Dust Storms

Common in arid and semi- arid areas as they are drier - increased availability of dust/ sand:

• Arise when loose sand and dust blow from a dry surface
• Particles are transported by saltation and suspension - causes soils to erode
• The ability of wind to carry particles is less than water or ice because air is less dense but it can spread over a larger area

Causes are often wind, source materials and human activities

Pratt (2004) - Dust and sand storms in Asia are becoming more frequent and intense, with some areas experiencing a fivefold increase in the last 50 years

• Due to increased pollution and desertification
• Global warming - drier winters are seeing more dust storms in spring months

Sandstorms - usually used when referring to desert blown sediments - when, in addition to fine particles obscuring visibility, a considerable amount of larger sand particles are blown closer to the surface.

Dust storms - more likely to be used for the blowing of finer particles that occurs over long distances and through urban areas - e.g. seds that are less than 63 microns (silts and clays)

Only fine grained material is able to be transported long distances and high into the air in a dust storm; as opposed to seds in a sand storm which generally travel only 2m above ground surface levels (Pye, 2005)

Two principal wind-erosion processes are deflation, the removal and lifting of individual loose particles, and abrasion, the grinding of rock surfaces with a “sandblasting” action by particles captured in the air

Remote sensing can be used to capture satellite images of dust storms and predict where they are likely to flow to - can be useful in implementing mitigation strategies:

• Pratt (2004) - 
  • Predictive models are currently in routine use in China and in experimental use in several other countries
  •  It is used for multi-week predictions and even seasonal predictions of conditions conducive to dust-storm development  
  •  The models take into account several complex factors, including surface-vegetation cover and land-surface types, as well as soil type, texture and moisture
• Governments are also working together in N China to reduce human impacts which lead to dust stroms - e.g. land clearance, mining, reducing pollution and over abstraction of water etc

Source materials from sand dunes - fine materials transported long distances and deposited…