Cyclical new eyewall formation

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Typhoon Amber undergoes a new eyewall formation. Inner and outer eyewalls are easy to distinguish.

Cyclic Eyewall neoplasms (Engl. Eyewall replacement cycles ) occur mostly in strong tropical cyclones of category 3 or more on the Saffir-Simpson Hurricane Wind Scale . When tropical cyclones reach this strength and the eyewall is contracting or small enough, some of the outer rainbands may intensify and form a second ring of strong thunderstorms (a second eyewall) around the center of the storm. This moves slowly towards the center and thus removes important moisture and, above all, the angular momentum from the inner eyewall . Since the strongest winds of a tropical cyclone are in the eyewall, it weakens during the cycle. However, when the cycle is complete and the outer eyewall has replaced the inner one, the storm can intensify again. With the new, larger eyewall obtained in this way, the wind field of the storm also increases.

Most strong tropical cyclones go through at least one such cycle, and the strength of the storm can vary greatly.

literature

  • Jack Williams: The AMS Weather Book: The Ultimate Guide to America's Weather . The University of Chicago Press, 2009.