Scientific American: A powerful tornado as much as three-kilometers wide devastated the Oklahoma City suburb of Moore on May 20. The twister reportedly boasted winds above 300 kilometers-per-hour as it tore through homes and schools, leaving a path of large-scale destruction and killing dozens of people, including many children. Oklahoma is ground zero for tornadoes for geographic reasons. The state is located precisely where warm air from the Gulf of Mexico collides with colder weather from the west and north. Many...