A hurricane is a tropical cyclone with sustained winds reaching speeds of at least 74 miles per hour, according to The Weather Channel. Hurricanes are classified on a scale of 1 to 5 using the scale Saffir-Simpson hurricane wind scale.
A storm that strengthens over a period of days or weeks is considered a hurricane. The process of hurricane formation starts in the warm, damp air over the tropics, which includes the Caribbean Sea, the Gulf of Mexico, the eastern North Pacific Ocean, the north Atlantic ocean, the east of the International Dateline and the north of the equator. Hurricanes are first categorized as tropical cyclones.
Before a tropical cyclone turns into a hurricane, it passes through four different stages. The first stage is tropical disturbance - a system of clouds, showers and thunderstorms originating in the tropics and staying intact for 24 hours or more. The second stage is tropical depression - a tropical disturbance that develops a closed circulation. The third stage is tropical storm which has maximum sustained one-minute winds of around 39 to 73 miles per hour at an elevation of 10 meters. Finally, the tropical storm becomes a hurricane with sustained one-minute winds of 74 miles per hour at a 10-meter elevation.