Today's Image shows an enormous dust devil in Amazonis Planitia on Mars, as taken by HiRISE. The dust devil reached as high at 20km above the surface, roughly the same size as a large terrestrial tornado.
Even though the dust devil reaches so high it only measures 70m in diameter, which allows it to be twisted by high elevation winds giving it a snake-like appearance, like a similar dust devil showcased by Mars Travel.
Dust devils on Mars are similar to tornadoes on Earth, but the biggest difference is that instead of water particles making up the visible outer layer, like in a tornado, dust and sand make up the visible layer. The dust devils on Mars are so much bigger than their counterparts on Earth because the Martian atmosphere is only about 1% as dense as that on Earth.
Clicking on this image will take you to the original, captioned image from HiRISE. I definitely recommend checking it out since they have attached animations showing what it looks like in motion from different angles.