Tornadoes form after clouds darken and a funnel forms within minutes. Strong tornadoes can reach over 300 mph and suck up anything in their path, dropping debris after the tornado passes. While smaller tornadoes, known as sisters of tornadoes, are less powerful than main tornadoes they can still be dangerous and carry objects like cars. Tornadoes are rated on the Fujita scale from F1 to F5 based on damage caused, with F5 being the most severe and destructive.