Figure 4. Two intersecting trains of internal 



THERMAL STRUCTURES 



Temperature changes at either the surface or various depths 

 may be caused by several factors, such as (1) the advection of 

 water of a different temperature; (2) radiation from the sun; (3) 

 mixing by the wind; (4) tidal currents; or (5) internal waves. 13 

 Since such forces may occur simultaneously, it is difficult to de- 

 termine their individual effects, but a detailed, two-dimensional 

 data section, obtained by the thermistor chain, can frequently in- 

 dicate the contribution of each factor to the processes taking place 

 in the sea. 



The thermal structure presented here is more properly the 

 "structure of encounter" or "depth of encounter of isotherms. " 

 The vertical scale is depth, but the horizontal scale may be con- 

 sidered as either time or distance. The amplitude of the vertical 



