526 



Internal Waves 



ternal waves of long wave length. On anchor station 254 of the "Meteor" 

 expedition (31 January to 2 February 1927, <p = 2°26-7'S., I = 34°57-4'W., 

 average depth h = 3910 m) 23 series were lowered down to a depth of 200 m 

 with an interval of approximately 2 h (see Defant, 1932, p. 164). These 

 observations give the average vertical distribution of temperature, salinity 

 and the density a t as shown in Fig. 215. It shows that in an average depth 

 of 100 m there was a pronounced discontinuity in the vertical density dis- 

 tribution, which almost had the nature of a discontinuity surface. The nearly 



17 

 16 

 6 

 14 



» 



13 



25 



16 20 4 8 12 

 111-27 



Time of zone, nr 



16 20 4 

 211 27 



Fig. 216. Temperature variations in different depths at "Meteor" Anchor Station 254. 



homogenous top layer had a density of a' t = 23-6 and a thickness of ap- 

 proximately 100 m, the lower layer had a density o t of about 26-7 and its 

 depth was very large in proportion to the thickness of the upper layer. The 

 velocity of progress of long internal waves, in this case, according to the 

 equation XVI. 14, is c 2 = 172 cm/sec. 



