^6 THE OCEAN 



North Atlantic eastward of Nova Scotia, and 

 the highest reading in the open ocean is 90° F. 

 recorded in the tropical Pacific both north 

 and south of the equator, while readings of 

 94° and 96° F. have been recorded in the 

 Red Sea and Persian Gulf respectively. The 

 greatest known range of temperature in the 

 surface waters throughout the whole world is 

 thus 70° F. (from 26° to 96°), being very small 

 when compared with the extreme variation of 

 the temperature over the land-surfaces of the 

 globe, which may exceed 220° F. 



Temperature Conditions beneath the Surface, 

 — ^Let us now turn to the distribution of tem- 

 perature in the depths of the ocean. Except 

 in the icy regions of the far north and far 

 south, and in some other exceptional positions, 

 the temperature of ocean water decreases 

 from the surface downwards to the bottom. 

 In tropical regions, where the water at the 

 surface is warm (75° or 80° F.), the tem- 

 perature decreases at first very rapidly, the 

 warm water forming a relatively thin film, 

 then more and more slowly towards the bottom 

 in deep water. This is the general rule as to 

 the distribution of temperature in the open 

 ocean, but an exception is found in the case of 

 partially enclosed seas, like those fringing the 

 western border of the Pacific Ocean, which are 

 cut off from the general oceanic circulation by 



