Anatomy of a tropical cyclone

In an earlier post, we took a look at the differences between hurricanes, typhoons, and cyclones. All three names refer to the same weather phenomenon, a tropical cyclonic storm, and the specific name depends only upon where the storm happens to be located. Hurricanes, typhoons, and cyclones all have the same basic structure.

At the center of a hurricane is the eye, which can be up to 40 miles (65 km) in diameter. Within this relatively calm, even sunny, eye of the storm, air falls from the tropopause (the upper reaches of the troposphere) toward the ocean’s surface. As it does so, it compresses and warms, which inhibits the formation of clouds.

The cloudy boundary between the eye and the storm’s rain bands is called the eyewall, which is the most violent and destructive part of the hurricane. The diameter of the eyewall often increases with height above the ocean’s surface, creating a phenomenon called the stadium effect, named for its resemblance to an open-air sporting venue. The eyewall is also the tallest point of the storm, reaching all the way to the tropopause, roughly 50,000 feet in altitude in the tropics.

Moving radially outward from the eyewall, a series of rain bands spirals around the eye, decreasing in both height and intensity with distance from the storm’s center. Each rain band exhibits its own convective currents, pulling moisture and warmth from the ocean and pushing it toward the top of the storm. This warmth and moisture promotes additional rain, which, in turn, further enhances entrainment of warmth and moisture, creating a powerful self-sustaining storm.

While hurricanes provide enough destructive power in and of themselves, such storms can also spawn tornadoes, further amplifying a storm’s potential to inflict damage.

Hurricanes are complex weather systems, but such storms’ winds follow predictable patterns. A sophisticated understanding of these weather systems enables scientists and engineers to create built environments that can weather even the most powerful storms.