Dust Storms

Dust storms are windstorms that severely blow dust clouds across a large area in arid or semi-arid regions. Dust storms are different from dust devils, which are small atmospheric dust-filled vortices created by differences in surface heating during fair, hot weather. Dust storms can cause poor air quality, decrease visibility, can be hazardous to human and animal health, can interfere with telecommunications, erode away the topsoil, block sunlight, and even can greatly influence not only local, but regional and global weather patterns by accumulating and transporting dust in the atmosphere. For example, after a dust storm in the Sahara, dust can move up to high altitudes, and can be carried hundreds or even thousands of miles away by air streams, causing an illness destroying Caribbean coral reefs, resulting in asthma outbreaks in the

United States, or providing good nutrients to the Amazonian rain forests. Another example is the dust storm in 2001 that began in Mongolia and gathered industrial pollution from China, then caused a haze in a quarter of the United States mainland.

Although dust storms occur naturally, some anthropogenic activity such as removal of vegetation or overgrazing can increase the amount of sediment available for dust storm events. An example of a prolonged impact of dust storms is the historical event called Dust Bowl in the 1930s, which was a disaster both with ecological and societal consequences. The Dust Bowl took place in the southern Great Plains of the United States, including parts of Kansas, Oklahoma, Texas, New Mexico, and Colorado, and was caused by the combination of poor agricultural practices and years of sustained drought. Extreme weather and artificially eroded soils resulted in terrible dust storms alternating with drought, heat, blizzards and floods. The land dried up because the original grasslands holding the soil in place were either plowed, then planted with wheat for many years, or because of overgrazing. Consequently, great clouds of dust and sand carried by the wind covered the area, sometimes even reaching as far as the Atlantic coast. In many places 8–10 cm (3–4 in) of topsoil was blown away. In 1935, programs for soil conservation and for rehabilitation of the Dust Bowl started, including seeding large areas in grass, crop rotation, contour plowing, terracing, and strip planting. Accordingly, subsequent droughts in the region had a much less impact, because the available dust for dust storms was greatly reduced by improved agricultural practices.

See also Desert and desertification; Erosion