Today's Image of Mars comes from HiRISE and shows the snaking shadow of a huge dust devil in Amazonis Planitia. The length of this shadow indicates that this particular dust devil is approximately 800m (half a mile) in height.
The reason that it is so serpentine is that at about 250m above the surface a westerly breeze pushed the top of the dust devil to the east. This particular dust devil is about 30m in diameter.
What is extraordinary about this dust devil is that it formed during a time of year when Mars is furthest from the Sun. Just as on Earth, the Sun plays a large role in the winds on Mars, but it seems that even when Mars is further away from the Sun, it still has numerous dust devils!
Clicking on this image will take you to the original, captioned image from HiRISE, from where you can view the high resolution images!