Dust storms form when wind and other factors cause dust to rise high in the air, where the wind whips it around, causing destruction and damage. Dust storms are also called sand storms, though both require the same kind of light, dry dust in order to form. Sometimes, dust storms are so large that they affect local weather or create unusual sunrises or sunsets.
Dust storms require wind speed of only about 9 miles per hour to lift the dust off the ground; however, most substantial dust storms have much faster wind speeds than this. When larger winds are at play, the sand is stratified into three different levels. The lightest dust moves high into the air, sometimes exceeding 2,000 feet in altitude. At the same time, the heaviest particles stay near the ground, moving in a form known as “creeping.” However, it is the particles in the middle of the size range that cause the most damage. These medium-sized particles alternately rise into the air and fall back to the ground, crashing into other particles of dust as they do. This causes additional particles of dust and sand to fly up into the air, where they can become part of the storm as well.
Some sand storms, such as those in the Sahara Desert, are so consistent and so large that they are part of the reason that Miami has such bright red sunrises.