A hurricane, also called a tropical cyclone, is the most powerful storm that forms on Earth. A hurricane forms over warm ocean water. As it grows in size and intensity, its powerful winds begin rotating around a center like water going down a drain. Because of the physics phenomenon known as the Coriolis Effect, hurricanes that form in the Northern Hemisphere feature winds that move counterclockwise, while those that form in the southern hemisphere feature winds that move clockwise. In the center of a powerful hurricane (called the eye), air may sink rather than rise, which suppresses cloud formation, leading to calm skies and wind. The eye of a hurricane can be up to 240 miles in diameter, but is normally between 20 and 40 miles in diameter. The clouds on the edge of the eye form the eyewall of the hurricane, which typically feature the hurricane’s strongest winds, highest clouds, and fiercest precipitation.

When its winds reach 39 miles per hour, it becomes a tropical storm, and as the storm continues to expand, and its winds reach 74 miles per hour, it is a hurricane or tropical cyclone where it will receive a name (like Hurricane Katrina). By this time, the massive storm is 50,000 feet high and 125 miles across. Winds from the hurricane can extend hundreds of miles from the center or “eye” of the hurricane, which itself may be 30 miles across. The most powerful hurricanes can sustain winds of over 156 miles per hour. When hurricanes hit land, they cause massive damage, storm surges, major wind damage, rogue waves, and flooding. Once they hit land, however, they quickly weaken as they are longer being powered by warm ocean water.