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Cyclone Tracy was a tropical cyclone that devastated the city of Darwin, Northern Territory, Australia, from Christmas Eve to Christmas Day, 1974. It is the most compact cyclone or equivalent-strength hurricane on record in the Australian basin, with gale-force winds extending only from the centre and was the most compact system worldwide until 2008 when Tropical Storm Marco of the 2008 Atlantic hurricane season broke the record, with gale-force winds extending only from the centre. After forming over the Arafura Sea, the storm moved southwards and affected the city with Category 4 winds on the Australian cyclone intensity scale, while there is evidence to suggest that it had reached Category 3 on the Saffir-Simpson Hurricane Scale when it made landfall. Tracy killed 71 people, caused 837 million in damage (1974 dollars), or approximately 4.45 billion (2014 dollars). It destroyed more than 70 percent of Darwin's buildings, including 80 percent of houses.〔(【引用サイトリンク】title=Tropical cyclone extremes )〕 Tracy left more than 41,000 out of the 47,000 inhabitants of the city homeless prior to landfall and required the evacuation of over 30,000 people. Most of Darwin's population was evacuated to Adelaide, Whyalla, Alice Springs and Sydney, and many never returned to the city. After the storm passed, the city was rebuilt using more modern materials and updated building techniques. Bruce Stannard of ''The Age'' stated that Cyclone Tracy was a "disaster of the first magnitude ... without parallel in Australia's history." ==Meteorological history== On 20 December 1974, the United States' ESSA-8 environmental satellite recorded a large cloud mass centred over the Arafura Sea about northeast of Darwin. This disturbance was tracked by the Darwin Weather Bureau's regional director Ray Wilkie, and by senior meteorologist Geoff Crane. On 21 December 1974, the ESSA-8 satellite showed evidence of a newly formed circular centre near latitude 8° south and longitude 135° east.〔(【引用サイトリンク】 title=Meteorological Cyclones Information — Countdown to the impact of Cyclone Tracey )〕 Crane - the meteorological duty officer at the time - issued the initial tropical cyclone alert describing the storm as a tropical low that could develop into a tropical cyclone. Later in the evening, the Darwin meteorological office received an infrared satellite image from the National Oceanic and Atmospheric Administration's satellite, NOAA-4, showing that the low pressure had developed further and that spiralling clouds could be observed. The storm was officially pronounced a tropical cyclone at around 10 p.m. on 21 December, when it was around to the north-northeast of Cape Don (700 km or 435 mi northeast of Darwin).〔(【引用サイトリンク】 title=Meteorological Cyclones Information — Warnings issued for Cyclone Tracey )〕 Cyclone Tracy was first observed on the Darwin radar on the morning of 22 December.〔(【引用サイトリンク】url=http://www.bom.gov.au/cyclone/history/pdf/tracy.pdf )〕 Over the next few days, the cyclone moved in a southwesterly direction, passing north of Darwin on 22 December. A broadcast on ABC Radio that day stated that Cyclone Tracy posed no immediate threat to Darwin. However, early in the morning of 24 December, Tracy rounded Cape Fourcroy on the western tip of Bathurst Island, and moved in a southeasterly direction, straight towards Darwin. The bureau's weather station at Cape Fourcroy measured a mean wind speed of at 9 a.m that morning. By late afternoon on 24 December, the sky over the city was heavily overcast, with low clouds, and was experiencing strong rain.〔(【引用サイトリンク】url=http://www.ntl.nt.gov.au/online_resources/cyclone_tracy )〕 Wind gusts increased in strength; between 10 p.m (local time) and midnight, the damage became serious, and residents began to realise that the cyclone would not just pass by the city, but rather over it. On 25 December at around 3:30 a.m, Tracy's centre crossed the coast near Fannie Bay.〔 The highest recorded wind gust from the cyclone was , which was recorded around 3:05 a.m at Darwin Airport.〔 The anemometer (wind speed instrument) failed at around 3:10 a.m, with the wind vane (wind direction) destroyed after the cyclone's eye.〔 The Bureau of Meteorology's official estimates suggested that Tracy's gusts had reached 240 km/h (150 mph). The lowest air pressure reading during Tracy was , which was taken at around 4 a.m, by a Bureau staff member at Darwin Airport.〔 This was recorded during the eye of the cyclone.〔 From around 6:30 a.m, the winds began to ease, with the rainfall ceasing at around 8:30 a.m.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Cyclone Tracy」の詳細全文を読む スポンサード リンク
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