A strong, turbulent wind bearing large clouds of dust. The suspended dust consists predominantly of mineral particles with diameters less than 100 micrometers. Sand storms differ from dust storms in that the particles are much larger and have high settling speeds. When the wind and turbulence weaken, the larger particles settle out rapidly, leaving behind a cloud of dust with diameters mainly under 20 μm. Wind systems can carry these clouds many thousands of miles, in some cases across oceans.