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The 1947 Sydney hailstorm was a natural disaster which struck Sydney, Australia, on 1 January 1947. The storm cell developed on the morning of New Year's Day, a public holiday in Australia, over the Blue Mountains, hitting the city and dissipating east of Bondi in the mid-afternoon. At the time, it was the most severe storm to strike the city since recorded observations began in 1792.〔〔Newman (1947), p. 23.〕 The high humidity, temperatures and weather patterns of Sydney increased the strength of the storm. The cost of damages from the storm were, at the time, approximately GB£750,000 (US$3 million); this is the equivalent of around A$45 million in modern figures.〔Reuters (1947), p. 4.〕 The supercell dropped hailstones larger than in diameter,〔Whitaker (2005), p. 98.〕〔Lee, ''et al.'' (2000), p. 579.〕 with the most significant damage occurring in the central business district and eastern suburbs of Sydney.〔Whitaker (2005), p. 95.〕〔 The event caused around 1000 injuries, with between 200 and 350 people requiring hospitalisation or other medical attention, predominantly caused by broken glass shards.〔〔Emergency Management Australia (2007).〕 The majority of severe injuries reported were suffered by people on Sydney's beaches, where many were without shelter.〔Whitaker (2005), p. 94.〕 The size of the hailstones were the largest seen in Sydney for 52 years, until the 1999 Sydney hailstorm caused A$1.7 billion in insured damage in becoming the costliest natural disaster in Australian history.〔 ==Conditions and climatology== During the spring and summer, conditions along the east coast of Australia are highly conducive for the formation of hailstorms. The variation of air temperature in the atmosphere; with warm and humid air close to the ground and colder air above it causes instability, and the cold upper atmosphere temperatures allow the precipitation to fall in solid form as hailstones.〔Whitaker (2005), p. 93.〕 Since records began in 1791, hailstorms in the month of January form approximately 13% of the total number of hailstorms in the Sydney metropolitan area, and over 15% of all events with 'large hail'.〔Schuster, ''et al.'' (2005a), pp. 1641–1643.〕 Hailstorms have a history of significant damage in Australia. Since records on insured losses began in 1967, four hailstorms—Sydney in 1986, 1990 and 1999, as well as Brisbane in 1985—have featured on the top ten list of most insured damages caused by a single Australian natural disaster. Hailstorms caused more than 30% of all insured damages inflicted as a result of natural disasters in Australia during this period, and around three quarters of all hailstorm damage has occurred in New South Wales.〔Schuster, ''et al.'' (2005b), p. 1.〕 The conditions on New Year's Day, 1947 were meteorologically sound for the formation of a storm. The day was hot and humid, with the maximum temperature recorded during the day being and humidity reaching 73%.〔Newman (1947), p. 27.〕 Many Sydneysiders travelled to the beaches along the coastline to benefit from the afternoon sea breeze. The general weather pattern for Sydney in summer is movement from the west to the east—from over the Blue Mountains to across the city and into the Tasman Sea.〔 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「1947 Sydney hailstorm」の詳細全文を読む スポンサード リンク
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