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A tropical cyclone is a large cyclonic swirling system that generates enormous energy, however there movements,intensity and organisation are controlled by simple conditions. Organization is controlled by Wind shear, Intensity by [[Sea Surface Temperatures]] and movements by Steering winds.

==Steering winds==
Although tropical cyclones are large systems generating enormous energy, their movements over the Earth's surface are controlled by large-scale winds&mdash;the streams in the Earth's atmosphere. The path of motion is referred to as a tropical cyclone's ''track'' and has been analogized by Dr. Neil Frank, former director of the [[National Hurricane Center]], to "leaves carried along by a stream".<ref name = "AOML FAQ G6">{{cite web | author = [[Atlantic Oceanographic and Meteorological Laboratory]], Hurricane Research Division | title = Frequently Asked Questions: What determines the movement of tropical cyclones?|publisher = [[NOAA]] | accessdate = 2006-07-25 | url = http://www.aoml.noaa.gov/hrd/tcfaq/G6.html}}</ref>

Tropical systems, while generally located [[equator]]ward of the 20th parallel, are steered primarily westward by the east-to-west winds on the equatorward side of the [[subtropical ridge]]—a persistent high pressure area over the world's oceans.<ref name = "AOML FAQ G6"/> In the tropical North Atlantic and Northeast Pacific oceans, [[trade winds]]—another name for the westward-moving wind currents—steer [[tropical waves]] westward from the African coast and towards the Caribbean Sea, North America, and ultimately into the central Pacific ocean before the waves dampen out.<ref name = "AOML FAQ A4">{{ cite web | author = [[Atlantic Oceanographic and Meteorological Laboratory]], Hurricane Research Division | title = Frequently Asked Questions: What is an easterly wave? | publisher = [[NOAA]] | accessdate = 2006-07-25 | url = http://www.aoml.noaa.gov/hrd/tcfaq/A4.html}}</ref> These waves are the precursors to many tropical cyclones within this region.<ref name="MWR Avila 1995"/> In the Indian Ocean and Western Pacific (both north and south of the equator), tropical cyclogenesis is strongly influenced by the seasonal movement of the [[Intertropical Convergence Zone]] and the [[monsoon trough]], rather than by easterly waves.<ref name="MILLER7">{{cite web | author = DeCaria, Alex | publisher = [[Millersville University of Pennsylvania|Millersville University]] | url = http://snowball.millersville.edu/~adecaria/ESCI344/esci344_lesson05_TC_climatology.html | title = Lesson 5 – Tropical Cyclones: Climatology. | work = ESCI 344 – Tropical Meteorology | year = 2005 | accessdate = 2008-02-22}}</ref> Tropical cyclones can also be steered by other systems, such as other [[low pressure systems]], [[high pressure systems]], [[warm front]]s, and [[cold front]]s.

==Coriolis effect==
[[Image:Cyclone_Monica.png|thumb|250px|right|Infrared image of a powerful southern hemisphere cyclone, [[Cyclone Monica|Monica]], near peak intensity, showing [[clockwise]] rotation due to the [[Coriolis effect]]]]
The Earth's rotation imparts an acceleration known as the ''[[Coriolis effect]]'', ''Coriolis acceleration'', or colloquially, ''Coriolis force''. This acceleration causes cyclonic systems to turn towards the poles in the absence of strong steering currents.<ref name="Paleoglossary Cn-Cz">{{cite web | author = Baum, Steven K. | url = http://stommel.tamu.edu/~baum/paleo/paleogloss/node10.html | title = The Glossary: Cn-Cz. | work = Glossary of Oceanography and the Related Geosciences with References | publisher = [[Texas A&M University]] | date = 20 January 1997 | accessdate = 2006-11-29}}</ref> The poleward portion of a tropical cyclone contains easterly winds, and the Coriolis effect pulls them slightly more poleward. The westerly winds on the equatorward portion of the cyclone pull slightly towards the equator, but, because the Coriolis effect weakens toward the equator, the net drag on the cyclone is poleward. Thus, tropical cyclones in the [[Northern Hemisphere]] usually turn north (before being blown east), and tropical cyclones in the [[Southern Hemisphere]] usually turn south (before being blown east) when no other effects counteract the Coriolis effect.<ref name="BritTCtrackcoriolis"/>

The Coriolis effect also initiates cyclonic rotation, but it is not the driving force that brings this rotation to high speeds – that force is the [[heat of condensation]].<ref name="NOAA Question of the Month"/>

==Interaction with the mid-latitude westerlies==
[[Image:Tropical Cyclone Tracks.jpg|thumb|left|Image depicts various types of storm tracks]] [[Image:Ioke 2006 track.png|thumb|right|250 px|Storm track of [[Hurricane Ioke|Typhoon Ioke]], showing recurvature off the Japanese coast in [[2006 Pacific hurricane season|2006]]]]Tropical Cyclone recurvature is the change in a tropical cyclone's track from westward and poleward to eastward and poleward. An recurving Tropical Cyclone is defined as poleward movement of a Tropical Cyclone from the deep easterlies of the tropics into the strong upper tropospheric westerlies of the mid-latitudes. This motion is often seen with Tropical Cyclones that are moved northwestward around the western portion of a subtropical ridge and then turn poleward and eastward under the influence of the mid-latitude westerlies. Also  some recurving TCs can be further classified with respect to how rapidly they recurve. <ref>U. S. Navy. [http://www.nrlmry.navy.mil/~chu/chap4/se200.htm Section 2: Tropical Cyclone Motion Terminology.] Retrieved on [[2007-04-10]].</ref> A typhoon moving through the Pacific Ocean towards Asia, for example, will recurve offshore of Japan to the north, and then to the northeast, if the typhoon encounters southwesterly winds (blowing northeastward) around a low-pressure system passing over China or [[Siberia]]. Many tropical cyclones are eventually forced toward the northeast by [[extratropical cyclone]]s in this manner, which move from west to east to the north of the subtropical ridge. An example of a tropical cyclone in recurvature was [[Hurricane Ioke|Typhoon Ioke]] in 2006, which took a similar trajectory.<ref name="CPHC Ioke">{{cite web | url = http://www.prh.noaa.gov/cphc/summaries/2006.php#ioke | title = Hurricane Ioke: 20-27 August 2006 | date = May 2007 | year = 2007 | accessdate = 2007-06-09 | author = Powell, Jeff, et al. | work = 2006 Tropical Cyclones Central North Pacific | publisher = [[Central Pacific Hurricane Center]]}}</ref>

==Landfall==
{{See also|List of notable tropical cyclones|Tropical cyclogenesis#Unusual areas of formation|l2=Unusual areas of tropical cyclone formation}}
[[Image:Hurricane rita annotated.jpg|thumb|300px|right|An Image depicting Hurricane Rita's Center and where landfall would occur if an island was at the eye.]]
Officially, ''[[landfall (meteorology)|landfall]]'' is when a storm's center (the center of its circulation, not its edge) crosses the coastline.<ref name="NHC glossary"/> Storm conditions may be experienced on the coast and inland hours before landfall; in fact, a tropical cyclone can launch its strongest winds over land, yet not make landfall; if this occurs, then it is said that the storm made a ''direct hit'' on the coast.<ref name="NHC glossary"/> Due to this definition, the landfall area experiences half of a land-bound storm by the time the actual landfall occurs. For emergency preparedness, actions should be timed from when a certain wind speed or intensity of rainfall will reach land, not from when landfall will occur.<ref name="NHC glossary">{{cite web | author = [[National Hurricane Center]] | url = http://www.nhc.noaa.gov/aboutgloss.shtml | year = 2005 | title = Glossary of NHC/TPC Terms | accessdate= 2006-11-29 | publisher = [[National Oceanic and Atmospheric Administration]]}}</ref>

==Multiple storm interaction==
{{Main|Fujiwhara effect}}
When two cyclones approach one another, their centers will begin orbiting cyclonically about a point between the two systems. The two vortices will be attracted to each other, and eventually spiral into the center point and merge. When the two vortices are of unequal size, the larger vortex will tend to dominate the interaction, and the smaller vortex will orbit around it. This phenomenon is called the Fujiwhara effect, after [[Sakuhei Fujiwhara]].<ref>{{cite web |url=http://www.usatoday.com/weather/wfujiwha.htm |title=Fujiwhara effect describes a stormy waltz |accessdate=2008-02-21 |work=[[USA Today]] |publisher= |date= }}</ref>

==See also==
{{Portal|Tropical cyclones}}
* [[Tropical cyclone]]
* [[Hurricane Alley]]
* [[Hypercane]]
* [[List of wettest tropical cyclones by country]]
* [[Secondary flow#Tropical cyclones|Secondary flow in tropical cyclones]]

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;Annual seasons
* [[List of Atlantic hurricane seasons]] ([[{{CURRENTYEAR}} Atlantic hurricane season|current]])
* [[List of North Indian Ocean cyclone seasons]] ([[{{CURRENTYEAR}} North Indian Ocean cyclone season|current]])
* [[List of Pacific hurricane seasons]] ([[{{CURRENTYEAR}} Pacific hurricane season|current]])
* [[List of Pacific typhoon seasons]] ([[{{CURRENTYEAR}} Pacific typhoon season|current]])
* [[List of Southern Hemisphere tropical cyclone seasons]] ([[{{#ifexpr:{{#time:n}}>6|{{#time:Y}}-{{#time:y|+1 year}}|{{#time:Y|-1 year}}-{{#time:y}}}} Southern Hemisphere tropical cyclone season|current]])
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;Forecasting and preparation
* [[Catastrophe modeling]]
* [[Hurricane Engineering]]
* [[Hurricane preparedness]]
* [[Hurricane proof building]]
* [[Tropical cyclone watches and warnings]]
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{{Cyclones}}

==References==
{{Reflist|2}}

==External links==
{{Commons category|Tropical cyclones}}

;Learning resources
* [http://www.ncdc.noaa.gov/oa/esb/?goal=weather&file=events/hurricane/ Economic Costs of Hurricanes and associated Economic Benefits from Improved Forecasting]
* [http://www.fema.gov/kids/hurr.htm FEMA for Kids: Hurricanes]
* {{cite web|url= http://www.nhc.noaa.gov/marinersguide.pdf |title=Mariner's Guide for Hurricane Awareness }}&nbsp;{{small|(1.23&nbsp;[[Mebibyte|MiB]])}}
* [http://www.researchchannel.org/prog/displayevent.aspx?rID=19645&fID=345 Is Global Climate Change Affecting Hurricanes?]
* [http://www.pbs.org/wgbh/nova/teachers/viewing/3204_02_nsn.html NOVA science now: Hurricanes]
* [http://www.edu4hazards.org/hurricane.html Surviving a hurricane – A guide for children and youth]
* [http://www.aoml.noaa.gov/hrd/tcfaq/A1.html Summary of cyclone terminology from NOAA FAQ]
* [http://www.solar.ifa.hawaii.edu/Tropical/tropical.html Tropical Storms Worldwide] – by Hawaii University
* [http://www.bom.gov.au/bmrc/pubs/tcguide/ch1/ch1_3.htm WMO guide on cyclone terminology]
* [http://severe.worldweather.org/ World Meteorological Organization Severe Weather Information Center] – Shows all current tropical systems worldwide and their tracks
;Regional specialised meteorological centers
* [http://www.atl.ec.gc.ca/weather/hurricane/index_e.html Canadian Hurricane Centre] - Canadian Maritimes
* [http://www.cdera.org/ Caribbean Disaster Emergency Response Agency] - Caribbean region
* [http://www.stormcarib.com/ Caribbean Hurricane Network] - Caribbean region
* [http://www.prh.noaa.gov/hnl/cphc/ Central Pacific Hurricane Center] – Central Pacific
* [http://www.met.gov.fj/index.php?id=152 Fiji Meteorological Service] – South Pacific east of 160°, north of 25° S
* [http://www.imd.gov.in/ India Meteorological Department] – [[Bay of Bengal]] and the [[Arabian Sea]]
* [http://www.jma.go.jp/en/typh/ Japan Meteorological Agency] – NW Pacific
* [http://www.meteo.fr/temps/domtom/La_Reunion/ Météo-France – La Reunion] – South Indian Ocean from Africa to 90° E
* [http://www.nhc.noaa.gov/ US National Hurricane Center] – North Atlantic, Eastern Pacific

;Past storms
* [http://agora.ex.nii.ac.jp/digital-typhoon/ Digital Typhoon: Typhoon Images and Information]
* [http://www.bom.gov.au/bmrc/pubs/tcguide/ch1/ch1_3.htm Global climatology of tropical cyclones]
* [http://www.ncdc.noaa.gov/oa/rsad/gibbs/gibbs.html Global ISCCP B1 Browse System Satellite Archive]- by [[International Satellite Cloud Climatology Project|ISCCP]]
* [http://weather.unisys.com/hurricane/ Unisys historical and contemporary hurricane track data]
* [http://www.hpc.ncep.noaa.gov/tropical/rain/tcrainfall.html United States Tropical Cyclone Rainfall Climatology] – Nearly 30&nbsp;years of tropical cyclone histories with an emphasis on storm total rainfall, in color, up to present. Broken up by year, region, by point of landfall, and North American countries impacted
* [http://www.stormpulse.com Interactive hurricane tracking map] - Includes hurricane data all the way back to the 1850s

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[[Category:Basic meteorological concepts and phenomena]]
[[Category:Tropical cyclone meteorology| ]]
[[Category:Tropical cyclones| ]]
[[Category:Types of cyclone]]
[[Category:Vortices]]
[[Category:Weather hazards]]
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