4 AUSTRALIAN WEATHER. 



heated as it blows over Central Australia, and becomes the true 

 hot wind of the Southern Colonies. This also explains the sudden 

 shift from hot northerly to the cold southerly wind, blowing on 

 the following side of the A depression. 



11. Cyclonic storms are very unusual, and do not appear more 

 than once in two or three months. These come from north-east 

 to east, or from the north-west coast across the Australian 

 continent to the sea at the Great Bight, thence they travel 

 eastward. They do not seem in any sense to be part of our 

 weather system, but to be offsets from tropical storms. 



The depression between anticyclones is essentially a A depres- 

 sion, both in the shape of the isobars and in the sudden change of 

 wind which follows the passage of the lowest pressure. 



It is, of course, impossible here to pass in review all the 1,400 

 Weather Charts which have contributed to these deductions ; and 

 I have, therefore, selected for reproduction here a set of eight 

 Weather Charts in which the passage of an average cyclone is 

 clearly depicted (Diagrams 1 to 8). The isobars have been repro- 

 duced on a convenient and small scale, and they show much better 

 than any description what the ordinary fine weather sequence of 

 events is. Attention may, however, be called to one or two points. 

 No. 1 diagram shows the incoming anticyclone well established on 

 the coast of Western Australia, with a passing A depression in 

 front of it extending over the southern parts of South Australia, 

 Victoria, and New South Wales. No. 2 shows the twenty-four 

 hours' forward motion and the closing up of the isobars as they 

 reach the east coast mountain range. Nos. 3 and 4 show the further 

 progress of the high pressure and the decided effect of New 

 Zealand mountains in intensifying the A depression. No. 5. 

 As on Sunday we get no telegrams, probable isobars have been 

 drawn. No. 6 shows the anticyclone over New South Wales, and 

 the preceding end of its major axis tilted northwards by the 

 mountains, while in Western Australia we see the first isobar of 

 the incoming high pressure, and over Perth the A depression 

 which divides the two. No. 7. The axis of the anticyclone is 



