The Anatomy of a Hurricane

Hurricanes, they are the most severe and destructive category of a tropical cyclone. Spanning 300 miles or more with winds that can exceed 155 mph, this meteorological phenomenon is not only devastating, it also has a unique anatomy unlike any other storm. The structure of a hurricane consists of three main parts; rainbands on the outer edges, the eyewall, and the eye.

The outer portion of a hurricane consists of bands of showers and thunderstorms known as rainbands. These bands can extend a few hundred miles from the center of the storm, and can range in width from just a few miles to tens of miles and are about 50 to 300 miles in length. The size of a hurricane isn’t necessarily a determining factor of it’s intensity. Hurricane Andrew in 1992, for example, had rainbands reaching only 100 miles from the eye and is the second most destructive hurricane in U.S. history. The rainbands spiral slowly in a counterclockwise direction. There can be relatively calm weather between bands with high wind gusts and heavy downpours in the individual rainbands.

The strongest winds and heaviest precipitation within the storm occurs at the eyewall, a dense wall of thunderstorms surrounding the eye of the storm. Changes in wind speed, which is an indicator of the storm’s intensity, are caused by changes in the structure of the eye and the eyewall. As the eyewall passes over land, the heaviest wind damage occurs. Eyewall replacement is a natural occurrence within intense tropical cyclones. During this replacement process, outer rings of thunderstorms move slowly inward stealing moisture from the inner eyewall. As the inner eyewall weakens, the tropical cyclone weakens and the outer eyewall replaces the inner one at the end of the cycle. Upon completion of eyewall replacement, the storm can be of the same intensity or even stronger.

The eye of the storm develops from an area of sinking air at the center of the tropical cyclone. The eye is normally calm and free of clouds. It is usually takes on a circular shape and can range from about 20 to 40 miles across, and can grow and shrink in size. Some more intense, mature tropical cyclones may exhibit the stadium effect. This phenomenon is a result of the inward curving of the top of the eyewall, resembling a football stadium.

Typically, the right side of a hurricane is the most dangerous with its presence of storm surges, tornadoes, and winds. The speed and path of a hurricane depend on oceanic and atmospheric interactions making it difficult to predict the speed and direction a hurricane may travel.