256 GENERAL AIR CIRCULATION. 



winds shown * do fit in fairly well with a low pressure area somewhere near where it has 

 been drawn in the diagram. 



Meinardus's reasoning and conclusions may be summed up as follows : — • 



As there is an excess of precipitation over evaporation in the Antarctic, as revealed by 

 the outward flow of great ice masses, the conditions cannot be anticyclone. 



There is certainly an anticyclone over the Antarctic at sea-level, but a calculation shows 

 that at 2,000 metre altitude this has already given place to a large cyclone which is more 

 or less central about the South Pole. 



Other calculations indicate that the avi?rage height of the Antarctic Continent is 2,000 

 metres or more, hence the smface of the high land is -svithin the region of the cyclone. 

 Thus the surface over the greater part of the Antarctic is subject to cyclonic conditions 

 with the associated excess of precipitation over evaporation. 



Thus the theories of Hobbs and Meinardus are totally opposed, the latter deducing that 

 the greater p.irt of the Antarctic is subject to a cyclonic pressure distribution while the 

 former declares that over the whole Antarctic there is a strong anticyclone. In spite of the 

 repetition entailed we must set out clearly the crucial points on which each theory is 

 based. 



Hobbs' paper practically reduces to proving that whenever observations have been made 

 in the Antarctic, both at ssa-level and on the plateau, the sm-face winds blow outwards 

 from the centre ; this is only possible if the air descends from above in a central calm area 

 and flows outward under an anticyclonic distribution of pressure. To this Meinardus objects 

 that in such a pressure distribution and air circulation the large precipitation necessary to 

 feed the huge glaciers and produce the constant supply of icebergs is quite impossible. 



On the other hand Meinardus deduces from the few observations of pressure and tem- 

 perature available a probable distribution of these two elements at sea-level over the whole 

 Antarctic. With these values he calculates the pressm-e distribution in the upper air and 

 shows that at 2,000 metres it becomes cyclonic. As the mean height of the continent is 

 probably more than 2,000 metres, its surface is under the influence of this cyclone in which 

 unlimited precipitation is possible. Hobbs' criticism of this theory is hardly worthy of its 

 importance, he shortly states it and then dismisses it in the following curt paragraph. 



' Referring to the observations by Captain Scott and others upon the plateau back of the 

 Admiralty Range in South Victoria I-and, Meinardus is cjiiick to seize upon the westerly winds 

 which there prevail as evidence that the anticyclone has at these levels given place to the 

 supposed overlying cyclone ; failing utterly to note that the winds are here blo\ving 

 directly down slope from the ice plateau — that is, radially, other statements in the report 

 are Ukewiss strikingly at variance with facts either known at the time or revealed by later 

 exploration. 'f 



When two eminent scientists, each of whom knows what he is talking about, come to 

 such diametrically opposite conclusions on the same evidence it is generally safe to conclude 

 that both have some of the truth and neither all the truth. We will therefore now examine 

 the whole question anew and seek a solution, which I believe is not very deeply hidden. 



* On page 264 below it wUl be shown that strong objection can be taken to some of the \iincl directiona 

 shown by Memardus in this diagram. When these are corrected the pressure distribution must be radically changed 

 to fit them. 



f Loc. cii; page 212. 



