Earth's Furies: Tornadoes

Part of the Earths Furies series: The U.S. is affected by 1,200 tornadoes every year and this phenomenon is growing all over the world. With wind speeds inside their vortex reaching up to 500 km per hour and traveling at the speed of a high-speed train, tornadoes are capable of destroying everything in their path. But how do they start? How can we predict them and minimize their destruction? Is global warming responsible for their increasing frequency?