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Physical structure






PLAN

1. Foreword

2. Physical structure

  1. Formation
  2. Effects
  3. Notable tropical cyclones
  4. Related cyclone types
  5. In popular culture
  6. References

TROPICAL CYCLONE

 

 

Hurricane Isabel (2003) as seen from orbit duringExpedition 7 of the International Space Station. The eye, eyewall and surrounding rainbands that are characteristics of tropical cyclones are clearly visible in this view from space.

A tropical cyclone is a storm system characterized by a low-pressure center surrounded by a spiral arrangement of thunderstorms that produce strong winds and heavy rain. Tropical cyclones strengthen when water evaporated from the ocean is released as the saturatedair rises, resulting in condensation of water vapor contained in the moist air. They are fueled by a different heat mechanism than other cyclonic windstorms such as nor'easters, European windstorms, and polar lows. The characteristic that separates tropical cyclones from other cyclonic systems is that at any height in the atmosphere, the center of a tropical cyclone will be warmer than its surroundings; a phenomenon called " warm core" storm systems.

The term " tropical" refers both to the geographical origin of these systems, which usually form in tropical regions of the globe, and to their formation in maritime tropical air masses. The term " cyclone" refers to such storms' cyclonic nature, with counterclockwise wind flow in the Northern Hemisphere and clockwise wind flow in the Southern Hemisphere. The opposite direction of the wind flow is a result of theCoriolis force. Depending on its location and strength, a tropical cyclone is referred to by names such as hurricane (/ˈ hʌ rɨ keɪ n/, /ˈ hʌ rɨ kə n/), typhoon (/taɪ 'fuː n/), tropical storm, cyclonic storm, tropical depression, and simply cyclone.

While tropical cyclones can produce extremely powerful winds and torrential rain, they are also able to produce high waves, damagingstorm surge, and tornadoes. They develop over large bodies of warm water, and lose their strength if they move over land due to increased surface friction and loss of the warm ocean as an energy source. This is why coastal regions can receive significant damage from a tropical cyclone, while inland regions are relatively safe from receiving strong winds. Heavy rains, however, can produce significant flooding inland, and storm surges can produce extensive coastal flooding up to 40 kilometres (25 mi) from the coastline. Although their effects on human populations can be devastating, tropical cyclones can relieve drought conditions. They also carry heat energy away from the tropics and transport it toward temperate latitudes, which makes them an important part of the global atmospheric circulationmechanism. As a result, tropical cyclones help to maintain equilibrium in the Earth's troposphere, and to maintain a relatively stable and warm temperature worldwide.

Many tropical cyclones develop when the atmospheric conditions around a weak disturbance in the atmosphere are favorable. The background environment is modulated by climatological cycles and patterns such as the Madden-Julian oscillation, El Niñ o-Southern Oscillation, and the Atlantic multidecadal oscillation. Others form when other types of cyclones acquire tropical characteristics. Tropical systems are then moved by steering winds in the troposphere; if the conditions remain favorable, the tropical disturbance intensifies, and can even develop an eye. On the other end of the spectrum, if the conditions around the system deteriorate or the tropical cyclone makes landfall, the system weakens and eventually dissipates. It is not possible to artificially induce the dissipation of these systems with current technology.

 

PHYSICAL STRUCTURE

Typhoon Nabi as seen from the International Space Station, on September 3, 2005.

All tropical cyclones are areas of low atmospheric pressure in the Earth's atmosphere. The pressures recorded at the centers of tropical cyclones are among the lowest that occur on Earth's surface at sea level.[1] Tropical cyclones are characterized and driven by the release of large amounts of latent heat of condensation, which occurs when moist air is carried upwards and its water vapor condenses. This heat is distributed vertically around the center of the storm. Thus, at any given altitude (except close to the surface, where water temperature dictates air temperature) the environment inside the cyclone is warmer than its outer surroundings.


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