A hurricane is a cyclone or wind of great force that forms a whirlwind and turns in large circles. For a cyclone to be classified as a hurricane it must at least have a rotation speed of 119 km/h or 74 mps. A hurricane originates in the tropics and since its formation begins to expand its diameter and speed, generally following this cycle: tropical depression, with a speed less than 63 km/h or 39 mph < tropical storm (64 km/h or 40 mph) < hurricane, with a speed equal to or greater than (74 – km/h or 39 mph). Hurricanes are measured according to their speed and the damage caused, generally using the following scale: The five categories of the Saffir-Simpson wind scale: Category 1: 119-153 km/h – 74-95 mph / No damage to building structures Category 2: 154-177 km/h – 96-110 mph / Damage to roofs, doors and windows Category 3: 178-209 km/h – 111-130 mph / Structural damage in small buildings Category 4: 210-249 km/h – 131- 155 mph / Generalized damage to protective structures Category 5: 250+ km/h – 156+ mph / Complete roof destruction in some buildings.