TEMPERATURE 69 



(over 80° F.) lie to the north of the equator, 

 owing to the fact that in these parts of the 

 ocean the south-east trades protrude north of 

 the equator as the simple result of the geo- 

 graphical distribution of atmospheric pressure 

 there. Very different is it in the western 

 division of the Pacific, where an area of high 

 surface temperature (over 80°) extends east 

 of Australia as far south as lat. 20° S., due 

 to the circumstance that for eight months of 

 the year the line of lowest barometric pressure 

 is there to the south of the equator, and neces- 

 sarily accompanied by northerly winds which 

 propel into more southern regions the warmer 

 surface waters of the western Pacific. 



In the Indian Ocean a comparatively low 

 surface temperature prevails over the north- 

 western portion of the Arabian Sea, brought 

 about by the prevailing north-westerly winds 

 driving the warm surface water to the south- 

 eastwards, and thus by upwelling off Cape 

 Guardafui bringing the colder waters of lower 

 depths to the surface. On the other hand, 

 the prevailing winds in summer at the head 

 of the Bay of Bengal are southerly and south- 

 easterly, bringing from tropical regions the 

 warm waters of the surface over the whole 

 of the northern portion of this sea. 



In the eastern part of the North Atlantic 

 the prevailing southerly and south-westerly 



