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cyclones is in all directions away from the center. The upper levels of a tropical
cyclone feature winds directed away from the center of the storm with an anticyclonic rotation, due to the Coriolis effect. Winds at the surface are strongly cyclonic,
weaken with height, and eventually reverse themselves.
Eye and Inner Core
A strong tropical cyclone will harbour an area of sinking air at the center of circulation. If this area is strong enough, it can develop into an eye. Weather in the eye is
normally calm and free of clouds, although the sea may be extremely violent. The
eye is normally circular in shape, and may range in size from 3 kilometres
(1.9 miles) to 370 kilometres (230 miles) in diameter. Intense, mature tropical
cyclones can sometimes exhibit an inward curving of the eyewall’s top, making it
resemble a football stadium; this phenomenon is thus sometimes referred to as the
stadium effect.
There are other features that either surround the eye, or cover it. The central
dense overcast (CDO) is the concentrated area of strong thunderstorm activity near
the center of a tropical cyclone; in weaker tropical cyclones, the CDO may cover the
center completely. The eyewall is a circle of strong thunderstorms that surrounds the
eye; this is the zone where the greatest wind speeds are found, where clouds reach
the highest, and precipitation is the heaviest. The heaviest wind damage occurs
where a tropical cyclone’s eyewall passes over land. Eyewall replacement cycles
occur naturally in intense tropical cyclones. When cyclones reach peak intensity
they usually have an eyewall and radius of maximum winds that contract to a very
small size, around 10 kilometres (6.2 miles) to 25 kilometres (16 miles). Outer rainbands can organize into an outer ring of thunderstorms that slowly moves inward
and robs the inner eyewall of its needed moisture and angular momentum. When the
inner eyewall weakens, the tropical cyclone weakens (in other words, the maximum
sustained winds weaken and the central pressure rises) The outer eyewall replaces
the inner one completely at the end of the cycle. The storm can be of the same intensity as it was previously or even stronger after the eyewall replacement cycle finishes. The storm may strengthen again as it builds a new outer ring for the next
eyewall replacement.
A tropical cyclone is an almost circular storm that has a low surface pressure at
the centre of its system, high winds that spiral inwards in a counter-clockwise direction, and is usually accompanied by heavy rain. A tropical cyclone’s primary energy
source is the release of the heat of condensation from water vapour condensing at
high altitudes, with solar heating being the initial source for evaporation. Therefore,
a tropical cyclone can be visualized as a giant vertical heat engine supported by
mechanics driven by physical forces such as the rotation and gravity of the Earth. In
another way, tropical cyclones could be viewed as a special type of mesoscale convective complex, which continues to develop over a vast source of relative warmth
and moisture. Condensation leads to higher wind speeds, as a tiny fraction of the
Eye and Inner Core
cyclones is in all directions away from the center. The upper levels of a tropical
cyclone feature winds directed away from the center of the storm with an anticyclonic rotation, due to the Coriolis effect. Winds at the surface are strongly cyclonic,
weaken with height, and eventually reverse themselves.
Eye and Inner Core
A strong tropical cyclone will harbour an area of sinking air at the center of circulation. If this area is strong enough, it can develop into an eye. Weather in the eye is
normally calm and free of clouds, although the sea may be extremely violent. The
eye is normally circular in shape, and may range in size from 3 kilometres
(1.9 miles) to 370 kilometres (230 miles) in diameter. Intense, mature tropical
cyclones can sometimes exhibit an inward curving of the eyewall’s top, making it
resemble a football stadium; this phenomenon is thus sometimes referred to as the
stadium effect.
There are other features that either surround the eye, or cover it. The central
dense overcast (CDO) is the concentrated area of strong thunderstorm activity near
the center of a tropical cyclone; in weaker tropical cyclones, the CDO may cover the
center completely. The eyewall is a circle of strong thunderstorms that surrounds the
eye; this is the zone where the greatest wind speeds are found, where clouds reach
the highest, and precipitation is the heaviest. The heaviest wind damage occurs
where a tropical cyclone’s eyewall passes over land. Eyewall replacement cycles
occur naturally in intense tropical cyclones. When cyclones reach peak intensity
they usually have an eyewall and radius of maximum winds that contract to a very
small size, around 10 kilometres (6.2 miles) to 25 kilometres (16 miles). Outer rainbands can organize into an outer ring of thunderstorms that slowly moves inward
and robs the inner eyewall of its needed moisture and angular momentum. When the
inner eyewall weakens, the tropical cyclone weakens (in other words, the maximum
sustained winds weaken and the central pressure rises) The outer eyewall replaces
the inner one completely at the end of the cycle. The storm can be of the same intensity as it was previously or even stronger after the eyewall replacement cycle finishes. The storm may strengthen again as it builds a new outer ring for the next
eyewall replacement.
A tropical cyclone is an almost circular storm that has a low surface pressure at
the centre of its system, high winds that spiral inwards in a counter-clockwise direction, and is usually accompanied by heavy rain. A tropical cyclone’s primary energy
source is the release of the heat of condensation from water vapour condensing at
high altitudes, with solar heating being the initial source for evaporation. Therefore,
a tropical cyclone can be visualized as a giant vertical heat engine supported by
mechanics driven by physical forces such as the rotation and gravity of the Earth. In
another way, tropical cyclones could be viewed as a special type of mesoscale convective complex, which continues to develop over a vast source of relative warmth
and moisture. Condensation leads to higher wind speeds, as a tiny fraction of the
Eye and Inner Core