Comparison of Climatic Regions.
Each of the four or five main divisions of Australia which have been described in the foregoing can be paralleled by simlar regions in other parts of the world. These are briefly summarized in the following table (based on Herbertson and Koepper):—
| Australian. | Extra-Australian. |
| 1. Summer rain region | Sudan, Brazil (like the wetter north portion); and South Siberia and Argentine (like the drier south-east portion) |
| 1a. North-east coast (trade wind region) | Florida, South China coast |
| 2. Dry region | Kalahari, Atacama, Sahara, Arizona |
| 3. Uniform rain region | Uruguay, Cape Colony (south-east) |
| 3a. Autumn maximum | Eastern U.S.A.,Natal, South-east Brazil |
| 4. Winter rain region | Cape Colony (west), Chili, California, and Mediterranean lands |
IX. CHARACTERISTICS OF DROUGHT YEARS IN AUSTRALIA.
As would naturally be expected, years drier than normal in Australia are, in general, years with air pressure above normal, and vice versâ. A comparison of the barometric and rain records for the various capital cities bears this out, though in some cases with only moderate emphasis. For example, Melbourne gives 30 cases in favour of this rule and 24 against it. Sydney, 36 for, 18 against; Brisbane, 20 for to 5 against; Adelaide, 40 for to 15 against; Perth, 28 for, 9 against; and Hobart, 22 for, and 18 against. The probability of this rule holding seems to vary with the latitude, being greater as the tropic is approached. Thus the probability that this will be so, for Hobart is .55, for Melbourne .56, for Adelaide .73, for Sydney .66, for Perth .76, and for Brisbane .80.
Confining attention to the period since 1880, the information for previous years being rather too scanty for any adequate review of their peculiarities, the principal drought years affecting the inland areas of South Australia, Victoria, and New South Wales, were 1881, 1884, 1885, 1888, 1895, 1896, 1897, 1899, 1902, 1907, and 1911. In considering drought years, attention is directed rather to the failure of the rains during the critical periods for grass and crops, which may be taken as extending from 1st April to 31st October. The small annual rain totals for all but one of these constituted them drought years in any case, the exception, and a very remarkable one, being 1911, which, if the total rainfall alone is considered, stands out as one of the wettest years on record for Victoria, owing to two tremendous rainfalls in February and March. From July onward it was extremely dry, as were also the first five months of 1912. The years 1884 and 1885 were not universally bad, the former being very dry only in the eastern States, and the latter in South Australia.
The following tables show for Melbourne and Adelaide the mean pressure and temperature departures from the normal for each month of these years. As may be seen from these, considering the year as a whole, for Melbourne,
