http://www.universetoday.com/94437/new-gigantic-tornado-spotted-on-mars/

A Martian dust devil roughly 12 miles (20 kilometers) high was
captured winding its way along the Amazonis Planitia region of Northern Mars on
March 14, 2012 by the High Resolution Imaging Science Experiment (HiRISE) camera
on NASA's Mars Reconnaissance Orbiter. Despite its height, the plume is little
more than three-quarters of a football field wide (70 yards, or 70 meters).
Image credit: NASA/JPL-Caltech/UA

Thanks to Marc.