Page:EB1911 - Volume 02.djvu/996

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946
[CLIMATE
AUSTRALIA

district with from 5 to 10 in. annual rainfall. The south-western angle of the continent, bounded by a line drawn diagonally from Jurien river to Cape Riche, has an average of from 30 to 40 in. annual rainfall, diminishing to about 20 to 30 in. in the country along the diagonal line. The remainder of the south and west coast from 124° E. to York Sound in the Kimberley district for a distance of some 150 m. inland has a fall ranging from 10 to 20 in. The 10 to 20 in. rainfall band circles across the continent through the middle of the Northern Territory, embraces the entire centre and south-west of Queensland, with the exception of the extreme south-western angle of the state, and includes the whole of the interior of New South Wales to a line about 200 m. from the coast, as well as the western and northern portions of Victoria and South Australia south of the Murray.

The area of Australia subject to a rainfall of from 10 to 20 in. is 843,000 sq. m. On the seaward side of this area in the north and east is the 20 to 30 in. annual rainfall area, and still nearer the sea are the exceptionally well-watered districts. The following table shows the area of the rainfall zones in square miles:—


Rainfall. Rainfall Areas
in sq. m.
Under 10 inches
10 to 20  ”
20 to 30  ”
30 to 40  ”
40 to 50  ”
50 to 60  ”
60 to 70  ”
Over 70  ”


1,219,600
843,100
399,900
225,700
140,300
47,900
56,100
14,100
————
Total2,946,700


The tropic of Capricorn divides Australia into two parts. Of these the northern or intertropical portion contains 1,145,000 sq. m., comprising half of Queensland, the Northern Territory, and the north-western divisions of Western Australia. The whole of New South Wales, Victoria and South Australia proper, half of Queensland, and more than half of Western Australia, comprising 1,801,700 sq. m., are without the tropics. In a region so extensive very great varieties of climate are naturally to be expected, but it may be stated as a general law that the climate of Australia is milder than that of corresponding lands in the northern hemisphere. During July, which is the coldest month in southern latitudes, one-half of Australia has a mean temperature ranging from 45° to 61°, and the other half from 62° to 80°. The following are the areas subject to the various average temperatures during the month referred to:—


Temperature
Fahr.
Area
in sq. m.
45°-50°
50°-55°
55°-60°
60°-65°
65°-70°
70°-75°
75°-80°
18,800
506,300
681,800
834,400
515,000
275,900
24,500


The temperature in December ranges from 60° to above 95° Fahr., half of Australia having a mean temperature below 84°. Dividing the land into zones of average summer temperature, the following are the areas which would fall to each:—


Temperature
Fahr.
Area
in sq. m.
60°-65°
65°-70°
70°-75°
75°-80°
80°-85°
85°-90°
90°-95°
95° and over
67,800
63,700
352,300
439,200
733,600
570,600
584,100
135,400


Judging from the figures just given, it must be conceded that a considerable area of the continent is not adapted for colonization by European races. The region with a mean summer temperature in excess of 95° Fahr. is the interior of the Northern Territory north of the 20th parallel; and the whole of the country, excepting the seaboard, lying between the meridians of 120° and 140°, and north of the 25th parallel, has a mean temperature in excess of 90° Fahr.

The area of Australia is so large that the characteristics of its climate will not be understood without reference to the individual states. About one-half of the colony of Queensland lies in the tropics, the remaining area lying between the Queensland. tropic and 29° S. The temperature, however, has a daily range less than that of other countries under the same isothermal lines. This circumstance is due to the sea-breezes, which blow with great regularity, and temper what would otherwise be an excessive heat. The hot winds which prevail during the summer in some of the other colonies are unknown in Queensland. Of course, in a territory of such large extent there are many varieties of climate, and the heat is greater along the coast than on the elevated lands of the interior. In the northern parts of the colony the high temperature is very trying to persons of European descent. The mean temperature at Brisbane, during December, January and February, is about 76°, while during the months of June, July and August it averages about 60°. Brisbane, however, is situated near the extreme southern end of the colony, and its average temperature is considerably less than that of many of the towns farther north. Thus the winter in Rockhampton averages nearly 65°, while the summer heat rises almost to 85°; and at Townsville and Normanton the average temperature is still higher. The average rainfall along the coast is high, especially in the north, where it ranges from 60 to 70 in. per annum, and along a strip of country south from Cape Melville to Rockingham Bay the average rainfall exceeds 70 in. At Brisbane the rainfall is about 50 in., taking an average of forty years. A large area of the interior is watered to the extent of 20 to 30 in. per annum, but in the west and south, more remote than from 250 to 300 m., there is a rainfall of less than 20 in.

Climatically, New South Wales is divided into three marked divisions. The coastal region has an average summer temperature ranging from 78° in the north to 67° in the south, with a winter temperature of from 59° to 52°. Taking the New
South
Wales.
district generally, the difference between the mean summer and mean winter temperatures may be set down as averaging not more than 20°, a range smaller than is found in most other parts of the world. Sydney, situated in latitude 33° 51′ S., has a mean temperature of 62.9° Fahr., which corresponds with that of Barcelona in Spain and of Toulon in France, the former of these being in latitude 41° 22′ N. and the latter in 43° 7′ N. At Sydney the mean summer temperature is 70.8° Fahr., and that of winter 53.9°. The range is thus 16.9° Fahr. At Naples, where the mean temperature for the year is about the same as at Sydney, the summer temperature reaches a mean of 74.4°, and the mean of winter is 47.6°, with a range 26.8°. The mean temperature of Sydney for a long series of years was spring 62°, summer 71°, autumn 64°, winter 54°.

Passing from the coast to the tableland, a distinct climatic region is entered. Cooma, with a mean summer temperature of 65.4°, and a mean winter temperature of 41.4°, may be taken as illustrative of the climate of the southern tableland, and Armidale of the northern. The yearly average temperature of the latter is scarcely 65.5°, while the summer only reaches 67.7°, and the winter falls to 44.4°.

The climatic conditions of the western districts of the state are entirely different from those of the other two regions. The summer is hot, but on the whole the climate is very healthy. The town of Bourke, lying on the upper Darling, may be taken as an example of many of the interior districts, and illustrates peculiarly well the defects as well as the excellencies of the climate of the whole region. Bourke has exactly the same latitude as Cairo, yet its mean summer temperature is 1.3° less, and its mean annual temperature 4° less than that of the Egyptian city. New Orleans, also on the same parallel, is 4° hotter in summer. As regards winter temperature Bourke leaves little to be desired. The mean winter reading of the thermometer is 54.7, and accompanied as this is by clear skies and an absence of snow, the season is both pleasant and invigorating. The rainfall of New South Wales ranges from an annual average of 64 in. at various points on the northern coast, and at Kiandra in the Monaro district, to 9 in. at Milparinka in the trans-Darling district. The coastal districts average about 42 in. per annum, the tablelands 32 in., and the western interior has an average as low as 20 in. At Sydney, the average rainfall, since observations were commenced, has been 50 in.

The climate of Victoria does not differ greatly from that of New South Wales. The heat, however, is generally less intense in summer, and the cold greater in winter. Melbourne, which stands in latitude 37° 50′ S., has a mean temperature of 57.3°, Victoria. and therefore corresponds with Washington in the United States, Madrid, Lisbon and Messina. The difference between summer and winter is, however, less at Melbourne than at any of the places mentioned, the result of a long series of observations being spring 57°, summer 65.3°, autumn 58.7°, and winter 49.2°. The highest recorded temperature in the shade at Melbourne is 110.7°, and the lowest 27°, but it is rare for the summer heat to exceed 85°, or for the winter temperature in the daytime to fall below 40°. Ballarat, the second city of Victoria, lies above 100 m. west from Melbourne at a height of 1400 ft. above sea-level. It has a minimum temperature of 29°, and a maximum of 104.5°, the average yearly mean being 54.1°. The rainfall of Melbourne averages 25.58 in., the mean number of rainy days being 131.

South Australia proper extends over 26 degrees of latitude, and naturally presents considerable variations of climate. The coldest months are June, July and August, during which the temperature is very agreeable, averaging 53.6°, 51.7°, South Australia. and 54° in those months respectively. On the plains slight frosts occur occasionally, and ice is sometimes seen on the