|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 the [[particulates]]. In some cases, dust and sand may be confined to a relatively-shallow layer by a low-lying [[temperature inversion]]. In other instances, dust (but not sand) may be lifted as high as {{convert|6000|m|ft|sigfig=1|abbr=on}}. Dust storms are a major health hazard.

[[Drought]] and [[wind]] contribute to the emergence of dust storms, as do poor [[farming]] and grazing practices by exposing the dust and sand to the wind. [[Wildfires]] can lead to dust storms as well.<ref>{{cite web |url=https://theconversation.com/wildfires-often-lead-to-dust-storms-and-theyre-getting-bigger-194400 |title=Wildfires often lead to dust storms – and they're getting bigger |date=18 November 2022}}</ref>

One poor farming practice which contributes to dust storms is [[dryland farming]]. Particularly poor dryland farming techniques are [[Tillage#Intensive tillage|intensive tillage]] or not having established [[crop]]s or [[cover crop]]s when storms strike at particularly vulnerable times prior to [[revegetation]].<ref>{{cite web |title=Dust Storms Chapter |url=http://csc.uoregon.edu/opdr/sites/csc.uoregon.edu.opdr/files/docs/ORNHMP/OR-SNHMP_%2520dust-storms_chapter.pdf |work=Emergency Management Plan |publisher=State of Oregon |url-status=dead |archive-url=https://web.archive.org/web/20131021013222/http://csc.uoregon.edu/opdr/sites/csc.uoregon.edu.opdr/files/docs/ORNHMP/OR-SNHMP_%20dust-storms_chapter.pdf |archive-date=2013-10-21}}</ref> In a semi-arid climate, these practices increase susceptibility to dust storms. However, [[soil conservation]] practices may be implemented to control [[Erosion#Wind erosion|wind erosion]].