What causes tornadoes to spin?

Tornadoes spin due to the interaction of wind at different altitudes and directions within a thunderstorm. When warm, moist air rises and meets cooler, drier air above, it creates instability and strong updrafts. Winds moving at different speeds and directions cause rotation within the storm, forming a mesocyclone. When this rotation tightens and extends downward, it becomes a tornado. The Coriolis effect plays a minor role in influencing the overall rotation direction in large-scale weather systems.