Page:Hunt - The climate and weather of Australia - 1913.djvu/103

The table shows that Coolgardie lies in the winter rain region, and that Peak Hill gets its infrequent rains both in winter and summer, while Pilbara, so far as frequency is concerned, has a slight summer maximum and a more characteristic spring minimum.

Direction of Rain Winds.

The wind directions tabulated refer to the dominant winds over the whole rain area ("smear" is used for such local rain) due to one particular storm or set of controls.

The rain winds affecting the dry interior are chiefly from the north to north-east octant, veering to the north-west in part in the colder months. But the south-west and south winds also exercise a beneficial effect, especially in the colder months:—

Fig. 75.

Summer.		Autumn.		Winter.		Spring.
N.E. = 8 N.  = 2	$\scriptstyle {\left.{\begin{matrix}\ \\\ \end{matrix}}\right\}\,}$ 10	N.W. = 7 N.  = 3 N.E. = 6	$\scriptstyle {\left.{\begin{matrix}\ \\\\\ \ \end{matrix}}\right\}\,}$ 16	N.  = 15 N.W. =  4 N.E. =  4	$\scriptstyle {\left.{\begin{matrix}\ \\\\\ \ \end{matrix}}\right\}\,}$ 23	N.E. = 10 S.W. = 10 S.   =  4	$\scriptstyle {\left.{\begin{matrix}\ \\\\\ \ \end{matrix}}\right\}\,}$ 14
S.  = 6 S.W. = 2	$\scriptstyle {\left.{\begin{matrix}\ \\\ \end{matrix}}\right\}\,}$ 8	S.W. = 5		S.W. = 11
Others 3		Others 3		Others 4		Others 3

Pressure Systems and their Distribution.

The conditions leading to the fall of rain in the interior of Western Australia are by no means always of the same type. The most striking feature shown by the analysis is the persistence of one type throughout a season in one year which may not occur in the same season next year. For instance, in January and February, 1911, there was a greater distance between the low (over Condon) and the high to the south-east (south of Mt. Gambier, &c.) than usual. In June and July, 1910, and 1912, the high covered most of Eastern Australia, while the low off Albany led to rains over the gold-fields. In these two months during the intermediate year 1911, there seemed a tendency for the succeeding high to appear sooner off North-west Cape and control the situation. The same "habit" is shown in other months, but not to the extent of obliterating the characteristic features of the distribution of highs and lows each month.

There is perhaps no need to emphasize the fact that, in an immense area like Australia, each climatological division exhibits as diverse features as does, for instance, the whole of the British Isles.