Time in Australia
Australia uses three main time zones: Australian Western Standard Time, Australian Central Standard Time, Australian Eastern Standard Time. Time is regulated by the individual state governments. Australia's external territories observe different time zones. Standard time was introduced in the 1890s. Before the switch to standard time zones, each local city or town was free to determine its local time, called local mean time. Now, Western Australia uses Western Standard Time. Daylight saving time is used in states in the south and south-east - South Australia, New South Wales, Victoria and the ACT, it is not used in Western Australia, the Northern Territory or Queensland. The standardisation of time in Australia began in 1892, when surveyors from the six colonies in Australia met in Melbourne for the Intercolonial Conference of Surveyors; the delegates accepted the recommendation of the 1884 International Meridian Conference to adopt Greenwich Mean Time as the basis for standard time. The colonies enacted time zone legislation, which took effect in February 1895.
The clocks were set ahead of GMT by 8 hours in Western Australia. The three time zones became known as Western Standard Time, Central Standard Time, Eastern Standard Time. Broken Hill in the far west of New South Wales adopted Central Standard Time due to it being connected by rail to Adelaide but not Sydney at the time. On 1 May 1899 at 12:00AM local time, South Australia advanced Central Standard Time by thirty minutes after lobbying by businesses who wanted to be closer to Melbourne time and cricketers and footballers who wanted more daylight to practice in the evenings disregarding the common international practice of setting one-hour intervals between adjacent time zones. Attempts to correct these oddities in 1986 and 1994 were rejected; when the Northern Territory was separated from South Australia and placed under the jurisdiction of the Federal Government, that Territory kept Central Standard Time. When the ACT was broken off from New South Wales, it retained Eastern Standard Time. Since 1899, the only major changes in Australian time zones have been the setting of clocks to one-half hour earlier than Eastern time on the territory of Lord Howe Island, Norfolk Island changing from UTC+11:30 to UTC+11:00 on 4 October 2015.
When abbreviating "Australian Central Time" and "Australian Eastern Time", in domestic contexts the leading "Australian" may be omitted. Though the governments of the states and territories have the power to legislate variations in time, the standard time within each of these is set related to Coordinated Universal Time as determined by the International Bureau of Weights and Measures and set by section 8AA of the National Measurement Act of 1960 of the Commonwealth. Australia has kept a version of the UTC atomic time scale since the 1990s, but Greenwich Mean Time remained the formal basis for the standard times of all of the states until 2005. In November 2004, the state and territory attorneys-general endorsed a proposal from the Australian National Measurement Institute to adopt UTC as the standard of all Australian standard times, thereby eliminating the effects of slight variations in the rate of rotation of the Earth that are inherent in mean solar time. All states have adopted the UTC standard, starting on 1 September 2005.
In Victoria, South Australia and the ACT, the starting and ending dates of daylight saving times are determined by proclamations, declarations, or regulation made by the State Governor or by the responsible minister. Such instruments may be valid for only the current year, so this section only refers to the legislation. In New South Wales and Western Australia, the starting and ending dates, if any, are to be set by legislation. Western Standard Time – UTC+08:00 Western Australia – Standard Time Act 2005Central Standard Time – UTC+09:30 South Australia – Standard Time Act 2009 and the Daylight Saving Act 1971 Northern Territory – Standard Time Act 2005Eastern Standard Time – UTC+10:00 Queensland – Standard Time Act 1894 New South Wales – Standard Time Act 1987 No 149 Australian Capital Territory – Standard Time and Summer Time Act 1972 Victoria – Summer Time Act 1972 Tasmania – Standard Time Act 1895 and the Daylight Saving Act 2007 The choice of whether to use DST is a matter for the governments of the individual states and territories.
However, during World War I and World War II all states and territories used daylight saving time. In 1968 Tasmania became the first state in peacetime to use DST, followed in 1971 by New South Wales, Queensland, South Australia, the Australian Capital Territory. Western Australia and the Northern Territory did not adopt it. Queensland abandoned DST in 1972. Queensland and Western Australia have used DST during the past 40 years during trial periods; the main DST zones are the following: Central Daylight Saving Time – UTC+10:30, in South Australia Eastern Daylight Saving Time – UTC+11:00, in New South Wales, the ACT, TasmaniaDuring the usual
1971–72 Australian region cyclone season
The 1971–72 Australian region cyclone season was a active tropical cyclone season. Tropical Cyclone Rhoda existed from October 20 to October 26. Kitty, 2 to 5 December 1971 in the Arafura Sea Sally, 3 to 13 December 1971 crossed coast near Broome, Western Australia. Tropical Cyclone Althea was a Category 4 cyclone when it hit the coast some 50 km north of Magnetic Island and Townsville in North Queensland on December 24, 1971. Althea produced peak gust wind speeds between 145 miles per hour. Three people died and property damage was estimated at A$115 million loss. On Magnetic Island 90 % of the houses were destroyed. In Townsville houses were lifted from their foundations and most trees stripped of foliage. Althea was notable at the time, as it had struck a major city. Although there was a dangerous storm surge associated with TC Althea little flooding occurred because the cyclone made landfall on a low tide. However, the combination of storm surge and wave action demolished The Strand sea wall and houses in low-lying areas were inundated with up to 0.6 metres of water.
Bronwyn, 3 to 12 January 1972 in Gulf of Carpentaria Carlotta, 5 to 21 January 1972 well off Queensland Wendy, 30 January to 9 February 1972 intense off Queensland, possible pressure as low as 890hPa. Daisy, 7 to 14 February 1972 off Queensland, caused some flooding near Brisbane Tessie, 20 to 27 February 1972 in central Indian Ocean Vicky, 24 February to 4 March 1972 crossed Western Australian coast at Cockatoo Island. Angela, 29 February to 3 March 1972 near Cocos Island and Christmas Island Belinda, 20 to 30 March 1972 near Christmas Island Emily, 27 March to 4 April 1972 off Queensland, eight lives lost at sea Carol, 6 to 14 April 1972 in the central Indian Ocean. Faith, 11 to 23 April 1972 in Torres Strait and Coral Sea off Queensland Gail, 11 to 18 April 1972 well off Queensland Hannah, 8 to 11 May near Papua New Guinea Ida, 30 May to 3 June 1972 near Solomon Islands causing $70 million damage. Atlantic hurricane seasons: 1971, 1972 Eastern Pacific hurricane seasons: 1971, 1972 Western Pacific typhoon seasons: 1971, 1972 North Indian Ocean cyclone seasons: 1971, 1972
Great Australian Bight
The Great Australian Bight is a large oceanic bight, or open bay, off the central and western portions of the southern coastline of mainland Australia. Two definitions of the extent are in use – one used by the International Hydrographic Organization and the other used by the Australian Hydrographic Service; the IHO defines the Great Australian Bight as having the following limits: On the North. The south coast of the Australian mainland. On the South. A line joining West Cape Howe Australia to South West Cape, Tasmania. On the East. A line from Cape Otway, Victoria to King Island and thence to Cape Grim, the northwest extreme of Tasmania; the AHS defines the bight with a smaller area, from Cape Pasley, Western Australia, to Cape Carnot, South Australia - a distance of 1,160 kilometres. Much of the bight lies due south of the expansive Nullarbor Plain, which straddles South Australia and Western Australia; the Eyre Highway passes close to the cliffs of the bight between the Head of the Eucla. Outside of Australia, the Great Australian Bight is considered part of the Indian Ocean.
The AHS considers it to be part of the Southern Ocean, using the expanded Australian definition used for this ocean. The IHO in its Limits of Oceans and Seas includes the bight with the Indian Ocean, while Bass Strait and the Tasman Sea are included by IHO with the South Pacific Ocean in the 2002 draft. In the 1953 edition, IHO includes Bass Strait as part of the Indian Ocean; the Great Australian Bight was first encountered by European explorers in 1627 when a Dutch navigator François Thijssen sailed along its western margins. The coast was first charted by the English navigator Matthew Flinders in 1802, during his circumnavigation of the Australian continent. A land-based survey was accomplished by the English explorer Edward John Eyre; the bight came into existence when Gondwana broke apart and separated Antarctica from Australia around 50 million years ago. The coastline of the Great Australian Bight is characterised by cliff faces, surfing beaches and rock platforms, ideal for whale-watching.
This is a popular activity during the southern hemisphere winter, when increasing numbers of southern right whales migrate to the region from their summer feeding grounds in the Antarctic. The whales come to the Bight region to the Head of Bight, to calve and breed, do not feed until they return to the Antarctic, their numbers were depleted by whaling during the 19th Century, but have since recovered to some extent. The Nullarbor Plain, which borders much of the length of the Bight's coastline, is a former seabed, uplifted during the Miocene. Consisting of limestone, it is flat, has an arid or semi-arid climate with little rainfall, high summer temperatures and high evaporation rates, it has no surface drainage, but has a karst drainage system through cave formation in the underlying limestone. North of the Nullarbor lies the Great Victoria Desert, which has an internal drainage system terminating in numerous small salt lakes; the lack of surface runoff and terrestrial nutrients results in the shallow waters of the Great Australian Bight being low in nutrients, therefore oligotrophic, compared with many other continental shelves which support major fisheries.
Seasonal upwelling of deep ocean water along the coast of the Eyre Peninsula in the eastern part of the Bight brings nutrients to the surface waters, with the resulting fertility creating an important marine hotspot. The waters of the Great Australian Bight are biodiverse in zooplankton, due to a particular series of ocean currents. A literature review undertaken by SARDI on the Benthic Protection Zone of the Great Australian Bight Marine Park in 2003 states: "Upwelling events during summer and autumn produce cool patches of surface water along the coast of the southern Eyre Peninsula; these patches contain elevated nutrient concentrations and support enhanced levels of primary productivity. High densities of zooplankton to the northwest of the patches indicate that the prevailing southeasterly winds transport the products of this enhanced biological production into the central GAB; these plankton communities support the highest densities of small planktivorous fishes, including sardine and anchovy, in Australian waters.
Juvenile southern bluefin tuna migrate into the GAB annually to feed on these rich pelagic resources." As the nutrients are swept up from the deep water ocean floor and pushed in towards the coast, the food chain is injected with a massive influx of the bottom rung. There is not enough known about the full scope of species that dwell in or migrate to the Great Australian Bight, so more studies are required. "The Interim Marine and Coastal Regionalisation of Australia classification suggests that high biodiversity in the GAB may be explained by the presence of temperate species with eastern and western affinities, as well as “tropical stragglers” from northern regions. However, patterns of diversity vary between taxa. Mangroves are poorly represented due to the lack of estuaries. Seagrasses are confined to sheltered bays and the lees of reefs and islands due to the frequent disturbance of inshore habitats by large swells. In contrast, the macroalgal assemblage of the GAB is one of the world’s most diverse and includes >1200 species.
Over 90% of species in most invertebrate groups are endemic to southern Australia, but the proportion, confined to the GAB is unknown."There is still much research needed to understand the complex ecosystems of the Great Australian Bight and
Saffir–Simpson scale
The Saffir–Simpson hurricane wind scale the Saffir–Simpson hurricane scale, classifies hurricanes – Western Hemisphere tropical cyclones that exceed the intensities of tropical depressions and tropical storms – into five categories distinguished by the intensities of their sustained winds. To be classified as a hurricane, a tropical cyclone must have one-minute maximum sustained winds of at least 74 mph; the highest classification in the scale, Category 5, consists of storms with sustained winds over 156 mph. The classifications can provide some indication of the potential damage and flooding a hurricane will cause upon landfall; the Saffir–Simpson hurricane wind scale is based on the highest average wind over a one-minute time span and used only to describe hurricanes that form in the Atlantic Ocean and northern Pacific Ocean east of the International Date Line. Other areas use different scales to label these storms, which are called cyclones or typhoons, depending on the area; these areas use three-minute or ten-minute averaged winds to determine the maximum sustained winds—which is an important difference and makes direct comparison with storms scaled with the Saffir–Simpson method difficult.
There is some criticism of the SSHWS for not accounting for rain, storm surge, other important factors, but SSHWS defenders say that part of the goal of SSHWS is to be straightforward and simple to understand. The scale was developed in 1971 by civil engineer Herbert Saffir and meteorologist Robert Simpson, who at the time was director of the U. S. National Hurricane Center; the scale was introduced to the general public in 1973, saw widespread use after Neil Frank replaced Simpson at the helm of the NHC in 1974. The initial scale was developed by Herbert Saffir, a structural engineer, who in 1969 went on commission for the United Nations to study low-cost housing in hurricane-prone areas. While conducting the study, Saffir realized there was no simple scale for describing the effects of a hurricane. Mirroring the utility of the Richter magnitude scale for describing earthquakes, he devised a 1–5 scale based on wind speed that showed expected damage to structures. Saffir gave the scale to the NHC, Simpson added the effects of storm surge and flooding.
In 2009, the NHC made moves to eliminate pressure and storm surge ranges from the categories, transforming it into a pure wind scale, called the Saffir–Simpson Hurricane Wind Scale. The new scale became operational on May 15, 2010; the scale excludes flood ranges, storm surge estimations and location, which means a Category 2 hurricane that hits a major city will do far more cumulative damage than a Category 5 hurricane that hits a rural area. The agency cited various hurricanes as reasons for removing the "scientifically inaccurate" information, including Hurricane Katrina and Hurricane Ike, which both had stronger than estimated storm surges, Hurricane Charley, which had weaker than estimated storm surge. Since being removed from the Saffir–Simpson hurricane wind scale, storm surge predicting and modeling is now handled with the use of computer numerical models such as ADCIRC and SLOSH. In 2012, the NHC expanded the windspeed range for Category 4 by 1 mph in both directions, to 130–156 mph, with corresponding changes in the other units, instead of 131–155 mph.
The NHC and the Central Pacific Hurricane Center assign tropical cyclone intensities in 5 knot increments, convert to mph and km/h with a similar rounding for other reports. So an intensity of 115 kn is rated Category 4, but the conversion to miles per hour would round down to 130 mph, making it appear to be a Category 3 storm. An intensity of 135 kn is 250.02 km/h, according to the definition used before the change would be Category 5. To resolve these issues, the NHC had been obliged to incorrectly report storms with wind speeds of 115 kn as 135 mph, 135 kn as 245 km/h; the change in definition allows storms of 115 kn to be rounded down to 130 mph, storms of 135 kn to be reported as 250 km/h, still qualify as Category 4. Since the NHC had rounded incorrectly to keep storms in Category 4 in each unit of measure, the change does not affect the classification of storms from previous years; the new scale became operational on May 15, 2012. The scale separates hurricanes into five different categories based on wind.
The U. S. National Hurricane Center classifies hurricanes of Category 3 and above as major hurricanes, the Joint Typhoon Warning Center classifies typhoons of 150 mph or greater as super typhoons. Most weather agencies use the definition for sustained winds recommended by the World Meteorological Organization, which specifies measuring winds at a height of 33 ft for 10 minutes, taking the average. By contrast, the U. S. National Weather Service, Central Pacific Hurricane Center and the Joint Typhoon Warning Center define sustained winds as average winds over a period of one minute, measured at the same 33 ft height, and, the definition used for this scale. Intensity of example hurricanes is from both the time of the maximum intensity; the scale is logarithmic in wind speed, the top wind speed for Category “c” can be expressed as 83×10 miles per hour rounded to the nearest multiple of 5 – except that after the change mentioned above, Category 4 is now widened by 1 mph in each direction and that the
Tropical cyclone
A tropical cyclone is a rotating storm system characterized by a low-pressure center, a closed low-level atmospheric circulation, strong winds, a spiral arrangement of thunderstorms that produce heavy rain. Depending on its location and strength, a tropical cyclone is referred to by different names, including hurricane, tropical storm, cyclonic storm, tropical depression, cyclone. A hurricane is a tropical cyclone that occurs in the Atlantic Ocean and northeastern Pacific Ocean, a typhoon occurs in the northwestern Pacific Ocean. "Cyclone" refers to their winds moving in a circle, whirling round their central clear eye, with their 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 form over large bodies of warm water, they derive their energy through the evaporation of water from the ocean surface, which recondenses 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 fueled by horizontal temperature contrasts. Tropical cyclones are between 100 and 2,000 km in diameter; the strong rotating winds of 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, they form within 5° of the equator. Tropical cyclones are unknown in the South Atlantic due to a strong wind shear and a weak Intertropical Convergence Zone; the African easterly jet and areas of atmospheric instability which give rise to cyclones in the Atlantic Ocean and Caribbean Sea, along with the Asian monsoon and Western Pacific Warm Pool, are features of the Northern Hemisphere and Australia. Coastal regions are vulnerable to the impact of a tropical cyclone, compared to inland regions; the primary energy source for these storms is warm ocean waters, therefore these forms are strongest when over or near water, weaken quite over land.
Coastal damage may be caused by strong winds and rain, high waves, storm surges, the potential of spawning tornadoes. Tropical cyclones draw in air from a large area—which can be a vast area for the most severe cyclones—and concentrate the precipitation of the water content in that air into a much smaller area; this continual replacement of moisture-bearing air by new moisture-bearing air after its moisture has fallen as rain, which may cause heavy rain and river flooding up to 40 kilometres from the coastline, far beyond the amount of water that the local atmosphere holds at any one time. Though their effects on human populations are devastating, tropical cyclones can relieve drought conditions, they carry heat energy away from the tropics and transport it toward temperate latitudes, which may play an important role in modulating regional and global climate. Tropical cyclones are areas of low pressure in the troposphere, with the largest pressure perturbations occurring at low altitudes near the surface.
On Earth, the pressures recorded at the centers of tropical cyclones are among the lowest observed at sea level. The environment near the center of tropical cyclones is warmer than the surroundings at all altitudes, thus they are characterized as "warm core" systems; the near-surface wind field of a tropical cyclone is characterized by air rotating around a center of circulation while flowing radially inwards. At the outer edge of the storm, air may be nearly calm; as air flows radially inward, it begins to rotate cyclonically in order to conserve angular momentum. At an inner radius, air begins to ascend to the top of the troposphere; this radius is coincident with the inner radius of the eyewall, has the strongest near-surface winds of the storm. Once aloft, air flows away from the storm's center; the mentioned processes result in a wind field, nearly axisymmetric: Wind speeds are low at the center, increase moving outwards to the radius of maximum winds, decay more with radius to large radii.
However, the wind field exhibits additional spatial and temporal variability due to the effects of localized processes, such as thunderstorm activity and horizontal flow instabilities. In the vertical direction, winds are strongest near the surface and decay with height within the troposphere. At the center of a mature tropical cyclone, air sinks rather than rises. For a sufficiently strong storm, air may sink over a layer deep enough to suppress cloud formation, thereby creating a clear "eye". Weather in the eye is calm and free of clouds, although the sea may be violent; the eye is circular in shape, is 30–65 km in diameter, though eyes as small as 3 km and as large as 370 km have been observed. The cloudy outer edge of the eye is called the "eyewall"; the eyewall expands outward with height, resembling an arena foo
Willis Island
Willis Island is the only permanently inhabited island in the Coral Sea Islands Territory, an external territory of Australia, located beyond the Great Barrier Reef in the Coral Sea. The island is located some 450 kilometres east of Queensland, it is the southernmost of the Willis Islets, a group of three islands which with their associated sandy cays stretch in a NNE to SSW line for about 12 kilometres. Willis Island itself is aligned NW to SE and is about 500 metres long by 150 metres wide, 7.7 hectares in area, rising to about 9 metres above sea level. The Australian Bureau of Meteorology has a Weather station on the island. There are four weather observers, one of whom is Officer-in-Charge, one Technical Officer living on the island; the Willis Island weather monitoring station was established in 1921 and equipped with a radio transmitter in order to provide a cyclone early warning service for Queensland. The first officer in charge was John King Davis. On 2 February 2011, sometime shortly after 08:30 AEST, the eye of Cyclone Yasi moved directly over Willis Island as a Category 5 tropical cyclone.
Four station staff had been evacuated the previous day. A wind gust speed of 185 kilometres per hour was recorded by the weather station equipment before the anemometer failed; the barometric pressure fell to an exceptionally low 937.9 hectopascals. Around 9:00 am, radar data was disrupted. An hour communication with the island was cut off; the cyclone was so strong it cleared much of its vegetation. Limited services were restored on 17 February 2011. A Bureau of Meteorology spokeswoman said the core building sustained minor damage to the roof, deck covering and one of the solar panels. "The radome which protects the radar was destroyed and the radar itself sustained damage and needed to be replaced," she said. The associated storm surge damaged the power generator, sewage system and desalination equipment. Operation of the weather monitoring station was restored on 12 December 2011. Up to 2004 most of the infrastructure constructed in either 1950 or 1968 still existed. Maintenance and refurbishment had been an ongoing costly process.
The small parcel of land accommodated 8 buildings of varying structure as follows: Main building housing recreation, kitchen/dining, sleeping and equipment room constructed in 1950. Personal living accommodation was provided in a barracks-like wing between the meteorological office and the kitchen-living room area. Meteorological equipment included a defined equipment enclosure and a seven metre high radar tower plus dome. Other equipment included a desalination enviro-cycle sewage treatment plant. From 2005, the following new facilities and services have been constructed: Meteorological office, mess area, recreational area, powerhouse. Accommodation facilities caters for up to 10 visiting personnel. Meteorological equipment includes a defined equipment enclosure and a seven metre high radar tower plus dome. Other equipment includes enviro-cycle sewage treatment plant. Power generation comprises a hybrid system of a diesel generator combined with a wind generator and solar power. Rainwater harvesting has not been implemented due to the high level of marine bird life and guano deposits.
The station has a recreation room which includes amenities such as a pool table and table tennis, along with an outside sporting area and a home gym. There are opportunities for recreational fishing. A substantial library caters for all tastes. Two satellite television systems enable reception of Australian Channel 10 and the ABC, of free-to-air transmissions from countries such as Malaysia and Indonesia. Programming includes the American television channels CNN and MTV and an extensive video library completes the passive entertainment options. Occasional amateur radio operations occur in the Willis islets. Under DXCC rules Willis is considered to be a separate "entity" for award credit. A major DXpedition visited for several weeks in October 2008. Another operated here in November 2015. In the past, landfill was buried on the island, high winds and heavy seas from a cyclone would uncover parts of the waste. A major clean-up campaign was conducted in 2004 and 2005 to protect the sensitive areas such as the coral cays and sand dunes.
Today, all waste generated on the island, as well as any debris that washes ashore, is placed in bins and shipped back on the staff exchange vessel for appropriate disposal on the mainland. Tropical Cyclone Yasi uncovered a landfill site on the island, found to include some asbestos containing material; the area was remediated and all waste was removed from the island. Three formal Occupational Health and Safety investigations on Willis Island have been undertaken by independent assessors – GHD and Parsons Brinkerhoff; these investigation
