THE CASPIAN SEA 



547 



Fig. 260. Diagrammatic distribution of surface temperatures 

 of the Caspian Sea in (A) February and (B) August. 



July and the beginning of August. At a depth of 50 m the highest temperature 

 was reached by the end of August, at that of 100 m in January, while deeper 

 still the greatest rise of temperature was in February ; that is, with a delay of 

 six months. At a time when it is winter on the surface of the Sea, at a 

 depth of 300 to 400 m there is a ' hydrological summer'. Below 400 m the 

 temperature remains constant. As an example the average annual data may 

 be given (Table 225); these allow a comparison to be made of the vertical 



Table 225 



