Australia is bisected by the tropic of Capricorn; much of Australia is closer to the equator than any part of the USA. Accordingly, the northern Australia enjoys a tropical climate, and southern Australia a temperate one.
The tropical states Queensland and the Northern Territory have highly predictable weather. In winter, typical daily maximums are from 20 to 24 degrees Celsius (68 to 75 degrees Fahrenheit) and rain is rare. The beaches and tropical islands of Queensland and the Great Barrier Reef are perhaps at their most pleasant at this time of year. Further south, the weather is less dependable; in Melbourne in August maximums as low as 13 (56F) degrees are possible, but can reach as high as 23 (72F) degrees.
In summer, the northern states are hotter and wetter, while the southern states are simply hotter, with temperatures up to 41 (105F) in Sydney, Adelaide, and Melbourne but generally between 25 and 33 - very pleasant indeed.
Snow is rare in the southernmost capitals Melbourne and Hobart, falling less than once every ten years, and in the other capitals it is unknown. However, there are extensive, well-developed ski fields in the Great Dividing Range, a few hours drive from Melbourne and Sydney. Late August marks the peak of the snow season, and the ski resorts are a popular destination; perhaps too popular for some tastes. An alternative skiing destination is New Zealand, which provides skiers with excellent snow and facilities at lower cost.
By far the largest part of Australia is desert or semi-arid – 40% of the landmass is covered by sand dunes. Only the south-east and south-west corners have a temperate climate and moderately fertile soil. The northern part of the country has a tropical climate: part is tropical rainforests, part grasslands, and part desert.
Rainfall is highly variable, with frequent droughts lasting several seasons. Occasionally a duststorm will blanket a region or even several states and there are reports of the occasional large tornado. Rising levels of salinity and desertification in some areas is ravaging the landscape.
Australia has had a relatively stable geological history. Geological forces such as Tectonic uplift of mountain ranges or clashes between tectonic plates occurred mainly in Australia's early history, when it was still a part of Gondwana. Because of its peaceful nature, erosion and weathering has heavily weathered Australia's surface and it is one of the flattest countries in the world.
Australia is situated in the middle of the tectonic plate, and therefore has no active volcanism, although it may sometimes receive minor earthquakes. The terrain is mostly heavily weathered, low plateau with deserts, rangelands and a fertile plain in southeast. Tasmania and the Australian Alps do not contain any permanent icefields or glaciers, although they may have existed in the past. The Great Barrier Reef, by far the world's largest coral reef, lies a short distance off the north-east coast. Mount Augustus, in Western Australia, is the largest monolith in the world.
Australia's tropical/subtropical location and cold waters off the western coast make most of western Australia a hot desert with aridity, a marked feature of greater part of the continent. These cold waters produce precious little moisture needed on the mainland. A 2005 study by Australian and American researchers [1] investigated the desertification of the interior, and suggested that one explanation was related to human settlers who arrived about 50,000 years ago. Regular burning by these settlers could have prevented monsoons from reaching interior Australia.