2+ METEOROLOGY 



These blow usually from about W.N.W. to E.S.E. Again, as in the case of the 

 winds on the Barrier near Bax-ne Inlet and Mulock Inlet, they owe their origin to 

 the stemming action of the high portion of the Antarctic Horst known as the 

 Admiralty Range. As shown on Plate V., the horst, as one passes from Mount 

 Larsen (5000 feet), across the Reeves Glacier to Mount Nansen, jumps up suddenly in 

 level from 5000 to over 8000 feet. Cold air flowing down the southerly slopes of this 

 range overlooking the Reeves Glacier deflects the eastward-moving air masses 

 flowing down to Ross Sea. These plateau winds in winter time must be of hurricane 

 force, as they have torn out immense sastrugi in the hard snow of the Drygalski 

 Barrier. 



Along the belt of inland firnfeld marked " parting of the winds " on Plate VI. we 

 found loose powdery snow devoid of sastrugi. This was the highest j^oint on the 



_____^^ Top of the Plateau. 



The W.S.W. to N W 'x*/ Partingortne surface WmOs 



. Maonetir Pol*? Rv^a ^ ! ^— . 



IDO lot i^ t;Dt» ___ 



Magnetic Pole area 



Dense Snot^ C/oTIds 



Wilhes Ant'irvclonic strong St Winds 



Land? - -^ ■* •* •* * 



'r 



Hf. Wind 



?^"iS9* ^ ; / DenseSnow , C/ouds "S, 



< ■'' . - W/VW *•/.,. " TT.. \ 



Sea ne3' 



— Mii^d'ii^'S^^dU-e or PlateaZ ~~k^^^ 



fj^"' ^^LSlgtf'ao ',fSESsM' Nansen BOOOf 



^^^^^lateauRocKsrseenSSOStiyShackletonsEipedition) 





w^L7f^„n<jmm- inland snu» ^-^ ■-- - feeverGj^^&fCS Drygaish, 



'*^^ ROSS S£ 



y- >A Barrier 



/ Sea Lei-vl A — » 



^ — ' -* - — - - — — — — atouc ado miles -- — — — — — — ___.». ^ r** 



N.W. vertical Scale ■ lOOOO reeC io an Inch S. E^. 



Fig. 5. SECTION ACROSS THE SOUTH MAGNETIC POLE PLATEAU 



Showing tlie parting of the surface winds on the plateau, and the probable 



nature of the atmospheric circulation and snow supply 



plateau on our line of traverse. It was 7350 feet above sea level. From thence, for 

 80 miles, to our furthest point N.W. the winds completely changed In direction, and 

 blew chiefly In two directions forming two very definite and distinct types of 

 sastrugi. 



The wind blowing from S. by E., or S.S.E., was evidently the normal antlcyclonic 

 blizzard wind blowing with great violence and ripping up the surface of the hard snow 

 into sharp-edged sastrugi, three to four feet high. These were crossed by what we 

 call ramp* sastrugi, as, being flat-topped, they formed miniature Inclined planes, 

 placed at an oblique angle to the other sastrugi, and so enabling us to sledge over 

 what would otherwise have proved to be almost impassable snow ridges and 

 furrows, t 



The foregoing figure (5) Illustrates our view of the winds of the Magnetic Pole 

 Plateau and the part they play in supplying snow to the plateau. 



* Ramp in a fort is defined as a road cut obliquely into, or added to, the interior slope of the rampart. 



t These ramp sastrugi seemed to us to be formed by the blizzard winds, as they slackened ofl', always 

 hauling arouud to the east. As it swung around it gradually built these ramp sastrugi, which became flat- 

 topped owing to the progressive swing of the wind direction from south to south-east. 



