The Commonwealth of Australia consists of a large island continent lying between 11° and 39°S and the large offshore island of Tasmania between 41° and 44°S.
The country is only a little smaller than the United States but its sparse population is comparable with that of Canada. Most of Australia's population lives in the climatically more favoured eastern, southern, and southwestern coastal areas. Between half and two-thirds of the country is desert or scrubland with a low and unreliable rainfall, and this region is almost uninhabited. Nearly half of Australia lies within the tropics.
The greater part of Australia consists of flat or gently undulating plains 150-600 m/500-2,000 ft above sea level.
The east coast is backed by an almost continuous range of hills or mountains which are highest on the border between New South Wales and Victoria in the south. Here the Snowy Mountains include the highest peak in Australia at 2,225 m/7,300 ft.
This is the only part of the country to experience significant snowfall, and even here the snow does not lie throughout the year. For much of the year the east coast is exposed to the persistent and regular southeast trade winds blowing off the Pacific, and this is the wettest part of the country. To the west of these eastern highlands rainfall decreases towards the interior, which is desert.
Central Australia is situated in the latitude of the persistent subtropical anti-cyclonic belt and this is another reason for its dryness. In this respect it resembles the Sahara and Kalahari deserts of Africa, though it is not quite as rainless as the Sahara.
The wettest districts of Australia form a crescent around the 'dry heart' of the country. In the north and northeast, where temperatures are tropical, rainfall follows the sun and there is a very clear maximum fall at the time of high sun between November and April.
During this season winds on the north coast are from the northwest: the Australian monsoon, the counterpart of the out-blowing Asiatic winter monsoon. These winds have become hot and humid as they cross the equatorial seas around Indonesia and the Philippines.
The east and southeast coasts of Australia get rain in all seasons, with rather more in the summer. The south and southwest coasts of South and Western Australia are affected by westerly cyclonic disturbances during the cooler winter season and have their maximum rainfall at this time. The desert region reaches the coast between 18° and 30°S on the west coast and between 125° and 135°E on the south coast so that the wetter coastal fringe of the country is not continuous.
Much of Australia is warm or hot throughout the year, and even along the cooler southern coasts the winters are mild rather than cold. Only Tasmania, which is in the same latitude as New Zealand, has a temperate climate comparable with that of Britain or northwest Europe.
Very high temperatures may occasionally occur almost anywhere in Australia when winds blow out from the interior and 'import' the high temperatures and low humidity of the interior desert to the coastal regions. Only Tasmania escapes such extremes of heat; it also has abundant rain around the year. The combination of prolonged heat waves and drought is one of the main climatic hazards of much of Australia and is the main cause of the bush fires, which may rage for days.
Tropical cyclones, similar to the typhoons of the North Pacific and South China Sea, occur two or three times each year in the seas to the northeast and northwest of Australia. The northern part of the Queensland coast and the north and west coasts from Darwin southwards are affected by the torrential rain and sometimes by the very high winds near the storm centre. On the northwest coast of Australia these storms go by the Australian Aboriginal name of 'willy-willies'.
Because much of the country is fairly low and flat, contrasts of weather and climate are gradual and there are few sharp local changes. For a more detailed description the country can be divided into four climatic regions (in addition to Tasmania which is more temperate in climate): the tropical regional of the north and northeast, southeastern Australia, southern and western Australia, and the desert and semi-arid regions of central Australia. These climatic regions rarely coincide with state boundaries. Only Victoria and Tasmania, the two smallest states, do not include part of the dry interior.
The Tropical North and Northeast
Including (with towns and cities in parentheses) the Great Barrier Reef, the northern extremities of Western Australia, Northern Territory (Darwin), Queensland (Cairns, Townsville).
This region consists of the coastlands of Queensland, the Northern Territory and Western Australia, and the inland districts, which have more than 500 mm/20 in annual rainfall. On the east coast its southern limit is rather to the north of Brisbane but, as the table for Brisbane shows, winter temperatures here are very close to those normally regarded as constituting a tropical climate.
Brisbane differs from places farther north in that it gets some rain in all months, as distinct from Townsville and Darwin, which are more typically tropical in having a virtual drought during the low sun period. This region is typically tropical in having a combination of heat, rainfall, and high humidity during the summer or high sun period of November to March. At this time the weather can be distinctly sultry and oppressive. The higher temperatures and lower humidity experienced inland towards the dry interior are more bearable than the sticky heat of the coast.
Like most of Australia, this region has a very sunny climate with daily sunshine hours averaging six to seven hours during the dry months. Annual sunshine hours are similar to those found in California or the European Mediterranean lands.
Including (with towns and cities in parentheses) the southeastern corner of Queensland (Brisbane), Victoria (Melbourne), the greater part of New South Wales (Sydney, Bourke, Canberra), but excluding the drier western and northwestern part of this state.
This part of Australia has attracted the most extensive colonization by Europeans since the first settlement near Sydney in the late 18th century. It has a climate that is best described as warm-temperate with no real cold season, warm-to-hot summers, and rain well distributed throughout the year. The weather can be changeable at all times of the year and summers are liable to prolonged heat waves and droughts. The hazard of drought is much greater inland as the average rainfall decreases; prolonged drought and unreliable rainfall have been persistent themes in the settlement history of Australia.
Cold spells are brief and never severe on the coast, as the tables for Sydney and Melbourne show. Temperatures can drop much lower inland (see the tables for Canberra and Bourke). The temperatures for Canberra also illustrate the effect of a moderate altitude in lowering the winter minimum temperatures.
The low annual rainfall at Bourke illustrates the transition to the semi-arid conditions of the interior. It should be noted that the extreme maximum temperatures at Bourke are higher than those recorded in the tropical regions of the north and that both Sydney and Melbourne occasionally record temperatures well above 100°F/38°C.
Latitude here begins to affect the number of sunshine hours. Summer sunshine averages eight to nine hours a day in summer but only five to six in winter. At Melbourne, which gets more cloud and disturbed weather despite a lower rainfall, sunshine hours per day in winter are only three to four as against seven to eight in summer.
Southern and Southwestern Australia
Including (with towns and cities in parentheses) the area around Spencer Gulf in South Australia (Adelaide), southwestern Western Australia (Perth), parts of western Victoria.
This region consists of two small districts separated by the desert coast along the Great Australian Bight where the annual rainfall is below 250 mm/10 in. These regions are distinctive in having a Mediterranean climate.
Rainfall is moderate and falls mainly in the winter. Summers are warm to hot with an almost complete drought. The winter season gets much changeable weather, associated with cyclonic disturbances in the westerly wind belt which affects the south of Australia during this season.
The tables for Perth and Adelaide are representative of the wetter parts of these two districts. The mildness of the winter is illustrated by the fact that at neither place has the temperature ever fallen below freezing point.
The winter maximum of rainfall is very clearly marked at both places, but Perth gets a much heavier rainfall than Adelaide. The extent of this wet winter climate is rather greater in Western Australia than it is in South Australia, where the transition to desert inland is quite rapid. During the hot, dry summer, temperatures can occasionally rise very high: over 110°F/43°C. In summer these areas average between nine and ten hours of sunshine per day as compared with five to six in winter.
The Interior and Semi-desert
Including (with towns and cities in parentheses) the inland part of Northern Territory (Alice Springs, Ayers Rock), the greater part of Western Australia (Kalgoorlie), South Australia.
This is the most extensive climatic region of Australia and includes parts of each mainland state with the exception of Victoria. In the north it can be roughly defined by the 500 mm/20 in annual rainfall limit and in the south by the 300 mm/12 in annual rainfall line.
Rainfall is everywhere scanty and unreliable. The cool-season rainfall of the south is much more effective than the hot-season rainfall of the tropical north of Australia. Compare the table for Alice Springs, which is almost in the centre of the continent, and that for Kalgoorlie which is on the desert margin of Western Australia.
Like most continental interiors there is a considerable daily and seasonal change of temperature. Both Alice Springs and Kalgoorlie have experienced temperatures below freezing and at Alice Springs, which is almost within the tropics, they have fallen below freezing point in several winter months.
These desert areas are the sunniest part of Australia. Daily sunshine hours average nine to ten around the year. The high temperatures are to some extent mitigated by low humidity. Occasional dust storms during strong winds are a minor climatic hazard.
This rugged island, a little smaller than Scotland, is mountainous so there are quite big differences in weather and climate between the coastal regions and the interior. The highest mountains rise to over 1,500 m/2,500 ft and, on the west, are fully exposed to the stormy westerly winds which bring heavy rainfall - over 2,500 mm/100 in a year in places.
The eastern lowlands, represented by the table for Hobart, have a much lower rainfall of between 500 mm/20 in and 750 mm/30 in a year. The weather is changeable and often disturbed around the year.
Tasmania's climate is strongly influenced by the relative warmth of the southern ocean so that winters are mild at sea level and summers rarely excessively hot. Its climate and weather throughout the year are rather similar to that of northwest Europe, particularly Brittany or northwest Spain.
Daily sunshine hours range from four to five in winter to seven or eight in summer, sunnier than much of northwest Europe. The occasional high temperatures in summer (over 100°F or 38°C) occur when very warm air is drawn southwards from the central region of Australia. Although snow is often heavy in winter on the mountains it does not lie throughout the summer.
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