THE WEDDELL QUADRANT AND ADJACENT AREAS. 117 



showing the conditions over the continent for the whole period of recent Antarctic 

 research. In this connection the South American data will be joined up with that 

 furnished by the Falklands and South Georgia. 



Mean Atmospheric Pressure Temperature and Cloud for the Year. 



The maps showing the mean annual barometric pressure, mean temperature, and 

 mean amount of cloud may be said to represent the sum and substance of the 

 year's weather (see figs. 1, 2, and 3, Plate IV.). 



The isobaric charts indicate in the clearest manner the relatively higher pressure 

 which prevails to the south over the Bellingshausen Sea, as compared with that over 

 the Weddell Sea in similar latitudes, and the wind-circulation follows the pressure- 

 distribution. The Peninsula of Graham's Land thus divides two wind systems. To 

 the west we have, as at Wandel Island, a marked prevalence of strong north-easterly 

 winds, due, as we have seen, to the all but permanent cyclonic area to the westward. 

 To the south of this is the region embraced by the " Belgica's " drift, in which the wind- 

 circulation is of a distinctly monsoonal character — easterly in summer, and westerly in 

 winter. Here the easterly winds are by far the strongest, indicating the steepness of 

 the barometric gradient between the Polar anticyclone and the South Pacific low- 

 pressure area. The anticyclone migrates with the season — facing the Pacific Ocean in 

 summer, and retreating over the continent to the south of the Indian Ocean in winter. 

 While these conditions represent the normal state, different seasons appear to diverge 

 considerably from the average. Thus in 1903 the Weddell Sea "low pressure" was 

 deepened, and lay further to the west than usual. As pressure was about the normal 

 north of 50° S., a very steep gradient was set up for W.N. W. and N.W. winds. That 

 this rapid fall of pressure prevailed to at least 65° S. is shown from Nordenskjold's 

 Snow Hill observations. In 1904, on the contrary, the pressure gradient was less than 

 half that of the previous year, as shown by the simultaneous observations at the 

 Falkland Islands and the South Orkneys. Between these two stations the mean 

 difference in the barometric pressure for the nine months April to December was 

 0'456 in 1903, while in the corresponding period of 1904 the difference was only 

 0'199 inch. The remarkable persistence of easterly winds during the winter of 

 1902 at the winter quarters of the Gauss in 90° E. indicates that the Antarctic 

 anticyclone lay over the frozen continent to the south and south-west of this 

 station (see footnote, p. 111). 



Pending the publication of the detailed official reports of the expeditions which have 

 taken part in the recent International Antarctic campaign, it would be premature to 

 draw final conclusions, but a careful analysis of all the available material enables us to 

 recognise four regions characterised by permanent low-pressure areas. These are 

 central in the Ross Sea in lat. 70° S., and long. 170° W. ; in the Bellingshausen Sea 

 in 65° S. and 90° W. ; in the Weddell Sea in 66° S. and 30° to 35° W. ; and in the 

 Antarctic Ocean in 63° S., between the meridians of 80° and 105° E. It will be seen 



