Martian dust devils may get a boost from their own shadows

New Scientist : Due to Mars’s thin atmosphere, dust devils require strong winds to keep the sand grains swirling off the ground. Gerhard Wurm of the University of Duisburg-Essen in Germany suggests that the temperature difference between shadowed and sunlit ground may be enough to kick extra dust into the air. To test his theory, he dropped a capsule full of Mars-like sand down a 110 m drop tower, shined a laser light on the dust as it fell, and measured the dust grains as they bounced around inside. When Wurm switched off the laser, he noted that the grains’ movement increased by a factor of 10, which he attributed to the cooling of the dust. He says that on Mars the dust devil’s shadow could have a similar cooling effect. The resulting temperature changes could cause gases in the Martian soil to move around and, after a buildup of pressure, explode and lift sand into the air. That feedback effect could fuel the large dust storms occasionally seen on Mars.