246 PRESSURE, WINDS AND WEATHER. 



Kerguelen and Snow Hill. — The records for these stations show both pressure waves and 

 cyclones, but the latter predominate at Kerguelen and the former at Snow Hill. 



The Bluff and Melbourne. — At these stations there is little if any evidence of 

 pressure waves, the barometer changes being almost entirely due to travelling cyclones and 

 anticyclones. 



From these results we are led to recognise long and deep pressure waves radiating out 

 from the Antarctic Continent and extending over the Southern Ocean to some unknown 

 distance from the continent, traces of which can still be seen in the pressure curves for 

 Kerguelen. Over the Southern Ocean there are cyclones and anticyclones which travel on the 

 whole from west to east. These systems are nothing like so large as those described by 

 Lockyer, but in all probability are in all parts of the ocean of a similar size to those shown 

 on the Australian Daily Weather Reports, and their centres may pass anywhere between the 

 coast of Australia and the coast of the Antarctic Continent. 



This result explains completely the results obtained in the statistical investigation of the 

 non-periodic pressure changes. The waves over the Antarctic are long, regular and deep as 

 can best be seen on the curves for Framheim. The barometer changes due to passing cyclones 

 over the Southern Ocean are deep but short. Hence as "we pass from the region of 

 cyclones over the ocean to the pressure waves over the continent the length of the waves 

 steadily increases, but there is little change in the amplitude, which is the conclusion already 

 reached on pag3 188 from the observations. 



Returning now to the theories of Lockyer and Meinardus with which we commenced 

 this discussion, we see that there is no evidence of the large cyclones having their centres 

 on 60° S. and covering the whole area from the south coast of Australia to the ice barrier 

 aromid the Antarctic, which are the chief features of Lockyer's work. We have also shown 

 that the pressure changes at the Gauss Station, Cape Adare and Hut Point used by Lockyer 

 in his discussion are not due to cyclones over the Southern Ocean and therefore give no 

 indications of the frequent y, intensity or rate of motion of such cyclones. Further we have 

 seen that the centres of small intense cyclones pass quite near to Cape Adare and we know 

 from the daily weather charts of Australia that the centres of cyclones often pass near to the 

 southern coast of that continent. It is therefore reasonable to suppose with Meinardus that 

 the centres of cyclones occur in all parts cf the Southern Ocean, but probably more frequently 

 near 60° S. than in any other latitude. Thus Lockyer's scheme of southern hemisphere air 

 circulation, simple as it is, does not fit the facts and must be abandoned. On the other 

 hand t^ere seems to be no justification for Meinardus's conclusion that the weather at the 

 Gauss Station is governed by these Southern Ocean cyclones, and not by the Antarctic anti- 

 cyclone. He admits that along the whole coast of the Antarctic Continent and for some 

 distance over the surrounding sea the mean isobars are concave towards the high pressure 

 in the south, but holds that the mean pressure distribution is not the governing factor in 

 the weather. The mean pressure distribution, he says, is the result of the sum of the 

 instantaneous pressure distributions and the latter are mainly due to the cyclones which pass 

 to the north of the station. Thus the weather at the Gauss Station in spite of the shape 

 of the mean isobars is not under the influence of the Antarctic anticyclone but mider the 

 influence of the cyclones which give rise to the easterly winds. Now we have shown that 

 the easterly winds at the Gauss Station and the pressure change there are not due to 

 cyclones, therefore the whole of Meinardus's scheme falls. In place of it we consider that the 

 Antarctic anticyclone extends outwards from the continent to some distance over the sea, 

 and that the pressure and wind changes are due to pressure waves radiating outwards from 



