National Geographic in tornado lab

A crew filming a documentary for the National Geographic Channel sets up a shot under the big fan of Iowa State University's tornado simulator. The crew worked with Iowa State researchers Partha Sarkar, Fred Haan and Bill Gallus to create laboratory tornadoes for the documentary. The crew is documenting the March 27, 1994, tornado near Piedmont, Ala., that hit the Goshen United Methodist Church and killed 20 people.