A dust devil moves across Gusev Crater on the Red Planet. Faster wind speeds on Mars help keep the dust suspended in the thin martian atmosphere. NASA/JPL/Texas A&M
Mars requires a wind speed about 10 times faster than on Earth to lift dust. Once the dust is off the surface, it needs to remain suspended in the air to form a cloud. Because Mars is less massive and thus has a lower surface gravity than Earth, dust falls to the surface more slowly.
