Hurricanes form over the Atlantic or Pacific Ocean near the Equator when the surrounding water is at least 80 degrees Fahrenheit, according to SciJinks. The term "hurricane" typically refers to tropical storms in the Western Hemisphere, but similar weather conditions occur worldwide and are known as tropical cyclones or typhoons.
Scientists understand the necessary conditions for hurricanes to develop, but they haven't determined exactly how these storms form. As wind travels over a warm ocean surface, the water changes to vapor, cools down and condenses into droplets to form cumulonimbus clouds. A tropical disturbance forms as the clouds compound into rotating columns and cause thunderstorms. Gradual changes in air pressure make the storm winds spin faster and climb higher, picking up ocean water as they move towards land.