Dust devil

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Dust devils have an electric heartbeat

When dust whirls into the air in the southwestern desert of the United States, NASA takes interest. The dervishes are miniature versions of the kilometers-tall storms that physically morph the surface of Mars. Now, researchers have measured a basic property of earthly dust devils for the first time: their electric current signature. Physicists created a sensor with a simple 7-centimeter-tall antenna to detect currents carried through the air between a dust devil (such as the one pictured above in the Australian outback) and the sensor. They placed several of these devices in a bone-dry federal land management research site in New Mexico for 40 days in summer 2016. The instruments captured the atmospheric pressures and electrical currents of 11 dust devils that swept directly over one of the sensors or close by. The data revealed positive-to-negative “heartbeat” pulses in the current as the vortices approached and receded, the team reports this month in the Journal of Atmospheric and Solar-Terrestrial Physics. Currents were strongest for the most intense dust devils, as gauged by their internal pressures. Previous studies, using more complicated sensors, had only seen hints of that connection. This information is useful for helping researchers understand how dust devils can affect climate on Earth and Mars. Furthermore, these instruments could show whether electrical charges in powerful dust storms on Mars modify the organic composition of the planet, possibly impacting our ability to detect signs of life.