Page:Hunt - The climate and weather of Australia - 1913.djvu/11



Australia extends both sides of the Tropic of Capricorn from 10° S. latitude to 45° S. latitude. The greater portion lies south of the Tropic, and hence has a generally temperate climate. At the same time the range of 35° in latitude implies a very great difference between the north and south of the Continent, which justifies the remark that Port Darwin has a climate resembling that of Trinidad, while Tasmania has a typically cool, moist climate like that of England.

In addition to these extremes due to difference of latitude, there are many diversities due to the great breadth of the Continent along the tropic. Here Australia is 2,400 miles from west to east, so that a great portion of its surface lies remote from the influences of the sea. In this respect Australia differs markedly from the other southern land masses; for South America lies in a typically meridional direction and South Africa is only 1,400 miles across at the Southern Tropic. This factor of location is of extreme importance, for the climatic regions into which any large area can be subdivided depend essentially on the "lie of the land" with respect to the surrounding oceans, dominant winds, and other permanent influences.

In area Australia is about three-quarters that of Europe and contains (with Tasmania) 2,974,581 square miles. It is characterized by a very uniform outline, and by a lower average elevation than that of any other continent.

Both of these factors make for simplicity in the meteorology, for there are no tongues of water penetrating far into the interior, modifying the climate as does the Mediterranean in the Euro-African land mass. Moreover, Australia is absolutely devoid of large freshwater areas, and the salty lakes of Southern Australia do not appear to affect the climate of the surrounding area.

The average elevation of Australia is probably somewhat, under 1,000 feet. Although, as will be seen in Section VII., the more important positive land forms such as the Darling, Macdonnell, and Flinders Ranges, the Blue Mountains and Australian Alps have a great effect on the local distribution of rain, they do not act as primary agents in determining the climates of Australia. For instance, there is no such marked division as in the windward wet province of Western U.S.A., or the intramontane dry area of the Southern Rockies. As will be seen, however, similar types on a smaller scale are to be recognised in Australia (vide Section VII.).