109° 45' W. 



09°30 W. 



23°00 N. 



22°45'n. 



23 00 N. 



22 45 N. 



1 9 ° 4 5 ' W. 



I09°30 W 



Figure 14. — Tracks of three BT passes made at front 5 on 20-21 April 1961. The third pass (—•—•—) is the one discussed 

 in the text because it covers the greatest range of surface temperature, the isotherm contours of which are shown 

 ( .°C.). 



21 



