I was driving in Oak Lawn on June 1. It was a beautiful day, not a cloud in the sky. Suddenly there was a sort of small rotation blowing leaves and then two garbage cans were lofted 20 feet into the air. This all came and went in a few seconds. What was it that I witnessed?
You witnessed a dust devil, an atmospheric whirlwind that resembles a small tornado, but formed by completely different mechanisms. Rotating either clockwise or counterclockwise, dust devils form on sunny, relatively windless and warm days, usually over expanses of dirt or pavement. Hot air at the surface rises into cooler air above, forming a column several feet in diameter and climbing 50 feet, or more, into the air. Wind speeds can surpass 50 m.p.h., though usually less. Dust devils are rare here, but occur frequently in desert areas.