Eye wall
Topic: Air Masses, Fronts, Cyclones and Thunderstorms · NCERT: Class 11, Ch 9 "Atmospheric Circulation and Weather Systems"
Meaning
The eye wall is a ring of towering cumulonimbus clouds (tall, dark thunderclouds) around the calm eye of a tropical cyclone. Here, warm moist air spirals upward all the way to the tropopause, the top of the lowest layer of the atmosphere. As the water vapour turns into cloud, it gives out heat, and this heat drives the storm. So the eye wall has the strongest winds, up to about 250 km/h, and torrential rain. It is the most dangerous part of a cyclone.
Example
In the Odisha super cyclone of 1999, the eye wall crossed the coast near Paradip with winds over 250 km/h. It caused the worst destruction of the storm.
Don't confuse with
- Eye: the calm, often clear centre with sinking air. The eye has the lowest pressure, but the eye wall has the strongest winds.
- Rain bands: the outer spiral bands of cloud, which give bursts of rain but weaker winds than the eye wall.