TURBIDITY AND TEMPERATURE GRADIENTS 



The relations between temperature and turbidity structures 

 may also be illustrated by their respective vertical gradients. 

 To show this, the data of each series were divided into 5 -hour 

 periods. For each period, the average turbidity and the 

 average temperature were computed for every 5 feet of depth. 

 Graphs were then constructed showing the average turbidity, 

 the average temperature, and the first derivative of each 

 with reference to depth for every 5-hour period. Figures 

 13 and 14 are examples of the variations of temperature and 

 transparency with depth from the data of 4 and 5 August 196 0. 



The vertical temperature gradients, dT/dZ, are always 

 negative in summer at the measurement site, which indicates 

 consistently colder water with depth. However, the vertical 

 transparency gradients, dTr/dZ, may be either positive or 

 negative. Positive values signify clearer water with depth. 

 In figure 13 the transparency shows nearly all positive 

 gradients with depth. The highest positive gradient occurs 

 at a level just below the level of the maximum thermocline. 

 In this case the level of maximum transparency (deepest 



Figure 13. Comparison of vertical temperature and 

 transparency gradients 1000-1430 on 4 August 1960 

 showing a positive maximum transparency gradient 

 below the thermocline. 



17 



