Tornadoes occur all over the world, but the United States experiences the most, by far. The US averages around 1,200 tornadoes per year. The next closest is Canada with around 100. CNN Original Series Violent Earth with Liev Schreiber is an in-depth examination into our natural world and its changing climate, featuring scientists, storm chasers, and survivors who experienced harrowing climate events. Violent Earth premieres Sunday at 9pm ET/PT on CNN. | CNN