Cross section through a hurricane showing the locations of the eye, eyewall, and rainbands. Arrows show the direction of air movement within the storm. Air spirals upward at the eyewall and sinks in the center of the eye. Click on image for full size (98 Kb) Courtesy of NOAA National Weather Service

At the center of a fierce tropical storm, there is a small area where the weather is calm, the sky is clear, and the winds are just light breezes. This area is called the eye of the storm.

As a hurricane strengthens and wind speeds increase, an eye begins to form at the center of the storm. Usually this happens once winds reach about 80 mph. The eye is usually circular when viewed from above, and about 20 to 40 miles is diameter. It is roughly cylinder shape in cross section, extending through the center of the storm like a chimney. Air from above the storm sinks down in the center of the eye.

Surrounding the eye is the eyewall, which is the most violent part of a hurricane. The eyewall is a ring of dense cumulonimbus clouds – thunderstorm clouds. There, the strongest winds in the hurricane are found and warm, moist air is pulled into the storm, rising along the eyewall where it cools and forms more cumulonimbus clouds.