54 



TEMPERATURE. 



From figure 20 it wll be seen that the observations are not sufficient to give smooth 

 curves, especially in the winter months, when the daily amplitude is small and non-periodic 

 changes large. 



Fig. 20. Daily variation of temperature. McMurdo Sound and I'ram Drift. 



The sun returns after the winter on August 21, so that September is the first month 

 of the year in which the sun is above the horizon every day. The days lengthen at a rapid 

 rate, and on October 26 the sun does not set again until February 17, after which the 

 days shorten rapidly until on April 24 the sun rises for the last time. 



September to March — Period with direct Solar Radiation. 



From September to March the daily variation of temperature is well marked and ia 

 obvioiusly the result of the daily variations in the intensity of solar radiation. 



