A cyclone is a low-pressure area. A cyclone's center (often known in a mature tropical cyclone as the eye), is the area of lowest atmospheric pressure in the region. Near the center, the pressure gradient force (from the pressure in the center of the cyclone compared to the pressure outside the cyclone) and the force from the Coriolis effect must be in an approximate balance, or the cyclone would collapse on itself as a result of the difference in pressure. Because of the Coriolis effect, the wind flow around a large cyclone is counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere. In the Northern Hemisphere, the fastest winds relative to the surface of the Earth therefore occur on the eastern side of a northward-moving cyclone and on the northern side of a westward-moving one; the opposite occurs in the Southern Hemisphere. In contrast to low pressure systems, the wind flow around high pressure systems are clockwise (anticyclonic) in the northern hemisphere, and counterclockwise in the southern hemisphere. There are a number of structural characteristics common to all cyclones. The boundary layer inflow, eyewall, currus shield, rainbands, and upper tropospheric outflow are found in all tropical depressions and tropical storms. As these storms become more intense, a clear central eye becomes visible from satellite.
There are a number of structural characteristics common to all cyclones. The boundary layer inflow, eyewall, currus shield, rainbands, and upper tropospheric outflow are found in all tropical depressions and tropical storms. As these storms become more intense, a clear central eye becomes visible from satellite.
A well developed tropical cyclone has a particular shape. The tropical cyclones vary greatly in size, however all have particular shape and structure.
A low pressure core around which the tropical cyclone rotates. The low pressure at the center of the tropical cyclone is amongst the lowest that occur on Earth's surface at sea level. For some cyclones the pressure dips below 900 mb, and these are the most devastating tropical cyclones.
At the center of the cyclones, the temperature is greater than the surroundings. A warm core is formed as a result of condensation of the upward rising moist air, which releases latent heat of condensation.
All cyclones have a Central Dense Overcast (CDO). A CDO is a dense shield that contains the eye and the eyewall of the tropical cyclone. The classic tropical cyclone contains a symmetrical CDO, i.e. it is perfectly circular and round on all sides. This is the zone where maximum activity occurs.
It is composed of large number of thunderstorms arranged in a pinwheel formation with thick clouds spiraling around the storm center popularly known as the "eye".
An eye of the cyclone is most remarkable and characteristic feature of all tropical cyclone. It is the area of sinking air at the center of circulation. The eye is filled with low- and mid-level clouds (a filled eye), or it is obscured by the central dense overcast. However, it is characterized by clear skies and calm weather. It is circular in shape and in size ranges from 8 - 200 km.
Surrounding the eye is the eyewall, a ring of very cold clouds. It is an area that features maximum wind speed, heaviest rainfall and greatest height. It is responsible for the maximum damage caused by a cyclone.
At the upper level of tropical cyclone winds move away from the center resulting in anticyclonic rotation.