Dust storms begin as winds lift small particles of dry, loose soil into the air. While larger particles often fall back to the ground quickly, smaller ones can stay aloft for days. These small particles often travel thousands of miles, including across continents and oceans.
Large-scale synoptic dust storms can be up to 1500 miles wide. They begin when cold fronts cut under warm air masses, bringing strong winds across hot, dry surfaces. The increase in the pressure gradient leads to high winds with gusts up to 100 miles per hour. The higher the winds lift the dust particles, the longer they remain suspended in the air. The storm sometimes deposits dust from the North African desert in the Caribbean. In the Persian Gulf, dust storms often block the sun for up to five days.
Mesoscale dust storms range from 50 to 100 feet across. Some form as winds rush down the mountains or through gaps in mountain ranges. Others, called haboobs, occur due to the convection currents from thunderstorms. Haboobs are what most people think of as dust storms. They are violent storms that often down power lines. These thick dust storms limit visibility, causing problems for airplanes and automobiles. The fine particles of dust also cause health issues for humans, especially those with asthma.