Where does all this dust come from? It is believed to be the result of erosion caused by winds. Because the Martian atmosphere is so thin, it may be difficult for dust particles to move, but if the winds are turbulent enough larger particles can become airborne more easily, carrying smaller dust particles with them. Perseverance and previous Mars rovers have mostly observed vortices of air that were associated with either dust devils or convection, during which hot air rises.
CaSSIS and HRSC data showed that most dust devils are found in the northern hemisphere of Mars, primarily in Amazonis and Elysium Planitia, with Amazonis Planitia being a hotspot. They can be tossed by winds over both rough and smooth terrain, but they spread far across the Southern Hemisphere, with some traveling across almost half of the planet. Seasonal occurrence of dust devils is highest during the southern summer, while they are almost non-existent in the late northern autumn.
Martian dust intensity peaks between mid-morning and mid-afternoon, although they can also occur from early morning to late afternoon. They also migrate to the Martian north pole during the northern summer and to the south pole during the southern summer. Southern dust devils move faster than those in the Northern Hemisphere. The speed set by the winds can be as fast as 44 meters per second (about 98 miles per hour), far faster than the speed of dust devils on Earth.
weather the storm
The speed of dust devils on the Red Planet has also been found to be increasing very rapidly. These severe storms are associated with winds that move with themselves but do not form a vortex, called non-vortex winds. It takes only a few seconds for these winds to reach such high velocity that they are able to pick up dust particles from the ground and move them into the atmosphere. It’s not just dust devils that do this – the team found that non-vortex winds also pick up large amounts of dust particles on their own, much more than previously thought, and create dusty haze in the atmosphere.