A ring of towering thunderstorms where the most severe weather of a cyclone occurs(noun)
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Use "eyewall" in a sentence
"We have what we call eyewall replacement cycles, and the thunderstorms build up and then they collapse, and then the wind speeds increase or decrease along with that."
"And that eye that you see -- these eyes go through what we call eyewall replacements."
"And these bigger, stronger storms will go through these what we call eyewall replacement cycles."