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125-641: The Cocos (Keeling) Islands ( Cocos Islands Malay : Pulu Kokos [Keeling] ), officially the Territory of Cocos (Keeling) Islands ( / ˈ k oʊ k ə s / ; Cocos Islands Malay: Pulu Kokos [Keeling] ), are an Australian external territory in the Indian Ocean , comprising a small archipelago approximately midway between Australia and Sri Lanka and relatively close to the Indonesian island of Sumatra . The territory's dual name (official since

250-531: A Tropical Cyclone Warning Centre by the World Meteorological Organization 's (WMO) tropical cyclone programme. These warning centers issue advisories which provide basic information and cover a systems present, forecast position, movement and intensity, in their designated areas of responsibility. Meteorological services around the world are generally responsible for issuing warnings for their own country. There are exceptions, as

375-554: A tropical rainforest climate ( Af ) according to the Köppen climate classification ; the archipelago lies approximately midway between the equator and the Tropic of Capricorn . The archipelago has two distinct seasons, the wet season and the dry season. The wettest month is April with precipitation totaling 262.6 millimetres (10.34 in), and the driest month is October with precipitation totaling 88.2 millimetres (3.47 in). Due to

500-416: A 1.5 degree warming lead to "increased proportion of and peak wind speeds of intense tropical cyclones". We can say with medium confidence that regional impacts of further warming include more intense tropical cyclones and/or extratropical storms. Climate change can affect tropical cyclones in a variety of ways: an intensification of rainfall and wind speed, a decrease in overall frequency, an increase in

625-444: A 2019 review paper show a future increase of rainfall rates. Additional sea level rise will increase storm surge levels. It is plausible that extreme wind waves see an increase as a consequence of changes in tropical cyclones, further exacerbating storm surge dangers to coastal communities. The compounding effects from floods, storm surge, and terrestrial flooding (rivers) are projected to increase due to global warming . There

750-582: A base for commerce raiders operating in the Indian Ocean. Following Japan 's entry into the war, Japanese forces occupied neighbouring islands. To avoid drawing their attention to the Cocos cable station and its islands' garrison, the seaplane anchorage between Direction and Horsburgh islands was not used. Radio transmitters were also kept silent, except in emergencies. After the Fall of Singapore in 1942,

875-613: A circle, whirling round their central clear eye , with their surface winds blowing counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere . The opposite direction of circulation is due to the Coriolis effect . Tropical cyclones tend to develop during the summer, but have been noted in nearly every month in most tropical cyclone basins . Tropical cyclones on either side of

1000-642: A communication centre, the Japanese made no attempt either to raid or to occupy them and contented themselves with sending over a reconnaissance aircraft about once a month. On the night of 8–9 May 1942, 15 members of the garrison, from the Ceylon Defence Force , mutinied under the leadership of Gratien Fernando . The mutineers were said to have been provoked by the attitude of their British officers and were also supposedly inspired by Japanese anti-British propaganda. They attempted to take control of

1125-620: A dialect of Malay as their first language. The territory is administered by the Australian federal government's Department of Infrastructure, Transport, Regional Development, Communications and the Arts as an Australian external territory and together with Christmas Island (which is about 960 kilometres (600 mi) to the east) forms the Australian Indian Ocean Territories administrative grouping. However,

1250-405: A flow of warm, moist, rapidly rising air, which starts to rotate cyclonically as it interacts with the rotation of the earth. Several factors are required for these thunderstorms to develop further, including sea surface temperatures of around 27 °C (81 °F) and low vertical wind shear surrounding the system, atmospheric instability, high humidity in the lower to middle levels of

1375-506: A higher intensity. Most tropical cyclones that experience rapid intensification are traversing regions of high ocean heat content rather than lower values. High ocean heat content values can help to offset the oceanic cooling caused by the passage of a tropical cyclone, limiting the effect this cooling has on the storm. Faster-moving systems are able to intensify to higher intensities with lower ocean heat content values. Slower-moving systems require higher values of ocean heat content to achieve

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1500-464: A large number of forecasting centers, uses infrared geostationary satellite imagery and an algorithm based upon the Dvorak technique to assess the intensity of tropical cyclones. The ADT has a number of differences from the conventional Dvorak technique, including changes to intensity constraint rules and the usage of microwave imagery to base a system's intensity upon its internal structure, which prevents

1625-464: A large role in both the classification of a tropical cyclone and the determination of its intensity. Used in warning centers, the method was developed by Vernon Dvorak in the 1970s, and uses both visible and infrared satellite imagery in the assessment of tropical cyclone intensity. The Dvorak technique uses a scale of "T-numbers", scaling in increments of 0.5 from T1.0 to T8.0. Each T-number has an intensity assigned to it, with larger T-numbers indicating

1750-426: A much smaller area. This replenishing of moisture-bearing air after rain may cause multi-hour or multi-day extremely heavy rain up to 40 km (25 mi) from the coastline, far beyond the amount of water that the local atmosphere holds at any one time. This in turn can lead to river flooding , overland flooding, and a general overwhelming of local water control structures across a large area. A tropical cyclone

1875-669: A non-resident Administrator appointed by the Governor-General . They were previously the responsibility of the Department of Transport and Regional Services (before 2007), the Attorney-General's Department (2007–2013), Department of Infrastructure and Regional Development (2013–2017) and Department of Infrastructure, Regional Development and Cities (2017–2020). As of November 2023, the Administrator

2000-493: A number of techniques considered to try to artificially modify tropical cyclones. These techniques have included using nuclear weapons , cooling the ocean with icebergs, blowing the storm away from land with giant fans, and seeding selected storms with dry ice or silver iodide . These techniques, however, fail to appreciate the duration, intensity, power or size of tropical cyclones. A variety of methods or techniques, including surface, satellite, and aerial, are used to assess

2125-721: A partial alternative to the Paya Lebar Air Base . Descendants of the Cocos Malays brought to the islands from the Malay Peninsula , the Indonesian archipelago , Southern Africa and New Guinea by Hare and by Clunies-Ross as indentured workers , slaves or convicts are as of 2019 seeking recognition from the Australian government to be acknowledged as Indigenous Australians . The capital of

2250-422: A process known as rapid intensification, a period in which the maximum sustained winds of a tropical cyclone increase by 30  kn (56 km/h; 35 mph) or more within 24 hours. Similarly, rapid deepening in tropical cyclones is defined as a minimum sea surface pressure decrease of 1.75 hPa (0.052 inHg) per hour or 42 hPa (1.2 inHg) within a 24-hour period; explosive deepening occurs when

2375-429: A remnant low-pressure area . Remnant systems may persist for several days before losing their identity. This dissipation mechanism is most common in the eastern North Pacific. Weakening or dissipation can also occur if a storm experiences vertical wind shear which causes the convection and heat engine to move away from the center. This normally ceases the development of a tropical cyclone. In addition, its interaction with

2500-465: A round. At low tide one could walk over, at high tide one could take a boat, in order to take out or to kill, say, a shark, who had come into the pond and was disturbing the turtles and fish inside. Because there used to be all sorts of fishes in there. There were in fact two gates: boats could come in." This Austronesian languages -related article is a stub . You can help Misplaced Pages by expanding it . Tropical cyclone A tropical cyclone

2625-504: A second language in schools, and Malaysian has prestige status; both are influencing the language, bringing it more in line with standard Malay. There is also a growing influence of English , considering the Islands having been an Australian territory and globalization drifting modern terms into the daily parlance. In 2009, Cocos Malay students were prohibited from using their own language and failure to comply resulted in punishment in

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2750-572: A small book about his time with wife and son from 1964 to 1966 working at the Cable Station on Direction Island. In the 1970s, the Australian government's dissatisfaction with the Clunies-Ross feudal style of rule of the island increased. In 1978, Australia forced the family to sell the islands for the sum of A$ 6,250,000, using the threat of compulsory acquisition. By agreement, the family retained ownership of Oceania House, their home on

2875-569: A storm. Tropical cyclone scales , such as the Saffir-Simpson hurricane wind scale and Australia's scale (Bureau of Meteorology), only use wind speed for determining the category of a storm. The most intense storm on record is Typhoon Tip in the northwestern Pacific Ocean in 1979, which reached a minimum pressure of 870  hPa (26  inHg ) and maximum sustained wind speeds of 165 kn (85 m/s; 305 km/h; 190 mph). The highest maximum sustained wind speed ever recorded

3000-581: A stronger system. Tropical cyclones are assessed by forecasters according to an array of patterns, including curved banding features , shear, central dense overcast, and eye, to determine the T-number and thus assess the intensity of the storm. The Cooperative Institute for Meteorological Satellite Studies works to develop and improve automated satellite methods, such as the Advanced Dvorak Technique (ADT) and SATCON. The ADT, used by

3125-405: A system has dissipated or lost its tropical characteristics, its remnants could regenerate a tropical cyclone if environmental conditions become favorable. A tropical cyclone can dissipate when it moves over waters significantly cooler than 26.5 °C (79.7 °F). This will deprive the storm of such tropical characteristics as a warm core with thunderstorms near the center, so that it becomes

3250-498: A total land area of 13.1 square kilometres (5.1 sq mi). Only Home Island and West Island are populated. The Cocos Malays maintain weekend shacks, referred to as pondoks, on most of the larger islands. There are no rivers or lakes on either atoll. Fresh water resources are limited to water lenses on the larger islands, underground accumulations of rainwater lying above the seawater. These lenses are accessed through shallow bores or wells. Cocos (Keeling) Islands experience

3375-624: A town in Borneo , and found that "he could not confine himself to the tame life that civilisation affords". Clunies-Ross returned two years later with his wife, children and mother-in-law, and found Hare already established on the island and living with the private harem. A feud grew between the two. Clunies-Ross's eight sailors "began at once the invasion of the new kingdom to take possession of it, women and all". After some time, Hare's women began deserting him, and instead finding themselves partners amongst Clunies-Ross's sailors. Disheartened, Hare left

3500-529: A tropical cyclone are a result of the conservation of angular momentum imparted by the Earth's rotation as air flows inwards toward the axis of rotation. As a result, cyclones rarely form within 5° of the equator . Tropical cyclones are very rare in the South Atlantic (although occasional examples do occur ) due to consistently strong wind shear and a weak Intertropical Convergence Zone . In contrast,

3625-461: A tropical cyclone's core has a negative effect on its development and intensity by diminishing atmospheric convection and introducing asymmetries in the storm's structure. Symmetric, strong outflow leads to a faster rate of intensification than observed in other systems by mitigating local wind shear. Weakening outflow is associated with the weakening of rainbands within a tropical cyclone. Tropical cyclones may still intensify, even rapidly, in

3750-401: A tropical cyclone's intensity or the direction it is traveling. Wind-pressure relationships (WPRs) are used as a way to determine the pressure of a storm based on its wind speed. Several different methods and equations have been proposed to calculate WPRs. Tropical cyclones agencies each use their own, fixed WPR, which can result in inaccuracies between agencies that are issuing estimates on

3875-831: A typhoon. This happened in 2014 for Hurricane Genevieve , which became Typhoon Genevieve. Within the Southern Hemisphere, it is either called a hurricane, tropical cyclone or a severe tropical cyclone, depending on if it is located within the South Atlantic, South-West Indian Ocean, Australian region or the South Pacific Ocean. The descriptors for tropical cyclones with wind speeds below 65 kn (120 km/h; 75 mph) vary by tropical cyclone basin and may be further subdivided into categories such as "tropical storm", "cyclonic storm", "tropical depression", or "deep depression". The practice of using given names to identify tropical cyclones dates back to

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4000-724: Is Farzian Zainal , she is also the Administrator of Christmas Island . These two territories comprise the Australian Indian Ocean Territories . The Australian Government provides Commonwealth-level government services through the Christmas Island Administration and the Department of Infrastructure, Transport, Regional Development, Communications and the Arts. As per the Federal Government's Territories Law Reform Act 1992 , which came into force on 1 July 1992, Western Australian laws are applied to

4125-779: Is a women's rights organisation that represents the view of women at a local and national level. The archipelago was discovered in 1609 by Captain William Keeling of the East India Company , on a return voyage from the East Indies. North Keeling was sketched by Ekeberg, a Swedish captain, in 1749, showing the presence of coconut palms . It also appears on a 1789 chart produced by British hydrographer Alexander Dalrymple . In 1825, Scottish merchant seaman Captain John Clunies-Ross stopped briefly at

4250-473: Is a rapidly rotating storm system with a low-pressure center, a closed low-level atmospheric circulation , strong winds, and a spiral arrangement of thunderstorms that produce heavy rain and squalls . Depending on its location and strength, a tropical cyclone is called a hurricane ( / ˈ h ʌr ɪ k ən , - k eɪ n / ), typhoon ( / t aɪ ˈ f uː n / ), tropical storm , cyclonic storm , tropical depression , or simply cyclone . A hurricane

4375-636: Is a strong tropical cyclone that occurs in the Atlantic Ocean or northeastern Pacific Ocean . A typhoon occurs in the northwestern Pacific Ocean. In the Indian Ocean and South Pacific, comparable storms are referred to as "tropical cyclones". In modern times, on average around 80 to 90 named tropical cyclones form each year around the world, over half of which develop hurricane-force winds of 65  kn (120 km/h; 75 mph) or more. Tropical cyclones typically form over large bodies of relatively warm water. They derive their energy through

4500-415: Is assumed at this stage that a tropical cyclone has become self-sustaining and can continue to intensify without any help from its environment. Depending on its location and strength, a tropical cyclone is referred to by different names , including hurricane , typhoon , tropical storm , cyclonic storm , tropical depression , or simply cyclone . A hurricane is a strong tropical cyclone that occurs in

4625-406: Is calculated as: where p {\textstyle p} is the density of air, u {\textstyle u} is a sustained surface wind speed value, and d v {\textstyle d_{v}} is the volume element . Around the world, tropical cyclones are classified in different ways, based on the location ( tropical cyclone basins ), the structure of

4750-554: Is currently no consensus on how climate change will affect the overall frequency of tropical cyclones. A majority of climate models show a decreased frequency in future projections. For instance, a 2020 paper comparing nine high-resolution climate models found robust decreases in frequency in the Southern Indian Ocean and the Southern Hemisphere more generally, while finding mixed signals for Northern Hemisphere tropical cyclones. Observations have shown little change in

4875-414: Is cut off from its supply of warm moist maritime air and starts to draw in dry continental air. This, combined with the increased friction over land areas, leads to the weakening and dissipation of the tropical cyclone. Over a mountainous terrain, a system can quickly weaken. Over flat areas, it may endure for two to three days before circulation breaks down and dissipates. Over the years, there have been

5000-445: Is pleasant, moderated by the southeast trade winds for about nine months of the year and with moderate rainfall. Tropical cyclones may occur in the early months of the year. North Keeling Island is an atoll consisting of just one C-shaped island, a nearly closed atoll ring with a small opening into the lagoon, about 50 metres (160 ft) wide, on the east side. The island measures 1.1 square kilometres (270 acres) in land area and

5125-445: Is the generic term for a warm-cored, non-frontal synoptic-scale low-pressure system over tropical or subtropical waters around the world. The systems generally have a well-defined center which is surrounded by deep atmospheric convection and a closed wind circulation at the surface. A tropical cyclone is generally deemed to have formed once mean surface winds in excess of 35 kn (65 km/h; 40 mph) are observed. It

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5250-512: Is the greatest. However, each particular basin has its own seasonal patterns. On a worldwide scale, May is the least active month, while September is the most active month. November is the only month in which all the tropical cyclone basins are in season. In the Northern Atlantic Ocean , a distinct cyclone season occurs from June 1 to November 30, sharply peaking from late August through September. The statistical peak of

5375-405: Is the storm's wind speed and r {\textstyle r} is the radius of hurricane-force winds. The Hurricane Severity Index is a scale that can assign up to 50 points to a system; up to 25 points come from intensity, while the other 25 come from the size of the storm's wind field. The IKE model measures the destructive capability of a tropical cyclone via winds, waves, and surge. It

5500-521: Is uninhabited. The lagoon is about 0.5 square kilometres (120 acres). North Keeling Island and the surrounding sea to 1.5 km (0.93 mi) from shore form the Pulu Keeling National Park , established on 12 December 1995. It is home to the only surviving population of the endemic, and endangered, Cocos Buff-banded Rail . South Keeling Islands is an atoll consisting of 24 individual islets forming an incomplete atoll ring, with

5625-620: The African easterly jet and areas of atmospheric instability give rise to cyclones in the Atlantic Ocean and Caribbean Sea . Heat energy from the ocean acts as the accelerator for tropical cyclones. This causes inland regions to suffer far less damage from cyclones than coastal regions, although the impacts of flooding are felt across the board. Coastal damage may be caused by strong winds and rain, high waves (due to winds), storm surges (due to wind and severe pressure changes), and

5750-452: The Atlantic Ocean or northeastern Pacific Ocean , and a typhoon occurs in the northwestern Pacific Ocean. In the Indian Ocean and South Pacific, comparable storms are referred to as "tropical cyclones", and such storms in the Indian Ocean can also be called "severe cyclonic storms". Tropical refers to the geographical origin of these systems, which form almost exclusively over tropical seas. Cyclone refers to their winds moving in

5875-647: The Hurricane Surge Index , the Hurricane Severity Index , the Power Dissipation Index (PDI), and integrated kinetic energy (IKE). ACE is a metric of the total energy a system has exerted over its lifespan. ACE is calculated by summing the squares of a cyclone's sustained wind speed, every six hours as long as the system is at or above tropical storm intensity and either tropical or subtropical. The calculation of

6000-565: The Keeling–Cocos Islands (19th century). Cocos refers to the abundant coconut trees, while Keeling refers to William Keeling , who discovered the islands in 1609. John Clunies-Ross, who sailed there in the Borneo in 1825, called the group the Borneo Coral Isles , restricting Keeling to North Keeling , and calling South Keeling "the Cocos properly so called". The form Cocos (Keeling) Islands , attested from 1916,

6125-559: The Madden–Julian oscillation . The IPCC Sixth Assessment Report summarize the latest scientific findings about the impact of climate change on tropical cyclones. According to the report, we have now better understanding about the impact of climate change on tropical storm than before. Major tropical storms likely became more frequent in the last 40 years. We can say with high confidence that climate change increase rainfall during tropical cyclones. We can say with high confidence that

6250-748: The Northern Territory ) and in the Senate by Northern Territory senators. At the 2022 Australian federal election the Labor Party received absolute majorities from Cocos electors in both the House of Representatives and the Senate. Cocos Islands Malay language Cocos Malay derives from the Malay trade languages of the 19th century, specifically the Betawi language . Malay is offered as

6375-533: The Royal Air Force ), which were also stationed on the islands. When in July 1945 No. 99 and No. 356 RAF squadrons arrived on West Island, they brought with them a daily newspaper called Atoll which contained news of what was happening in the outside world. Run by airmen in their off-duty hours, it achieved fame when dropped by Liberator bombers on POW camps over the heads of the Japanese guards. In 1946,

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6500-460: The Saffir–Simpson scale . Climate oscillations such as El Niño–Southern Oscillation (ENSO) and the Madden–Julian oscillation modulate the timing and frequency of tropical cyclone development. Rossby waves can aid in the formation of a new tropical cyclone by disseminating the energy of an existing, mature storm. Kelvin waves can contribute to tropical cyclone formation by regulating

6625-575: The Saffir–Simpson scale . The trend was most clear in the North Atlantic and in the Southern Indian Ocean. In the North Pacific, tropical cyclones have been moving poleward into colder waters and there was no increase in intensity over this period. With 2 °C (3.6 °F) warming, a greater percentage (+13%) of tropical cyclones are expected to reach Category 4 and 5 strength. A 2019 study indicates that climate change has been driving

6750-415: The gun battery on the islands. The Cocos Islands Mutiny was crushed, but the mutineers murdered one non-mutinous soldier and wounded one officer. Seven of the mutineers were sentenced to death at a trial that was later alleged to have been improperly conducted, though the guilt of the accused was admitted. Four of the sentences were commuted, but three men were executed, including Fernando. These were to be

6875-514: The troposphere , enough Coriolis force to develop a low-pressure center , and a pre-existing low-level focus or disturbance. There is a limit on tropical cyclone intensity which is strongly related to the water temperatures along its path. and upper-level divergence. An average of 86 tropical cyclones of tropical storm intensity form annually worldwide. Of those, 47 reach strength higher than 119 km/h (74 mph), and 20 become intense tropical cyclones, of at least Category 3 intensity on

7000-640: The Atlantic hurricane season is September 10. The Northeast Pacific Ocean has a broader period of activity, but in a similar time frame to the Atlantic. The Northwest Pacific sees tropical cyclones year-round, with a minimum in February and March and a peak in early September. In the North Indian basin, storms are most common from April to December, with peaks in May and November. In the Southern Hemisphere,

7125-606: The Australian cruiser, which caught up to the troop convoy in Colombo on 15 November, then transported to Malta and handed over the prisoners to the British Army . An additional 50 German personnel from the shore party, unable to be recovered before Sydney arrived, commandeered a schooner and escaped from Direction Island, eventually arriving in Constantinople . Emden was the last active Central Powers warship in

7250-508: The Australian parliament approved plans to extend the airstrip by 150 metres so that it could take Boeing P-8 Poseidon aircraft capable of low-level anti-submarine warfare operations and high-tech military surveillance. Construction was scheduled to start in 2024 and be completed by 2026. Prior to the upgrade, the United States had been using the airstrip for several decades as a stopover point between Diego Garcia and Guam , and as

7375-604: The British Settlements Acts, 1887 and 1945, as applied by the Act of 1946. The legal steps for effecting the transfer were as follows: The reason for this comparatively complex machinery was due to the terms of the Straits Settlement (Repeal) Act, 1946. According to Sir Kenneth Roberts-Wray "any other procedure would have been of doubtful validity". The separation involved three steps: separation from

7500-584: The Clunies-Ross family still live on the Cocos. Extensive preparations were undertaken by the government of Australia to prepare the Cocos Malays to vote in their referendum of self-determination. Discussions began in 1982, with an aim of holding the referendum, under United Nations supervision, in mid-1983. Under guidelines developed by the UN Decolonization Committee, residents were to be offered three choices: full independence, free association, or integration with Australia. The last option

7625-523: The Clunies-Ross family: 229 voted for integration, 21 for Free Association, nine for independence, and two failed to indicate a preference. In the first decade of the 21st century, a series of disputes have occurred between the Muslim and the non-Muslim population of the islands. The airstrip on West Island has an airstrip that is more than two kilometres long and is designed to accommodate Boeing 737 passenger flights and smaller military planes. In 2023,

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7750-535: The Cocos Islands, "so far as they are capable of applying in the Territory"; non-application or partial application of such laws is at the discretion of the federal government. The Act also gives Western Australian courts judicial power over the islands. The Cocos Islands remain constitutionally distinct from Western Australia, however; the power of the state to legislate for the territory is power-delegated by

7875-533: The Colony of Singapore; transfer by United Kingdom and acceptance by Australia. H. J. Hull was appointed the first official representative (now administrator) of the new territory. He had been a lieutenant-commander in the Royal Australian Navy and was released for the purpose. Under Commonwealth Cabinet Decision 1573 of 9 September 1958, Hull's appointment was terminated and John William Stokes

8000-556: The Equator generally have their origins in the Intertropical Convergence Zone , where winds blow from either the northeast or southeast. Within this broad area of low-pressure, air is heated over the warm tropical ocean and rises in discrete parcels, which causes thundery showers to form. These showers dissipate quite quickly; however, they can group together into large clusters of thunderstorms. This creates

8125-586: The Governor of Ceylon was made Governor of the islands, and, by further Letters Patent in 1886, responsibility for the islands was transferred to the Governor of the Straits Settlement to exercise his functions as "Governor of Cocos Islands". The islands were made part of the Straits Settlement under an Order in Council of 20 May 1903. Meanwhile, in 1886 Queen Victoria had, by indenture, granted

8250-506: The Indian or Pacific Ocean, which meant troopships from Australia and New Zealand could sail without naval escort, and Allied ships could be deployed elsewhere. During World War II , the cable station was once again a vital link. The Cocos were valuable for direction finding by the Y service , the worldwide intelligence system used during the war. Allied planners noted that the islands might be seized as an airfield for German planes and as

8375-632: The PDI is similar in nature to ACE, with the major difference being that wind speeds are cubed rather than squared. The Hurricane Surge Index is a metric of the potential damage a storm may inflict via storm surge. It is calculated by squaring the dividend of the storm's wind speed and a climatological value (33 m/s or 74 mph), and then multiplying that quantity by the dividend of the radius of hurricane-force winds and its climatological value (96.6 km or 60.0 mi). This can be represented in equation form as: where v {\textstyle v}

8500-463: The South Atlantic is not a major basin, and not an official basin according to the WMO. Each year on average, around 80 to 90 named tropical cyclones form around the world, of which over half develop hurricane-force winds of 65 kn (120 km/h; 75 mph) or more. Worldwide, tropical cyclone activity peaks in late summer, when the difference between temperatures aloft and sea surface temperatures

8625-453: The Territory of Cocos (Keeling) Islands is West Island while the largest settlement is the village of Bantam, on Home Island. Governance of the islands is based on the Cocos (Keeling) Islands Act 1955 and depends heavily on the laws of Australia. The islands are administered from Canberra by the Department of Infrastructure, Transport, Regional Development, Communications and the Arts through

8750-610: The United States National Hurricane Center and Fiji Meteorological Service issue alerts, watches and warnings for various island nations in their areas of responsibility. The United States Joint Typhoon Warning Center and Fleet Weather Center also publicly issue warnings about tropical cyclones on behalf of the United States Government . The Brazilian Navy Hydrographic Center names South Atlantic tropical cyclones , however

8875-591: The Western Pacific. Tropical cyclones have to have a significant amount of gale-force winds occurring around the center before they are named within the Southern Hemisphere . The names of significant tropical cyclones in the North Atlantic Ocean, Pacific Ocean, and Australian region are retired from the naming lists and replaced with another name. Tropical cyclones that develop around the world are assigned an identification code consisting of

9000-598: The administration of the islands reverted to Singapore and it became part of the Colony of Singapore. On 23 November 1955, the islands were transferred from the United Kingdom to the Commonwealth of Australia . Immediately before the transfer the islands were part of the United Kingdom's Colony of Singapore, in accordance with the Straits Settlements (Repeal) Act, 1946 of the United Kingdom and

9125-435: The development of the westerlies . Cyclone formation is usually reduced 3 days prior to the wave's crest and increased during the 3 days after. The majority of tropical cyclones each year form in one of seven tropical cyclone basins, which are monitored by a variety of meteorological services and warning centers. Ten of these warning centers worldwide are designated as either a Regional Specialized Meteorological Centre or

9250-424: The early 19th century. One of the first settlers was John Clunies-Ross, a Scottish merchant; much of the island's current population is descended from the Malay workers he brought in to work his copra plantation. The Clunies-Ross family ruled the islands as a private fiefdom for almost 150 years, with the head of the family usually recognised as resident magistrate . The British annexed the islands in 1857, and for

9375-492: The equator, then move poleward past the ridge axis before recurving into the main belt of the Westerlies . When the subtropical ridge position shifts due to El Niño, so will the preferred tropical cyclone tracks. Areas west of Japan and Korea tend to experience much fewer September–November tropical cyclone impacts during El Niño and neutral years. During La Niña years, the formation of tropical cyclones, along with

9500-469: The evaporation of water from the ocean surface, which ultimately condenses into clouds and rain when moist air rises and cools to saturation . This energy source differs from that of mid-latitude cyclonic storms , such as nor'easters and European windstorms , which are powered primarily by horizontal temperature contrasts . Tropical cyclones are typically between 100 and 2,000 km (62 and 1,243 mi) in diameter. The strong rotating winds of

9625-481: The eyewall of the storm, and an upper-level anticyclone helps channel this air away from the cyclone efficiently. However, some cyclones such as Hurricane Epsilon have rapidly intensified despite relatively unfavorable conditions. There are a number of ways a tropical cyclone can weaken, dissipate, or lose its tropical characteristics. These include making landfall, moving over cooler water, encountering dry air, or interacting with other weather systems; however, once

9750-564: The federal government. The kind of services typically provided by a state government elsewhere in Australia are provided by departments of the Western Australian Government, and by contractors, with the costs met by the federal government. There also exists a unicameral Cocos (Keeling) Islands Shire Council with seven seats. A full term lasts four years, though elections are held every two years; approximately half

9875-640: The form of "speaking tickets" which meant that they were required to carry out cleaning duties in school. However, this form of language restriction ended by 2011. It has the following characteristics: There are three ways in which Cocos Malay differs from Standard Malay and Indonesian : Saban minggu orang tu kərja'an presa tu, raun tu. Kalo' aer kring bole mənyəbərang, aer bəsar bole bawa' jukung tu, ame' məngkali ada yu masu', ganggu nang di dalam situ tu, bunu tu. Itu macam-macam ikan ada situ tu. Emang dia punya pintu dua, jukung bole masu' emangnya. "Every week people would go and check them, they would go on

10000-410: The form of cold water from falling raindrops (this is because the atmosphere is cooler at higher altitudes). Cloud cover may also play a role in cooling the ocean, by shielding the ocean surface from direct sunlight before and slightly after the storm passage. All these effects can combine to produce a dramatic drop in sea surface temperature over a large area in just a few days. Conversely, the mixing of

10125-453: The frequency of very intense storms and a poleward extension of where the cyclones reach maximum intensity are among the possible consequences of human-induced climate change. Tropical cyclones use warm, moist air as their fuel. As climate change is warming ocean temperatures , there is potentially more of this fuel available. Between 1979 and 2017, there was a global increase in the proportion of tropical cyclones of Category 3 and higher on

10250-532: The general public regarding forecasts, watches, and warnings. Since the systems can last a week or longer, and more than one can be occurring in the same basin at the same time, the names are thought to reduce the confusion about what storm is being described. Names are assigned in order from predetermined lists with one, three, or ten-minute sustained wind speeds of more than 65 km/h (40 mph) depending on which basin it originates. Standards vary from basin to basin. Some tropical depressions are named in

10375-451: The intensity from leveling off before an eye emerges in infrared imagery. The SATCON weights estimates from various satellite-based systems and microwave sounders , accounting for the strengths and flaws in each individual estimate, to produce a consensus estimate of a tropical cyclone's intensity which can be more reliable than the Dvorak technique at times. Multiple intensity metrics are used, including accumulated cyclone energy (ACE),

10500-522: The intensity of a tropical cyclone. Reconnaissance aircraft fly around and through tropical cyclones, outfitted with specialized instruments, to collect information that can be used to ascertain the winds and pressure of a system. Tropical cyclones possess winds of different speeds at different heights. Winds recorded at flight level can be converted to find the wind speeds at the surface. Surface observations, such as ship reports, land stations, mesonets , coastal stations, and buoys, can provide information on

10625-558: The island. He died in Bencoolen in 1834. Encouraged by members of the former harem, Clunies-Ross then recruited Malays to come to the island for work and wives. Clunies-Ross's workers were paid in a currency called the Cocos rupee, a currency John Clunies-Ross minted himself that could only be redeemed at the company store. On 1 April 1836, HMS  Beagle under Captain Robert FitzRoy arrived to take soundings to establish

10750-545: The island. In 1983, the Australian government reneged on this agreement and told John Clunies-Ross that he should leave the Cocos. The following year the High Court of Australia ruled that resumption of Oceania House was unlawful, but the Australian government ordered that no government business was to be granted to Clunies-Ross's shipping company, an action that contributed to his bankruptcy. John Clunies-Ross later moved to Perth, Western Australia . However, some members of

10875-524: The islanders do have a degree of self-government through the local shire council . Many public services – including health, education, and policing – are provided by the state of Western Australia , and Western Australian law applies except where the federal government has determined otherwise. The territory also uses Western Australian postcodes. The islands were discovered in 1609 by the British sea captain William Keeling , but no settlement occurred until

11000-463: The islands in perpetuity to John Clunies-Ross. The head of the family enjoyed semi-official status as Resident Magistrate and Government representative. In 1901 a telegraph cable station was established on Direction Island. Undersea cables went to Rodrigues , Mauritius , Batavia , Java and Fremantle , Western Australia . In 1910 a wireless station was established to communicate with passing ships. The cable station ceased operation in 1966. On

11125-467: The islands on a trip to India, nailing up a Union Jack and planning to return and settle on the islands with his family in the future. Wealthy Englishman Alexander Hare had similar plans, and hired a captain – coincidentally, Clunies-Ross's brother – to bring him and a volunteer harem of 40 Malay women to the islands, where he hoped to establish his private residence. Hare had previously served as resident of Banjarmasin ,

11250-468: The islands were administered from Ceylon and West and Direction Islands were placed under Allied military administration. The islands' garrison initially consisted of a platoon from the British Army's King's African Rifles , located on Horsburgh Island, with two 6-inch (152.4 mm) guns to cover the anchorage. The local inhabitants all lived on Home Island. Despite the importance of the islands as

11375-543: The islands' incorporation into Australia in 1955) reflects that the islands have historically been known as either the Cocos Islands or the Keeling Islands . The territory consists of two atolls made up of 27 coral islands , of which only two – West Island and Home Island – are inhabited. The population of around 600 people consists mainly of Cocos Malays , who mostly practise Sunni Islam and speak

11500-693: The late 1800s and early 1900s and gradually superseded the existing system—simply naming cyclones based on what they hit. The system currently used provides positive identification of severe weather systems in a brief form, that is readily understood and recognized by the public. The credit for the first usage of personal names for weather systems is generally given to the Queensland Government Meteorologist Clement Wragge who named systems between 1887 and 1907. This system of naming weather systems fell into disuse for several years after Wragge retired, until it

11625-404: The main belt of the Westerlies , by means of merging with a nearby frontal zone, can cause tropical cyclones to evolve into extratropical cyclones . This transition can take 1–3 days. Should a tropical cyclone make landfall or pass over an island, its circulation could start to break down, especially if it encounters mountainous terrain. When a system makes landfall on a large landmass, it

11750-476: The members retire each two years. As of March 2024 the president of the shire is Aindil Minkom. The most recent local election took place on 21 October 2023 alongside elections on Christmas Island . Cocos (Keeling) Islands residents who are Australian citizens also vote in federal elections . Cocos (Keeling) Islanders are represented in the House of Representatives by the member for the Division of Lingiari (in

11875-543: The morning of 9 November 1914, the islands became the site of the Battle of Cocos , one of the first naval battles of World War I . A landing party from the German cruiser SMS  Emden captured and disabled the wireless and cable communications station on Direction Island , but not before the station was able to transmit a distress call. An Allied troop convoy was passing nearby, and the Australian cruiser HMAS  Sydney

12000-466: The next century they were administered from either Ceylon or Singapore . The territory was transferred to Australia in 1955, although until 1979 virtually all of the territory's real estate still belonged to the Clunies-Ross family. The islands have been called the Cocos Islands (from 1622), the Keeling Islands (from 1703), the Cocos–Keeling Islands (since James Horsburgh in 1805) and

12125-522: The observed trend of rapid intensification of tropical cyclones in the Atlantic basin. Rapidly intensifying cyclones are hard to forecast and therefore pose additional risk to coastal communities. Warmer air can hold more water vapor: the theoretical maximum water vapor content is given by the Clausius–Clapeyron relation , which yields ≈7% increase in water vapor in the atmosphere per 1 °C (1.8 °F) warming. All models that were assessed in

12250-796: The only British Commonwealth soldiers executed for mutiny during the Second World War. On 25 December 1942, the Japanese submarine I-166 bombarded the islands but caused no damage. Later in the war, two airstrips were built, and three bomber squadrons were moved to the islands to conduct raids against Japanese targets in South East Asia and to provide support during the planned reinvasion of Malaya and reconquest of Singapore. The first aircraft to arrive were Supermarine Spitfire Mk VIIIs of No. 136 Squadron RAF . They included some Liberator bombers from No. 321 (Netherlands) Squadron RAF (members of exiled Dutch forces serving with

12375-466: The overall frequency of tropical cyclones worldwide, with increased frequency in the North Atlantic and central Pacific, and significant decreases in the southern Indian Ocean and western North Pacific. There has been a poleward expansion of the latitude at which the maximum intensity of tropical cyclones occurs, which may be associated with climate change. In the North Pacific, there may also have been an eastward expansion. Between 1949 and 2016, there

12500-642: The population is 40 years, slightly older than the median Australian population age of 38 years. As of 2021, there are no people living on the Cocos Islands who identify as Indigenous Australians (Aboriginal or Torres Strait Islander). Religion in Cocos Islands (2021) The majority religion of the Cocos Islands is Islam, with 65.6% of the total population identifying as Muslim, followed by Unspecified (15.3%), Non-religious (14.0%), Catholic (2.0%), Anglican (1.5%). The remaining 1.6% of Cocos Islanders identify as secular or hold various other beliefs (including atheism, agnosticism and unspecified spiritual beliefs). 73.5% of

12625-485: The population were born in Australia - either on the mainland, on the Cocos Islands, or in another Australian territory. The remaining 26.5% come from other countries, including Malaysia (4.0%), England (1.3%), New Zealand (1.2%), Singapore (0.5%) and Argentina (0.5%), among others. 61.2% of the population speak Malay at home, while 19.1% speak English, and 3.5% speak another language (including Spanish and various Austronesian and African languages). Kaum Ibu (Women's Group)

12750-440: The potential of spawning tornadoes . Climate change affects tropical cyclones in several ways. Scientists found that climate change can exacerbate the impact of tropical cyclones by increasing their duration, occurrence, and intensity due to the warming of ocean waters and intensification of the water cycle . Tropical cyclones draw in air from a large area and concentrate the water content of that air into precipitation over

12875-413: The presence of moderate or strong wind shear depending on the evolution and structure of the storm's convection. The size of tropical cyclones plays a role in how quickly they intensify. Smaller tropical cyclones are more prone to rapid intensification than larger ones. The Fujiwhara effect , which involves interaction between two tropical cyclones, can weaken and ultimately result in the dissipation of

13000-467: The profile of the atoll as part of the survey expedition of the Beagle . To the naturalist Charles Darwin , aboard the ship, the results supported a theory he had developed of how atolls formed, which he later published as The Structure and Distribution of Coral Reefs . He studied the natural history of the islands and collected specimens. Darwin's assistant Syms Covington noted that "an Englishman [he

13125-444: The release of latent heat from the saturated soil. Orographic lift can cause a significant increase in the intensity of the convection of a tropical cyclone when its eye moves over a mountain, breaking the capped boundary layer that had been restraining it. Jet streams can both enhance and inhibit tropical cyclone intensity by influencing the storm's outflow as well as vertical wind shear. On occasion, tropical cyclones may undergo

13250-492: The same intensity. The passage of a tropical cyclone over the ocean causes the upper layers of the ocean to cool substantially, a process known as upwelling , which can negatively influence subsequent cyclone development. This cooling is primarily caused by wind-driven mixing of cold water from deeper in the ocean with the warm surface waters. This effect results in a negative feedback process that can inhibit further development or lead to weakening. Additional cooling may come in

13375-492: The same system. The ASCAT is a scatterometer used by the MetOp satellites to map the wind field vectors of tropical cyclones. The SMAP uses an L-band radiometer channel to determine the wind speeds of tropical cyclones at the ocean surface, and has been shown to be reliable at higher intensities and under heavy rainfall conditions, unlike scatterometer-based and other radiometer-based instruments. The Dvorak technique plays

13500-513: The sea can result in heat being inserted in deeper waters, with potential effects on global climate . Vertical wind shear decreases tropical cyclone predicability, with storms exhibiting wide range of responses in the presence of shear. Wind shear often negatively affects tropical cyclone intensification by displacing moisture and heat from a system's center. Low levels of vertical wind shear are most optimal for strengthening, while stronger wind shear induces weakening. Dry air entraining into

13625-545: The strong maritime control, temperatures vary little although its location is some distance from the Equator . The hottest month is March with an average high temperature of 30.0 °C (86.0 °F), while the coolest month is September with an average low temperature of 24.2 °C (75.6 °F). According to the 2021 Australian Census, the population of the Cocos Islands is 593 people. The gender distribution stands at an approximate 51% male and 49% female. The median age of

13750-617: The subtropical ridge position, shifts westward across the western Pacific Ocean, which increases the landfall threat to China and much greater intensity in the Philippines . The Atlantic Ocean experiences depressed activity due to increased vertical wind shear across the region during El Niño years. Tropical cyclones are further influenced by the Atlantic Meridional Mode , the Quasi-biennial oscillation and

13875-419: The surface pressure decreases by 2.5 hPa (0.074 inHg) per hour for at least 12 hours or 5 hPa (0.15 inHg) per hour for at least 6 hours. For rapid intensification to occur, several conditions must be in place. Water temperatures must be extremely high, near or above 30 °C (86 °F), and water of this temperature must be sufficiently deep such that waves do not upwell cooler waters to

14000-483: The surface. On the other hand, Tropical Cyclone Heat Potential is one of such non-conventional subsurface oceanographic parameters influencing the cyclone intensity. Wind shear must be low. When wind shear is high, the convection and circulation in the cyclone will be disrupted. Usually, an anticyclone in the upper layers of the troposphere above the storm must be present as well—for extremely low surface pressures to develop, air must be rising very rapidly in

14125-648: The system and its intensity. For example, within the Northern Atlantic and Eastern Pacific basins, a tropical cyclone with wind speeds of over 65  kn (120 km/h; 75 mph) is called a hurricane , while it is called a typhoon or a severe cyclonic storm within the Western Pacific or North Indian oceans. When a hurricane passes west across the International Dateline in the Northern Hemisphere, it becomes known as

14250-423: The tropical cyclone year begins on July 1 and runs all year-round encompassing the tropical cyclone seasons, which run from November 1 until the end of April, with peaks in mid-February to early March. Of various modes of variability in the climate system, El Niño–Southern Oscillation has the largest effect on tropical cyclone activity. Most tropical cyclones form on the side of the subtropical ridge closer to

14375-451: The weaker of two tropical cyclones by reducing the organization of the system's convection and imparting horizontal wind shear. Tropical cyclones typically weaken while situated over a landmass because conditions are often unfavorable as a result of the lack of oceanic forcing. The Brown ocean effect can allow a tropical cyclone to maintain or increase its intensity following landfall , in cases where there has been copious rainfall, through

14500-402: The wind speed of Hurricane Helene by 11%, it increased the destruction from it by more than twice. According to World Weather Attribution the influence of climate change on the rainfall of some latest hurricanes can be described as follows: Tropical cyclone intensity is based on wind speeds and pressure. Relationships between winds and pressure are often used in determining the intensity of

14625-795: Was 185 kn (95 m/s; 345 km/h; 215 mph) in Hurricane Patricia in 2015—the most intense cyclone ever recorded in the Western Hemisphere . Warm sea surface temperatures are required for tropical cyclones to form and strengthen. The commonly-accepted minimum temperature range for this to occur is 26–27 °C (79–81 °F), however, multiple studies have proposed a lower minimum of 25.5 °C (77.9 °F). Higher sea surface temperatures result in faster intensification rates and sometimes even rapid intensification . High ocean heat content , also known as Tropical Cyclone Heat Potential , allows storms to achieve

14750-527: Was a slowdown in tropical cyclone translation speeds. It is unclear still to what extent this can be attributed to climate change: climate models do not all show this feature. A 2021 study review article concluded that the geographic range of tropical cyclones will probably expand poleward in response to climate warming of the Hadley circulation . When hurricane winds speed rise by 5%, its destructive power rise by about 50%. Therfore, as climate change increased

14875-675: Was appointed on secondment from the Northern Territory police. A media release at the end of October 1958 by the Minister for Territories, Hasluck, commended Hull's three years of service on Cocos. Stokes served in the position from 31 October 1958 to 30 September 1960. His son's boyhood memories and photos of the Islands have been published. C. I. Buffett MBE from Norfolk Island succeeded him and served from 28 July 1960 to 30 June 1966, and later acted as Administrator back on Cocos and on Norfolk Island. In 1974, Ken Mullen wrote

15000-417: Was detached from the convoy escort to investigate. Sydney spotted the island and Emden at 09:15, with both ships preparing for combat. At 11:20, the heavily damaged Emden beached herself on North Keeling Island . The Australian warship broke to pursue Emden ' s supporting collier , which scuttled herself, then returned to North Keeling Island at 16:00. At this point, Emden ' s battle ensign

15125-776: Was in fact Scottish] and HIS family, with about sixty or seventy mulattos from the Cape of Good Hope , live on one of the islands. Captain Ross, the governor, is now absent at the Cape." The islands were annexed by the British Empire in 1857. This annexation was carried out by Captain Stephen Grenville Fremantle in command of HMS  Juno . Fremantle claimed the islands for the British Empire and appointed Ross II as Superintendent. In 1878, by Letters Patent ,

15250-557: Was made official by the Cocos Islands Act 1955 ( 3 & 4 Eliz. 2 . c. 5). The territory's Malay name is Pulu Kokos (Keeling) . Sign boards on the island also feature Malay translations. The Cocos (Keeling) Islands consist of two flat, low-lying coral atolls with an area of 14.2 square kilometres (5.5 sq mi), 26 kilometres (16 mi) of coastline, a highest elevation of 5 metres (16 ft) and thickly covered with coconut palms and other vegetation. The climate

15375-635: Was preferred by both the islanders and the Australian government. A change in government in Canberra following the March 1983 Australian elections delayed the vote by one year. While the Home Island Council stated a preference for a traditional communal consensus "vote", the UN insisted on a secret ballot. The referendum was held on 6 April 1984, with all 261 eligible islanders participating, including

15500-526: Was revived in the latter part of World War II for the Western Pacific. Formal naming schemes have subsequently been introduced for the North and South Atlantic, Eastern, Central, Western and Southern Pacific basins as well as the Australian region and Indian Ocean. At present, tropical cyclones are officially named by one of twelve meteorological services and retain their names throughout their lifetimes to provide ease of communication between forecasters and

15625-615: Was still flying: usually a sign that a ship intends to continue fighting. After no response to instructions to lower the ensign, two salvoes were shot into the beached cruiser, after which the Germans lowered the flag and raised a white sheet . Sydney had orders to ascertain the status of the transmission station, but returned the next day to provide medical assistance to the Germans. Casualties totaled 134 personnel aboard Emden killed, and 69 wounded, compared to four killed and 16 wounded aboard Sydney . The German survivors were taken aboard

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