NO. 17.] 



TEMPERATURE OF THE AIR. 



497 



SSE 28' 9. The diurnal variation of the temperature is in perfect accord- 

 ance with the diurnal change of the direction of the wind in the dark season. 



In the crow's nest of the Fram, 32 metres above sea-level, observations 

 of the temperature of the air were taken simultaneously with the temperature 

 in the thermometer-screen below. These are given in the following Table. 

 The observations were made about noon. The Table shows the difference 

 between the temperature at the height of the crow's nest and that in the screen, 

 the wind's direction and velocity in metres per second, and the amount of 

 cloud at the same time. 



The observations made in the crow's nest are perhaps not so reliable as 

 those made in the screen; and the result of their comparison is scarcely 

 capable of being utilised for a correct determination of the variation of the 

 temperature with altitude. Meanwhile the great excess of negative differences 

 tends to show that in the colder months an inversion of temperature is a 

 phenomenon of very common occurrence. 



63 



