Neil Ward, a native Oklahoman, did experiments with tornado models in the early 1950s and the 1960s. Here, the miniature tornado twists with a sinuous ribbon shape. What's going on? Well, air flows in through the open sides. As it does, the vertical fins (best seen to the left of the tornado) spin around, causing the inrushing air to spin as well. A heated chimney then causes the air to rise through the small, adjustable opening pictured in the top of the model. With the help of cigarette smoke, which is used as a tracer, a "tornado" becomes visible.