What causes tornadoes to spin/rotate?

The winds in the tornado themselves are rotating! When a tornado forms, warm winds combine with cooler winds and start rotating horizontally. read more

It is the pressure difference that causes tornadoes to spin. Upon heating the density of air decreases (refer: Kinetic theory of gases - Wikipedia). Hot air becomes relatively lighter than cold air. It, therefore, rises. The remaining space (left by the rising air) is occupied by the cold air nearby. The cold air rushes to occupy the vacancy. read more

Tornadoes and the formation of tornadoes are a popular severe weather topic. Learn what causes a tornado or twister, and the role of severe thunderstorms in their formation. Also introduced are tornado myths, how tornadoes are studied, and where the most severe storms are located. read more

The direction in which a tornado twists depends a lot upon which hemisphere you're in. In general, most tornadoes in the northern hemisphere rotate cyclonically, or counter-clockwise. Only around five percent of tornadoes in the northern hemisphere rotate clockwise, or anti-cyclonically. In the southern hemisphere, however, most tornadoes rotate clockwise. read more