112 WIND. 



Position i''.— Wind S.W. Winh the Cape Crozier Party was at F. on July 10 a)Kl 11, 

 1911, there was a blizzard at Cape Evans throughout which a high wind blew from the E.S.E. 

 and E. The wind experii^iced by the party was just as high and as steady but it was 

 from the S.W. and S.S.W. 



Position G. — Cape CVo'/er.^Wind S.S.W. As is well known the Cape Crozier Party ex- 

 perienced an e.Yceedingly violent blizzard on .July 22 and 23 while at Cape Crozier. 

 During the height of this blizzard the wind at Cape Crozier was S.S.W. while at Cape Evans 

 it was steadily from the E. 



Position H. — Corner Camp.~ln the autunni of 1911 a small wind vane was erected at 

 Corner Camp which was so arranged that a steel point comiected to the vane pressed on 

 to the aluminium ba.se plate, the idea being to deduce from the position of the maximum 

 scratching the direction of the prevailing wind. Wh.en Captain Scott saw this vane in 

 November, 1911, after it had been exposed throughout the winter he foimd that the maximum 

 scratching' indicated 'a predominance of wind from the S.W. quarter." 



Position I. — ^The winds at I and to the south are clearly indicated by the sastrugi which 

 all point to the high winds coming from the S. or S.S.W. 



From figure 37 it appears safe to conclude that during blizzards the wind streams along 

 the w^st of the Barrier parallel to the edge of the high land. When this southerly stream 

 impinges on Ross Island it breaks up into two branches one of which passes Cape Crozier 

 as a S.W. or S.S.W. wind, and the other enters McMurdo Sound as a S.E. wind. 



Thus the easterly components of the wind at Cape Evans and Hut Point are the result 

 of the air being compelled to move round the south-west shoulder of Erebus. During the 

 most violent blizzards there is a great crowding of the stream lines on to the slopes of 

 Erebus and then the wind becomes due E. at Cape Evans, while at Hut Point there is 

 a local ridge which still furt.her deflects the wind, and the wind which is E. at Cape 

 Evans becomes E.N.E. or even N.E. at Hut Point. 



The fact that a high easterly wind at Cape Evans occurs when there is a violent southerly 

 wind along the west of the Barrier, will be of great importance when we come to construct 

 isobaric charts. 



The conditions which give S. to S.W. winds over the Barrier are isobars running more 

 or less from south to north with the low pressure in the east ; when isobars are drawn in this 

 way on a small scale map it often appears as though the easterly wind at Cape Evans 

 is blowing from low to high pressure. 



We have now seen that the majority of winds at Cape Evans are the deflected winds 

 of the air stream which flows from the south during the blizzards. It is quite clear that 

 there can be no true winds blowing across the Sound for the Western Mountains on the 

 one side and Erebus on the other prevent such air motion. As seen from Cape Evans Mount 

 Erebus occupies the horizon from E. to N.N.E.. hence winds from the directions between 

 these points are practically impossible. The three directions E.N.E., N.E., and N.N.E. have 

 only "5 per cent, of wind frequency. The horizon becomes open from N. to N.W. and the 

 frequency of the winds from these directions increases, forming as we have already seen the 

 only winds of any importance beyond those fi'om the S. to E. quadrant — the three directions 

 N., N.N.W., and N.W. have 122 per cent. From the W.N.W., thougli W. to S. the hoiizon 

 is again closed by the Western Mountains and the six wind directions from W.N.W. to S. 

 have together only r4 per cent, of the total winds. 



Thus we see that the only motion possible in the McMurdo Sound is from the Ross 

 Sea to the Barrier and from the Barrier to the Ross Sea. From the position of Cape Evans 

 it happens that there are two directions which sharply divide off .the two kinds of air motion. 

 During nineteen months not a single wind from the W.S.W. was recorded, and from the 



