Sometimes HiRISE finds something unexpected.
This image was targeted to study knobs in Mars' northern plains, just north of Scandia Crater. The knobs are clearly imaged, but what surprised scientists was a dust devil visible in the south-central part of the image.
As on Earth, dust devils form when ground heated by sunlight warms the air above it. The hot air rises, forming an updraft accompanied by vortical motions. Because warm ground is a requirement, dust devils on Mars generally form in late spring to summer, especially at high latitudes.
This image was taken in early spring (2010), at a latitude of 61 degrees North. No dust devil has been seen this far from the equator at such an early season before.
Photo credit: NASA/JPL/University of Arizona
Note: The location of this dust devil and Scandia Crater are both in the Scandia Colles region of the Vastitas Borealis, and is located in the Diacria Quadrangle. Scandia Crater is located almost due north of Milankovic Crater, which is the most prominent crater in that region.