30 Mr. R. M. Deeley on the 



the authority is W. van Bemmelen*. The number of regis- 

 tering balloon ascents made in high latitudes is not sufficiently 

 great to enable us to ascertain the mean annual temperature 

 -of the stratosphere up to 20 kilometres. One such ascent at 

 Pavlovsk made in May 1905 showed an increase of tempe- 

 rature in passing from 11 to 17 kilometres of 10°*7 C. 



The point these vertical temperature gradient curves bring- 

 out clearly is that there are great temperature differences at 

 similar heights, in^both the stratosphere and troposphere, in 

 different latitudes; but these differences act in opposition 

 to each other. Unfortunately our knowledge of the general 

 temperature distribution in the stratosphere is not sufficiently 

 detailed to enable us to decide whether the increasing general 

 temperature of the stratosphere with increasing latitude is 

 sufficiently great to cause the lower winds of middle latitudes 

 to move polewards in spite of the adverse temperature gradient 

 of the troposphere. All that can be said as yet is that the 

 information as to temperature obtained by balloon ascents 

 shows that there is a strong temperature gradient in the 

 upper atmosphere acting in opposition to the surface tempe- 

 rature gradient. 



Shawf has maintained that the stratosphere has an im- 

 portant influence upon the winds. He propounded a problem 

 on this subject in a letter to * Nature''; but considered the 

 case of a horizontal lower stratosphere surface and regarded 

 insolation as resulting in the superior heating of the strato- 

 sphere over low latitudes. The conditions given in fig. 10, 

 however, show that the troposphere is thicker in low than in 

 high latitudes, and that the whole stratosphere has a higher 

 temperature in high than in low latitudes. 



What is required is further information concerning the 

 temperature of the stratosphere, so that we can compare the 

 temperatures over the equatorial belt with those over the two 

 high pressure belts at 30° N. and S. lat., and those over the 

 Arctic and Antarctic Circles. 



That the winds actually blow as though in middle and 

 high latitudes the stratosphere temperature gradient over- 

 powers the low level gradient, is shown by the fact that 

 balloons which reach the stratosphere — although the lower 

 wind may have a northerly moving component — generally 

 fall to the south and east of the starting point. 



It has been assumed that the cold upper temperatures at 

 the equator are due to the uprising of the air caused by the 



* Nature, March 5th, 1914, p. 6. 

 t Nature, June 11th, 1914, p. 375. 



