THE HEART OF THE ANTARCTIC 



thirty hours, the temperature would have risen to plus 12° 

 or plus 15° Fahr. 



This rise in temperature may have been due to causes 

 of which the more important are: First, the usual fohn 

 effect, the temperature of the air being raised through 

 compression as the air descends from higher levels to 

 lower. This compression effect ought theoretically to 

 make itself strongly felt at the atmospheric South Polar 

 vortex. Secondly, the latent heat set free when aqueous 

 vapour in the atmosphere is passing into the form of snow 

 which, of course, tends to raise the atmospheric tempera- 

 ture. It might also be suggested that as the atmospheric 

 circulation during a blizzard is immensely accelerated, 

 probably the upper winds under these conditions may 

 transfer relatively warm air from tropical regions pole- 

 wards. If this be so, it is quite possible that some of the 

 snow which falls towards the close of a blizzard was formed 

 out of the moisture generated in warmer climates. 



The Southern Party specially studied the question of 

 whether much snow fell far south, and the Northern 

 Party, who went to the South Magnetic Pole, also paid 

 special attention to this point of whether the snowfall 

 increased in proportion as one receded from the South 

 Pole. As the result of the observations of the Southern 

 Party it was clear that within ninety-seven geographical 

 miles of the South Pole there were still very strong south- 

 south-east winds, bringing with them a quantity of snow. 

 During the time the Southern Party were on the plateau 

 no falls of fresh snow were observed; but there was 

 nothing to suggest that the annual snowfall was less than 

 at winter quarters. 



Temperature. — ^The lowest temperature we ex- 

 perienced was minus 57° Fahr., near White Island on the 

 Great Ice Barrier, on August 14, 1908. We may refer to 



404 



