WINTER ASCENTS. 



273 



Winter Ascents. 



Table 133. 



Record I. 



August 13, 1911. 



Time 12-20. Erebus smoke from S. 



The previous day had been calm with a clear sky. The temperature had been slowly 

 falling for the previous forty hours from -27° to — 39" C. due to the clear sky and absence 

 of mild. At the time of ascent there was some (7) cirrus stratus cloud but no appreciable 

 wind. On ascending the balloon moved slowly towards the N.W. and then came back. The 

 instrument was found about 2| kilometres to the N.W. of the station. The temperature 

 increased from the gromid to 1,500 metres, the rise being just 5'^ giving a mean negative 

 gradient * of — ■33°C. per 100 metres. From this point the temperature fell slowly, the 

 decrease being at the same rate as the previous increase so that the temperature at 3,000 

 mstres was exactly the same as on the gromid. It is probable that the point of inversion 

 of the temperature corresponded with the change in the very slight air movement, the lower 

 cold layers slowly moving to the N.W. with the air above moving somewhat more slowly 

 in the opposite direction. 



■ Table 134. 



Record II. 

 August 16, 1911. 

 Time 10-55. Erebus smoke from N.W. 



* Throughout this work a negative sign prefixed to the gradient signifies that the normal temperature gradient 

 was reversed, so that the temperature rose with the lioight. 



35 



