Online Astronomy eText: The Planets
Wind Effects on Mars Link for sharing this page on Facebook
     Although the Martian atmosphere is very thin, it can have high velocities driven by temperature differences between sunny and dark areas, and winter and summer hemispheres. Those winds produce many effects. Aside from the extensive erosional features shown just below and at Erosional Features on Mars, winds raise dust devils, dust storms which on rare occasions can cover the entire planet with an impenetrable veil, and create sand dunes and ripples, wind shadows and other features. Pictures of such features are shown below.

Candor and Ophir Chasmata
A 500 mile wide section of Valles Marineris, an immense depression created by wind erosion of stress fractures in the Martian surface, and subsequent wall collapse (landslides). (Viking Project, NASA, apod030218)

Wind shadows caused by small craters

A more detailed image of crater wind shadows.
The region shown here is at 13.7 degrees South latitude and 131.7 degrees West longitude.

Old, partially buried crater in Arabia Terra, with sand dunes in and around it (near 20.9N, 320.8W)

Below: Near the end of the Martian winter, clouds of fog and dust cover parts of southern Mars in this image taken May 20, 2003 by the Mars Global Surveyor. Water vapor fog clouds cover the summits of the volcanoes on the Tharsis ridge, below and to the left of center, and Olympus Mons, at the far left. Fog and dust also shrouds the region south of Labyrinthus Noctis, the fractured terrain below and to the right of the Tharsis ridge (a closeup of that region is shown below this image). Meanwhile, the remnants of the north polar cap are visible at the top of the image. (MSSS, JPL, NASA, apod030602)

Below: A closeup of clouds of fog and dust in Syria Planum, a raised area to the south of Labryinthus Noctis, the heavily fractured zone at the top of the image. This picture was taken on May 21, 2003, a day after the one shown above (this image would have to be rotated about 45 degrees clockwise to correspond to the orientation of the previous image). (NASA/JPL/Malin Space Science Systems, Planetary Photojournal)

Below: Morning mist and clouds in canyons near Labyrinthus Noctis, as photographed by the Viking orbiter in the mid 1970's. It is thought that water vapor condenses in the canyons during the night, then evaporates into misty clouds in the morning. (Viking Project, USGS, JPL, NASA, apod010417)

View of dust storms at perihelion summer of 2001, centered on the Tharsis Ridge area. On the left, the appearance of Mars on June 10, about the time the dust storms started. On the right, the region's appearance on July 31, when the dust storms were near their peak. (NASA, JPL, Malin Space Science Systems)

Below: Another view of the 2001 Martian dust storms, centered on Shiaparelli crater. In the left image dust storms are brewing around the Hellas basin (at the right lower limb of the planet), while fog and dust shrouds the north polar region. In the right image virtually the entire planet is engulfed in dust. This sort of planet-wide dust storm occurs at about one perihelion summer in ten, as a result of a relative excess of heat in the regions heated both by the relatively close approach to the Sun, and otherwise normal seasonal changes in weather. Such storms never occur at aphelion summer, and even at perihelion summer dust storms rarely cover even half the planet. (MSSS, JPL, NASA, apod021224)

Below: The growth of a major perihelion summer dust storm on Mars, as observed by the Thermal Emission Spectrometer on the Mars Global Surveyor during its close approach to the Sun in 2001. Blue represents clear skies, and red extremely dusty and essentially opaque regions. The gray areas near the poles are regions that were not observed because of the inclination of the spacecraft's orbit. (TES Team, MGS, JPL, NASA, apod010727)

Below: Dust storms near the North Pole of Mars during the Northern hemisphere's spring of late 2002. As the north polar cap thaws temperature differences between the whiter dry ice snow in the polar cap and the darker, recently thawed regions to the south cause swirling winds which stir up dust storms (the dark choppy and wavy regions extending away from the polar cap). (MSSS, JPL, NASA, apod021224)

Below: A dust devil caught in the act of scouring a dark trail on the surface of sand dunes. Such minor tornadoes can be up to five miles high, but last as little as a few minutes. (Malin Space Science Systems, MGS, JPL, NASA, apod020903)

Many dust devils have passed by rovers and landers on the surface of Mars. In fact some of them have helped their missions, as they removed dust deposited on solar panels during planet-wide dust storms. A few of them have even been photographed as they passed by, as in the animation below, imaged by the Spirit rover. (Mars Exploration Rover Mission, JPL, NASA , apod050426)

Below: Sand dunes in Proctor crater. (Malin Space Science Systems, MGS, JPL, NASA, apod010226)

Below: Another view of sand dunes, in Rabe crater, including signs of dust devil trails, and sand slippage (indicated by arrows). (Malin Space Science Systems, MGS, JPL, NASA, apod000202)

Below: Dust devil trails blanketing the region around and within a Martian crater. Such trails are not permanent, as dust storms and changes in seasonal winds will eventually remove all trace of them; so to see so many in such a small region the number of dust devils passing through the area in a given period of time must be very large. (Malin Space Science Systems, MGS, JPL, NASA, apod031230)

Below: In most regions of Mars dust devils remove light-colored dust from the surface, exposing darker material lying below and leaving dark trails. But in this image taken near Schiaparelli crater, the overlying material that was scoured away is darker than the underlying material, so the tracks are lighter than their surroundings. (NASA, JPL, Malin Space Science Systems)

Below: Dust devils up to five miles high scour light-colored dust from the surface of Mars, exposing the material below. Usually the dark trails left by such winds are noticeable but not particularly dramatic; but in the case of the dunes shown here the underlying material was much darker than the dust on the surface, creating an almost calligraphic image. Close inspection of the image reveals that there is no alteration of the waves on the surface of the dunes, indicating that only the lightest, smallest particles were removed by the dust devils. In the dense atmosphere of the Earth, high-velocity winds have considerable force, and dust devils would probably physically alter the surface; but on Mars the extremely thin atmosphere has far less scouring power. (HiRISE, MRO, LPL (U. Arizona), NASA, apod091021)