Sandstorm is a wind storm that carries sand through the air. The wind-driven sand forms a low cloud near the ground. Most of the sand particles do not rise higher than 10 feet (3 meters), but some grains rise up to 50 feet (15 meters). The grains average from 1/170 to 1/85 inch (0.15 to 0.30 millimeter) in diameter. During sandstorms, wind speeds exceed 10 miles (16 kilometers) per hour. The storms may last three to five hours. They tend to form during the day and die out at night.