the cause of sand stroms？

As the force of wind passing over loosely held particles increases, the smallest particles first start to vibrate, then to saltate ("leap"), and to travel in suspension and to land again possibly bouncing or causing other particles to move. 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.[1]

Particles become loosely held mainly due to drought or arid conditions, and wind has varied causes. Gust fronts may be produced by the outflow of rain-cooled air from an intense thunderstorm, or they may represent a dry cold front, that is, a cold front that is moving into a dry air mass and is producing no precipitation. This is the type of dust storm which was common during the Dustbowl 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 init