284 



UPPER AIR OBSERVATIONS. 



In the following tabic the gradient measured in each ascent is shown :- 



Table 148. 

 Mean gradient during the summer. °G. per 100 metres. 



By combining the results in this way the region of least gradient appears to be between 

 2,500 and 4,000 metres, but this is due to the irregularity in the number of ascents which 

 reached higher than 2,500 metres. 



Taking the mean temperature on the ground at the times of the ascents and applying 

 the mean gradients as shown in the above table we get the following as the mean state of 

 the atmosphere during the summer months as shown by these few ascents : — ■ 



Table 149. 

 Mean vertical temperatures during six days in the summer. 



These numbers have been plotted in figure 85. 



Summary of Summer Conditions, 



(a) The mean gradient from the ground to 2,500 metres is approximately •eS'C. per 

 100 metres, but individual ascents showed gradients of between '8° and '9° in parts of this 

 region. 



