Scientists Say: Eyewall | Science News for Students

Scientists Say: Eyewall

This is a band of clouds and intense storms that surrounds the eye of a hurricane or cyclone
Jul 1, 2019 — 6:30 am EST
a photo of Hurricane Isable, showing a strong eyewall, taken from the International Space Station

 This is an image of Hurricane Isabel, which hit the United States in 2003. The eye is in the center, surrounded by a band of clouds called the eyewall.  

 Mike Trenchard/Earth Sciences & Image Analysis Laboratory/NASA Johnson Space Center

Eyewall (noun, “EYE-wall”)

This is a ring of intense rain and wind that swirls around the calm center of a tropical cyclone. These powerful storms develop over warm ocean waters just north and south of the equator. They have different names in different regions of the world. Tropical cyclones are “hurricanes” when they occur in the western Atlantic and eastern Pacific north of the equator. They’re “typhoons” in the western Pacific, and “cyclones” south of the equator. All tropical cyclones are destructive storms that have spinning bands of wind and rain. At the center, there’s a calm spot called the eye. Surrounding the eye are the strongest storms of the hurricane or cyclone — the eyewall. The eyewall gets its name because the clouds often pile up higher around the eye.  This creates a wall of clouds around the eye when the storm is seen from above.

When ocean waters get warm, they warm the air above them, too. That warm air rises up, leaving an area with low pressure below it. Cooler air rushes in to the space and begins to warm. As the warm air rises, it cools and forms clouds — which produce wind and rain. The clouds grow as more warm air comes up, and the system begins to spin. The spinning creates a calm eye in the middle of the storm. The clouds around the calm eye will have the fastest spin, piling up clouds around the calm center and creating the eyewall.

In a sentence

Scientists use the wind speeds in the eyewall of a tropical cyclone to judge its intensity.

In this video, a plane flies through the violent eyewall and into the calm eye of a hurricane. The plane shakes and shudders as it goes through the intense storms in the eyewall.
NASA/Goddard Space Flight Center

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Power Words

(more about Power Words)

Atlantic     One of the world’s five oceans, it is second in size only to the Pacific. It separates Europe and Africa to the east from North and South America to the west.

cloud     A plume of molecules or particles, such as water droplets, that move under the action of an outside force, such as wind, radiation or water currents. (in atmospheric science) A mass of airborne water droplets and ice crystals that travel as a plume, usually high in Earth’s atmosphere. Its movement is driven by winds. 

cyclone     A strong, rotating vortex, usually made of wind. Notable examples include a tornado or hurricane.

equator     An imaginary line around Earth that divides Earth into the Northern and Southern Hemispheres.

eye     (in atmospheric sciences) The roughly circular area of comparatively light winds that encompasses the center of a severe tropical cyclone. The eye is either completely or partially surrounded by the eyewall cloud.

eyewall     Also known as a wall cloud, it’s an organized band or ring of cumulonimbus clouds that surround the eye, or light-wind center, of a tropical cyclone.

hurricane     A tropical cyclone that occurs in the Atlantic Ocean and has winds of 119 kilometers (74 miles) per hour or greater. When such a storm occurs in the Pacific Ocean, people refer to it as a typhoon.

Pacific     The largest of the world’s five oceans. It separates Asia and Australia to the west from North and South America to the east.

pressure     Force applied uniformly over a surface, measured as force per unit of area.

tropical cyclone     A strong, rotating storm. These usually form over tropical areas around the equator where the water is warm. Tropical cyclones have strong winds of more than 119 kilometers (74 miles) per hour and usually have heavy rain. Large ones in the Atlantic are known as hurricanes. Those in the Pacific are termed typhoons.

typhoon     A tropical cyclone that occurs in the Pacific or Indian oceans and has winds of 119 kilometers (74 miles) per hour or greater. In the Atlantic Ocean, such storm are referred to as hurricanes