Physics Buzz

It's already possible to do some really extraordinary things with sound waves, like levitating small particles and manipulating them in-air  (useful for caustic chemistry reactions) but we're about to see another tool added to the sonic utility belt: spin. Scientists from Nanjing University in China have recently created a passive device that, for the first time, easily allows planar sound waves to be converted into corkscrew-shaped spiral waves without requiring elaborate geometric arrangements of sound sources.

Combine a firestorm with some tumbleweeds and a dust devil and you get a massive vortex that’s unlike anything you’ve seen before. Watch as fire experts in Rocky Mountain, Arkansas come face-to-face with a smoky, debris-littered dust devil moving across a burning field. Dust devils are not nearly as powerful or destructive as tornados, but that does not stop the cautious men in the video from keeping their distance. Dust devils form when hot air near the ground finds a section of low-pressure cool air above it. When this happens, the hot air quickly rises and under certain conditions it can start to rotate, forming a vertical column. Usually, the air near the surface heats up due to radiation from the Sun. But it looks like what happened in this scenario is that the heat from the controlled fire initiated the vortex. And as the dust devil grew, it began collecting nearby tumbleweeds in the process – the large, black, floating clumps.