DESCRIPTION OF THE ISLANDS 34S 



as a rule is far removed. For the rest of the year — from late autumn throughout 

 winter to spring — the South Orkneys generally become involved in a sheet of pack-ice 

 of continental magnitude and exhibit the climatic extremes characteristic of a con- 

 tinental station. 



In a broad sense, then, it is true that for a period of seven or eight months (from 

 about April to November) the South Orkneys are subject to continental climatic con- 

 ditions, while it is only for four or five months of the year (from about November to 

 March) that they possess a climate typical of their oceanic situation. The matter 

 cannot however be stated so simply as this, largely owing to the uncertainty 

 both as to time and place of the major movements of the pack-ice in the neigh- 

 bourhood of the group. In the first place, the period during which the islands remain 

 firmly enveloped in the frozen sea does not fall within definite time limits, with the 

 result that the continental character of the climate is sometimes emphasized at the ex- 

 pense of the oceanic, and vice versa. For instance in 1908, according to Mossman, the 

 South Orkneys were surrounded by open sea practically throughout the year. No pack- 

 ice was seen in their neighbourhood, and indeed no sea-ice of any description except 

 during fifty-two days in July and August, when a level plain of young ice formed over 

 the sea as the temperature fell. As a result of this abnormally open year temperatures 

 were generally high, the climate being largely oceanic for the greater part of the year. 

 Secondly, the degree of the envelopment itself may vary considerably, or in other words 

 the northern edge of the frozen sea, instead of lying as it sometimes does a hundred or 

 more miles north of the islands, may on occasion lie much farther to the south in close 

 proximity to the islands themselves. When the winter ice-edge lies thus far to the south 

 a further climatic complication is introduced, for in the region where a frozen meets an 

 unfrozen sea a "theatre of cyclonic activity" is created where great variations of tem- 

 perature and weather prevail according as depressions pass to the north or south of the 

 observer. It is " an area of much cloud, strong winds, and considerable precipitation". 

 Unsteady winter conditions such as these, although on the whole uncommon, were 

 experienced by Mossman during the first of the two winters, 1903 and 1904, which he 

 spent at Scotia Bay. They aff'ord a striking contrast to the far steadier conditions which 

 prevailed during the second winter when the islands were well and truly enveloped 

 in a frozen sea. "In 1903" he writes "there was open sea in close proximity to 

 these islands, and the resulting weather was tempestuous, relatively mild, cloudy and 

 variable to a degree; but in 1904 the pack extended some 200 miles to the north, and 

 the weather was quite cold and in general clear, with a high barometer." 



In spite of their oceanic position and comparatively low latitude the climate of the 

 South Orkneys is cold. They are situated in the path of one of the major Antarctic cur- 

 rent systems, the Weddell Sea drift, which passing clockwise round the Weddell Sea 

 approaches the group from the south-west, carrying with it ice-cold water, sometimes 

 pack-ice, and generally large numbers of bergs. With this cold stream constantly flowing 

 past the group the temperature even in summer seldom rises more than 5 or 10° F. 

 above freezing. The mean annual temperature is 24° F., mean summer 32" F., and mean 



