Brian's "Picture of the Month"

IMAGE: Dust Devils over Arizona (Earth)

Dust Devils are almost always visible on the road between Phoenix and Tucson, Arizona in the afternoon. It is difficult to make the journey without seeing at least on in the distance. The desert plain seems perfect for their formation even in cooler temperatures. In the afternoon of Monday 7 May 2012, I photographed [800x600] eight Dust Devils at the same time to the south from high overhead Phoenix. It made me think of the Dust Devils on Mars!

Dust Devils [wiki] are vertical vortices of air which carry dust up into the air from the ground, hence the term "Dust Devils". It is a simple consequence of heated air rising and starting to rotate as it rises. Although it is in some ways similar to a mini-Tornado, it is much smaller and more gentle. They usually appear on clear smooth sunny days.

Scientists were amazed to find Dust Devils on Mars, although with hindsight the desert terrains are very similar. NASA now has quite a few images of them to study, including a giant 12 mile high one seen in 2012. There discovery also explained mysterious marking observed on the Martian surface left by their paths. See images below for more:

The HiRISE Camera [wiki] of the NASA Reconnaissance Obiter captured this Dust Devil 16 Feb 2012. It is about 30 meters across and over half a mile high. More: [], [wiki] The HiRISE Camera [wiki] of the NASA Reconnaissance Obiter captured this sensationally huge Dust Devil 14 March 2012. It is estimated to be 12 miles high (20 km) and 70 meters wide. More: []
The HiRISE Camera [wiki] on the NASA Reconnaissance Obiter took this image 21 Oct 2009 from orbit. It shows numerous twisted trails below on the Martian surface of countless earlier Dust Devils passing by. More: [wiki] A Martian Dust devil passed by NASA's "Spirit" Rover [wiki] 15 May 2005. The full 10 minute sequence can be seen in the animated .gif file below. More: []


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