278 



UPPER AIR OBSERVATIONS. 



Table 140. 



Record VI. 



November 15, 1911. 



Time 10-30. A cumulus cloud iiKivini; from N. 10'' K. 



The weather conditions during this ascent were very similar to those during the previous 

 one. The ascent was made during a few calm hours between two blizzards. As before, the 

 temperature had been fairly steady until the calm weather set in when it commenced to rise. 

 The sky was 8/lOths overcast with alto-stratus and alto-cumulus clouds. The balloon moved very 

 slowly towards the S.E. and did not appear to change its direction ; evidently the current 

 of air which was moving the clouds from N. 10° E. extended to the ground with only a 

 small change of direction. 



The gradient in the fii-st 500 metres was smaller than in the previous record, being -42° and 

 •78" C. par 100 mstres respectively. Above 1,000 metres the gradient became much smaller, 

 and between 1,500 and 2,000 metres it was only •36°C. per 100 metres. This reduced gradient 

 obviously belonged only to a layer, for at 2,000 metres the rate of fall of temperature again 

 increased, and from 2,000 to 3,000 metres the mean gradient was •72°C. per 100 metres. 



The characteristics of the vertical temperature distribution during this ascent were as before — 

 a region in which the gradient was considerably smaller than in the regions above and below. 



Record VII a, h cmd c. 

 November 19, 1911. 



The three balloon ascents made on this day are very interesting. For the first time 

 balloons without silk thread were used, the ascent of the large balloon and the descent of the 

 instrument with the small marking balloon attached being followed through a theodolite. 



At 11-30 the first balloon was sent up. The fuse used for liberating the instrument 

 was timed to burn through in fifteen minutes. The balloon rose ahnost vertically, and a few 

 minutes before the instrument should have been detached, it was right overhead. In this 

 position a small motion of the balloon required a very large motion of the theodohte in 

 azimuth to keep it in the field of view, and it was found impossible to make this rapid 

 motion and the balloon was lost to sight. After waiting until the instrument was estimated 

 to have had time to fall, the theodohte was used to scan the surrounding ice floe to see 

 if the red balloon attached to the instmment was in sight. No trace of it could, however, 

 be seen, and the instrument was given up for lost, when it was seen to fall less than one 

 hundred metres away. The fuse had evidently burnt longer than was expected, and when 

 the record was worked out it was foimd that it had been up nearly 4,000 metres. That 

 after sucb an ascent the instrument should fall so near to the starting point showed that the 

 lower atmosphere was remarkably calm, and I at once determined to make a more serious 

 attempt to get a high ascent. 



