160 CLOUD AND PRECIPITATION. 



Windvane Hill — and the roof of this cave became so thin that towards the end of the summer 

 ot 19 12 I began to have serious doubts as to its safety. Thus from January, 1911, to the 

 end of February, 1912, there was a marked diminution in the snow and ice accumulations on 

 the Cape. 



When the sea froze in March, 1911, a tb.in deposit of snow accumulated on the sea ice 

 to a depth of one or two inches, this never increased all through the winter and when in 

 September we made a sledge journey across the Sound the only places where we could find 

 sufhcient snow for erecting the tent were the drifts in the lee of broken ice. The blizzard 

 at the end of September (2.5th to 28th) left large drifts about the hut and hills, but no 

 accumulation of snow on the sea ice. During October and November there was a great loss 

 of snow. The drifts near to the hut diminished and all the snow disappeared from large 

 tracts of the sea ice. From Cape Evans to Cape Barne on November 29, 1911, the floe was 

 entirely clear of snow exposing the smooth blue sea ice. 



Thus in the neighbourhood of Cape Evans the total snowfall for eleven months had 

 produced no addition to the snow accumulations, but on the contrary the permanent snow- 

 drifts had become visibly smaller. 



On Decomber 6, 1911, the first heavy snowfall unaccompanied by high wind was ex. 

 perienced. This left 18 inches of snow on the floe which, in consequence of a high northerly 

 wind on the 8th, settled down to a depth of about i inches over all the frozen sea in our 

 neighbourhood. At the end of this snow-storm the accumulation of snow about the hut 

 was the greatest we had experienced ; large drifts covered most of the stores around the 

 camp, and large tracts of the hill which had always been clear before were now buried under 

 snow. From this time on successive blizzards added to the accumulation and 1912 was just 

 as marked for the increase of snow as 1911 had been for its disappearance. 



Onlv during the summer months was there anjiihing equivalent to the snowfall with which 

 we are familiar in temperate regions. The snow fell on December 6 in ordinary flakes, 

 but at other times of the year flakes were never observed. The snow was chiefly in the 

 form of small grains showing little crystalline structure, but occasionally crystal stars would 

 fall. In the absence of wind the snowfall was always light, and from March to October 

 the around never received more than a mere sprinkling of snow in the absence of blizzards. 

 Durin" blizzards the air became filled wtli snow literally in the form of dust. It was then 

 practicaDy impossible to say whether new snow wa,s falling or whether the whole mass of 

 snow in the air was simply fallen snow carried along by the wind. 



In the meteorological log we have three kinds of entries referring to snow and drift. 

 First the meteorological symbol for snow is entered, to which is almost always attached the 

 remark ' slight snow ' or ' very little snow falling.' Secondly, the two symbols for snow and 

 drift are entered together, but very frequently the sign for snow is queried, or the remark 

 is added ' probably snow,' thus showing the great difficulty of deciding whether new snow 

 was fallin" or not. Finally, there is the symbol for drift alone, and to this the remark 

 ' surface drift ' is sometimes added. In the latter case, there would certainly be no new snow 

 fallinc, but it is impossible to say how often the symbol for drift refers to drift with and 

 without snow, hence the records of drift include drift with and without snowfall. 



From March, 1911, to October, 1912, observations were taken every four hours and the 

 number of time the symbols for snow, snow with drift and drift were recorded have been 

 counted. In the follo\ving table these have been expressed for each month reduced to one 

 hundred observations. The numbers therefore in the table give for each numth the average 

 frequency with which each sign was recorded in one hundred hours. 



