23 April 2004

Whirlwind season arrives

Photographs, videos and measurements by amateur scientists have made and will continue to make significant contributions to tornado research.

While tornadoes rank among the most devastating and spectacular of natural events, there is another kind of whirlwind that receives much less attention.

This is the dust devil so common in the Southwest United States and in many other regions. They can sometimes even be seen spinning across the summit of Hawaii's Mauna Kea. While they are most common during hot summer days, they can occur anytime when the Sun has heated the ground sufficiently. Many could be seen in late March in West Texas.

Because powerful dust devils on Mars may pose a significant challenge to human exploration of the planet, NASA scientists have taken a serious interest in dust devils. Besides the danger posed by their wind, NASA is interested in electrical activity and magnetic fields created within dust devils that might disrupt communications or even damage electronic circuits.

Dust devils are very common in many regions. Thus, they are attractive natural phenomenon for serious investigations by amateur scientists. The velocity of the spinning vortex and its rate of travel can be determined from sequences of still photographs and videos. Electrical fields within dust devils can be detected and even measured by various kinds of instruments placed near or in the paths of dust devils.

It is sometimes possible to drive along with a dust devil as it scoots across the desert. However, dust devils greatly reduce visibility and sandblast automobile paint. Larger ones might be capable of flipping a light weight vehicle.

Forrest M. Mims III.