NASA recently published an intriguing close-up image (Fig. 1) of the surface of Mars, the Red Planet. The image, acquired by a sophisticated camera aboard the Mars Reconnaissance Orbiter (MRO) spacecraft, shows a strong whirlwind, swirling in a plain in the Martian northern hemisphere.
The afternoon whirlwind on Mars lofted a twisting column of dust over 800 meters high, on 16 February 2012, and displays a thin arc produced by a westerly breeze partway up its height. The dust plume is about 30 meters wide. Traces of many previous whirlwinds, visible as streaks on the Martian soil, are also recorded in Fig. 1.
During this time of Martian year the planet is farthest from the Sun. Quite like Earth, winds on Mars are powered by Sun’s heat. Exposure to the Sun's rays decreases during this season, however, the Martian whirlwinds do occur.
Whirlwinds, also known as dust devils, occur on Earth as well as on Mars. They are spinning columns of air, made visible by the dust they carry. Unlike a tornado, a dust devil usually forms on a clear day when the ground is heated by the Sun, warming the air immediately above the ground. As warm air near the surface rises quickly through a small pocket of cooler air above it, the air may begin to rotate, if conditions are just right.
MRO has been studying Mars with six devices since 2006. The Mars-orbiting probe continues to yield insights into the planet's ancient environments and how processes such as wind, meteorite impacts and seasonal frosts continue to affect the Martian surface today. This mission has obtained more data about Mars than all other orbital and surface missions combined.
References
NASA
www.nasa.gov/