Sandstorms are not just the stuff of legend; rather, they're a real phenomenon in which strong, dry gusts of wind sweep over a desert area and create massive "clouds" of sand and dust. Sandstorms reduce visibility and can grind the daily life of a city to a halt if they are severe enough. They are rare in the United States but typically occur in the Middle East and China.
Forceful desert winds are responsible for sandstorms. The wind originates as a result of convection currents created by intense heating of the ground. The storm-causing winds that blow in North Africa and Arabia carries sand all the way to Europe and to significant distances out to sea. Typical sandstorms only reach heights of 49 feet. In high-velocity winds, a phenomenon known as saltation explains the projection of sand particles and occurs when grains of sand are momentarily lifted and then bounced along the surface in a hopping motion. As different sand particles collide, the impact may lift them into the air, at which point the force of gravity pushes them down again. The process then repeats, getting stronger and stronger as the storm blows across the desert.
Sandstorms are relatively rare in the United States, although they sometimes occur in the desert areas of the southwest. Most sandstorms occur in the springtime in the dry countries of the Middle East and North Africa. Afghanistan, Algeria, Bahrain, China, Egypt, Iran, Iraq, Israel, Kuwait, Lebanon, Libya, Mongolia, Oman, Qatar, Saudi Arabia, Sudan, Syria, United Arab Emirates, Uzbekistan are the countries with the highest incidence of sandstorms. Sandstorms may even take place on Mars.
Prediction and Control
Sandstorms can be scientifically predicted, but the limited resources of the countries where they occur most frequently limit predictive capabilities. For example, China endured a very serious sandstorm in March 2002, but the negative impact was limited because the event was forecast. Meteorological satellites help scientists predict the occurrence of storms. Minimising deforestation and drought-prone farming techniques can reduce the occurrence of sandstorms.
Because the wind can displace so much sand, it can cover an entire road and interfere with travel. The thick dust clouds reduce visibility, build up on skin and clothes, penetrate the interior of buildings and contaminate food and drinking water. The force of sandstorms erodes textile materials, such as protective outerwear and shoes. Additionally, high sand concentrations can induce or aggravate respiratory problems in humans.
These storms also wreak havoc on machinery, electronics and buildings. Blowing sand and dust scour surfaces and wear away protective coverings (i.e., glass becomes frosted, wire wrap wears away and electric circuits ground out). Unfortunately, the more sophisticated an electrical system is, the more dust affects it. Dust compacts easily, solidifies with little added moisture and combines with lubricants --- often resulting in clogged and/or jammed equipment and machinery. Dust and sand storms also set up electrostatic discharges that, while not typically fatal, can have negative consequences in fuelling operations, computer or electrical systems.