TEMPERATURE 81 



them towards the eastern coasts of the con- 

 tinents. 



The North and South Atlantic are in striking 

 contrast at this depth, the North Atlantic 

 being much warmer than the South Atlantic. 

 In the South Atlantic the area with a tem- 

 perature above the mean for this depth is 

 small as compared with the similar area in 

 the North Atlantic, and the highest tempera- 

 ture in the South Atlantic is only 63° F., 

 whereas in the North Atlantic there is a large 

 area with a temperature exceeding 63° F., 

 which encloses two small areas each with a 

 temperature rising to 70° F. This contrast is 

 due to the fact that in the Atlantic the region 

 of calms between the north and south trades is 

 at all seasons north of the equator, reaching 

 its northern limit in lat. 13° N. in July, aiid 

 its southern limit in lat. 2° N. in January. 

 Hence the south-east trades penetrate at all 

 seasons into the northern hemisphere, driving 

 before them the warm surface waters of the 

 South Atlantic. Thus vast quantities of 

 warm surface water are transferred bodily 

 to the North Atlantic, resulting in these two 

 ocean basins presenting as regards tempera- 

 ture the strongest contrasts to each other, 

 not only at 100 fathoms but at all depths 

 down to the bottom. The mean annual 

 position of the region of equatorial calms 



