40 



TEMPERATURE. 



During December, as we have already pointed out, the temperature over the Barrier 

 is practically uniform, the temperature over the south of the Barrier being the same as 

 the mean iemperature at Cape Evans and Framheim. It seenis reasonable to assume that 

 if the Barrier had extended right up to the Pole the temperature there would have been 

 the same as that over the rest of the Barrier, viz., 21°F. The redured plateau temperature 

 is however only 17-3°F., which indicates that during December the plateau is between 2 

 and 3°F. colder than its geographical position wariants. During January we have not 

 sufficient observations from the south of the Barrier to determine the change of temperature 

 with latitude on the Barrier. Plateau observations are however available for the whole of the 

 month. From table 15 we see that during January the reduced plateau temperature was 

 10-3°F. lower than the mean of Cape Evans and Framheim. How much of this difference 

 h due to change of latitude it is impossible to say, but if it were all due to latitude it 

 would indicate a fall of temperature at the rate of rO°F. per degree of latitude. This 

 amount seems impossibly large for this time of the year, therefore it is almost certain that 

 the low relative temperature on the plateau both in December and January is not due to 

 its geographical po.sition, but is mainly due to its high elevation. 



From this discussion it ajjpears clear 



(a) that the temperature on the plateau is lower than its geographical position warrants ; 



(b) that this relative deficiency of temperature is greater in January than in December ; 



(c) that the observations made on the plateau cannot tlierefore be used in determining 



the change of temperature with change of latitude. 



It is instructive to compare the reduced plateau temperatures with the sea-level tem- 

 peratures at the corresponding latitude and time in the northern hemisphere. According to 

 Mohn's * determinations the mean temperatures at 88° N. during June and July are 28'6°F. 

 and 311°F. respectively. Thus we have 



Table 16. 



North and South Polar Temperatures. 



Thus during the midsummer month the temperature in the neighbourhood of the South 

 Pole, when reduced to sea-level at the rate of ■5°C. per 100 metres, is 11-3°F. (6-3''C.) 

 lower than the corresponding temperature in the neighbourhood of the North Pole. The 

 difference is still greater in the next month, for whereas in the north the temperature con- 

 tinues to rise for a month after the solstice it commences to fall in the .south immediately 

 after midsummer day.f In consequence the temperature is 23-7°F. (13-2°C.) lower in 

 January near the South Pole than near the North Pole in July. 



We have so far considered only the plateau temperatures after they have been reduced 

 to sea-level, but it is of considerable interest to know the actual temperatures which were 



* The Norwegian North Polar Expedition, 1893-1890, Vol. VI, Meteorology, by H. Mohn, page 575. 

 •f See page 88. 



