The Paths of the Highs and Lows.
Here also data are very incomplete except for 1910, but the main features can be deduced from a study of the tracks of the disturbances in that year.
Australian weather is controlled by three belts of atmospheric eddies. In the north moving (generally) from west to east, along the Tropic of Capricorn, is a procession of low pressure systems which are usually termed monsoonal lows. (The term "Tropical" might be less ambiguous, for in winter, at any rate, there is little akin to monsoonal conditions in Australian low-pressure areas.)
South of latitude 40° is another series of cyclonic eddies probably secondaries strung along the great low-pressure belt of the Southern Ocean. These are called antarctic cyclones. Between the two lies the belt of anticyclones whose path, as we shall see, swings between latitude 30° and 42°, as the sun moves south and back again.
The general tracks of the disturbances are shown on the diagrams, Figs. 32—35 (for 1910), when three facts may be noted in their characteristics. The tropical belt is much more irregular, the paths being often recurved. This series is never well developed in winter, the months of April, May, June, July, and August being generally free from these disturbances.
| Month. | Anticyclones. | Tropicals. | Antarctics. | |||
| No. | Remarks. | No. | Remarks. | No. | Remarks. | |
| January | 5 | 5 | Knot south of Hall's Creek (2 on east coast) | 4 | ||
| February | 4 | 6 | Two tropical storms | 4 | ||
| March | 6 | Of considerable average intensity | 6 | Two of storm intensity in Queensland | 4 | Of slight intensity |
| April | 6 | 3 | Off north coast (none on land) | 8 | Only two noteworthy | |
| May | 6 | Greatest intensity in east, and tendency to slow down there also | 1 | Over north Tasman Sea | 6 | Including two of north-west origin |
| June | 4 | (Two intense. 30.5) | 3 | Slight intensity | 6 | Half of cyclone energy |
| July | 7 | Moderate. Tended to have axis north and south | 2 | Very slight | 5 | Large, slow, stormy off south-west |
| August | 8 | More energy than July (7 normal track) | 1 | Low intensity | 7 | Less intensity; rather quicker |
| September | 5 | (Three, 30.5) | 6 | (Two Pilbarra), (four Carpentaria) | 5 | (Two, vigourous) |
| October | 4 | (Two of considerable intensity) | 5 | Of slight intensity | 4 | Of marked energy |
| November | 6 | Generally slight, diverged to east | 4 | Very persistent. Much thunder | 7 | Quick movement |
| December | 8 | Of feeble intensity, except the last | 8 | Numerous but sluggish | 8 | Numerous. More rapid |
