TEMPERATURE OF THE HYDROSPHERE 193 



thermal conditions at — 1.2° to — 1.3° C. exist. In the Central 

 Polar Sea, the temperatures of the upper strata (themselves of a 

 dichothermic arrangement) are mostly below — 1° C. and range 

 from 160 m. to 200 m. in depth, where the temperatures sometimes 

 are as high as — 0.2°. A second stratum of mesothermal character 

 ranges from -j-o.2° to +1.2° and lies between 200 and 800 meters 

 in depth, while a third deeper, nearly homothermal, one of — 0.7° 

 to — 0.8° extends to depths of 3,000 and 3,800 meters, though the 

 actual temperature of — 0.7° is not reached above 1,400 to 2,000 

 meters depth. Of the other dependencies of the Arctic Ocean the 

 shallow White Sea has winter temperatures of — 1.9° to — 1.6°, 

 which range throughout and are associated with a salinity of 34.85 

 permille and 30.08 permille, respectively. In the summer months 

 the temperature rises to over -|-I3° on the surface, but below 30 m. 

 the temperature is under 0°, while below 120 m. it is — 1.6°, as in 

 winter. This does not hold for the very shallow^ bays, however, 

 where temperatures of 8° to 9° and over are still found at the bot- 

 tom of 30 to 35 meters. 



Mean Temperatures of the Oceans and Intracontinental 

 Seas. The mean temperatures of the four oceans have been de- 

 termined to be as follows (Kriimmel-20 :-/p5), see, ante, p. 146: 

 Arctic, —0.66° ; Pacific, +3.73° ; Indian, +3.82° ; Atlantic, +4.02° ; 

 mean of three larger oceans, -|-3.86°. This shows that, taken as a 

 whole, the Atlantic is warmer than the other oceans, this being due 

 to the comparatively high bottom temperatures. As already noted, 

 when surface temperatures alone are considered those of the Pacific 

 are higher than those of the other oceans. Of the mediterraneans, 

 the Red Sea has the highest (22.69°) ^"^ the Japanese the lowest 

 (0.90°) mean temperature. In the latter only the surface waters 

 down to 100 or 150 m. are warm, the western side being cooler 

 owing to the cold southward-flowing current. The deeper waters 

 of the central basin have a temperature of 0.7° to 0.3°. Among the 

 epicontinental seas the Persian Gulf has, as might be expected from 

 its location, the highest mean temperature (24°), while Hudson Bay 

 has the lowest (1.0°). 



Eutectic Temperatures. This term is applied to the tempera- 

 ture at which salts are separated from cooling waters holding them 

 in solution by the simultaneous crystallization of the salt and water. 

 This temperature is always lower than the temperature of freezing 

 water, and difi^ers for the different salts in the following order, as 

 shown by Pettersson {2j:^ot, see also Krummel-20: 50?) ; NaoSO^ 

 (— o.7°);KCl (-ii.i");NaCl (-21.9°) ; MgCU (-33.6°) ; CaCL 

 ( — 55°). With progressive cooling the salts would thus be sep- 



