Dust Storms of 2001

Late in June 2001, as southern winter transitioned to spring, the Mars Orbital Camera (MOC) system on Mars Global Surveyor (MGS) captured the moment that dust storms began to envelop parts of the southern hemisphere.
These storms began as cold air from the south polar cap moved northward toward the warmer air at the martian equator. By early July, dust storms had popped up all over the planet, particularly throughout the southern hemisphere. Soon, the entire planet--except the south polar cap--was enshrouded in dust.
There was never a time when the entire planet was in the midst of a single storm. Several large storms would occur at the same time, and dust was kicked high into the atmosphere to cause much of the rest of the planet to be obscured. The dust storms largely subsided by late September 2001, but the atmosphere remained hazy into November of that year.