Susan J. Tweit is a scientist who evolved into an award-winning writer and radio commentator. She is the author of five books for adults, including Barren, Wild, & Worthless: Living in the Chihuahuan Desert, personal stories about the history and natural history of Southern New Mexico, The Great Southwest Nature Factbook, a browser's guide to nature in the Southwest, from A to Z, and Seasons in the Desert: A Naturalist's Notebook, from Chronicle books. She has also written two children's books, Meet the Wild Southwest: Land of Hoodoos & Gila Monsters (Alaska Northwest Books) and City Foxes, a picture book which was named one of the Outstanding Science Books for Children for 1998.
Her "Wild Lives" radio commentaries are heard three times weekly on KRWG-FM, Southern New Mexico public radio, and her columns run in the Las Cruces Sun News. Susan's essays and stories have appeared in Harrowsmith Country Life, New Mexico, Sierra, Cricket, Bloomsbury Review, and other magazines. She is the co-founder of Las Cruces' wildly popular - and fun - Border Book Festival. She is currently living in Colorado with her husband, Richard Cabe, and dog, Perdida Imelda.
Susan is a popular public speaker and leader of workshops. Her stories of our natural and human history have captivated a wide variety of audiences, including school classes, workshops, banquets, and professional meetings. As Bloomsbury Review put it, she brings the precision of a scientist and the passion of a poet, and is able to refocus readers' vision and ignite their imaginations.
Susan has a new web site! She invites you to come visit. Her books are available there, at local bookstores, or on-line through http://BarnesandNoble.com and http://Amazon.com (search by author for Susan Tweit).
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Dust devils certainly seem like magic, springing up suddenly from the hot ground, taking pale form from the soil they carry, and dancing whichever way they will. Creatures of warm climates and dry country, dust devils are children of the sun.
They form most often in spring and summer when the sun beats full strength on the soil, heating the ground surface as much as 80 degrees hotter than the air. Like a hot plate or an electric stove, the soil surface radiates energy into the air that it touches, heating a thin layer near the ground. Soon a bubble of this extremely hot and now less dense air floats upward. More hot surface air rushes in to take its place, developing a thermal, or rising stream of hot air, habitat for soaring hawks, vultures, and glider pilots.
But a thermal remains just that until an eddy, or area of turbulence, in the air gives it a whirl. Once spinning, it sucks in more hot air and whirls faster. The spinning column remains invisible until it vacuums up surface detritus: dry soil, tumbleweeds, trash, or even, if its winds grow strong enough, a kangaroo rat or two. Thus is born a dust devil, a desert dancer.
Dust devils usually grow no larger than 20 feet across and 100 feet tall. Borne on 20- to 0-mile-per-hour-winds, they whirl only for a few minutes before running out of hot air. However, the sizzling summer temperatures of the West's hottest, lowest elevation places like Death Valley, California, or the desert around Phoenix, Arizona, sometimes spawn giant dust devils that tower a half-mile high and pack winds whirling as fast as 90 miles per hour, capable of tearing off roofs and collapsing walls.
Nevada's Gosiute Indians believed that they were born of the wind-swirled dust, and that whirlwinds embodied their ancestors' spirits. After riding through a whirlwind on my bike the other day, and arriving home wind-tossed and plastered with grit, I'm inclined to believe those who ascribe dust devils to Old Man Coyote, who, it is said, stirs them up for mischief. I could swear I heard Coyote laughing when that whirlwind hit me.