A cyclone is a powerful spinning storm system with winds that rotate around a center of very low air pressure.

When warm, moist air rises rapidly, it creates an area of low pressure that pulls in more air from all directions. Because Earth is rotating, these winds don't blow straight in: they curve and begin spiraling. In the Northern Hemisphere, cyclone winds spin counterclockwise, while in the Southern Hemisphere they spin clockwise.

Meteorologists use cyclone as a general term for various rotating storm systems. In the Indian Ocean and South Pacific, tropical cyclones are simply called cyclones. The exact same type of storm is called a hurricane in the Atlantic Ocean and a typhoon in the Western Pacific. These are all cyclones, just with different regional names. The most destructive cyclones have wind speeds exceeding 150 miles per hour and can cause catastrophic damage when they strike land.

Scientists also use the word for winter storms and other weather systems with rotating winds, even if they're not as dramatic as tropical cyclones. When your local weather forecaster mentions a “low-pressure system,” they're often talking about a type of cyclone, though usually a much gentler one than the tropical storms that make headlines.