70 



DEACON AND WEBB 



[chap. 3 



deviation is particularly marked on the lapse side, Ta—Ts< 0. Referring back 

 to the lower-level observations in Fig. 12, the corresponding deviation on the 

 lapse side is in fact discernable in the lightest winds. 



The slope of the straight line fitted in Fig. 12 indicates a value of Fh at a 

 height of 4 m as 0.10 with no evident dependence on wind strength; and the 

 same relationship converted to the co-ordinate scales in Fig, 13 is seen to be 



-4 -3 -2 



Potential temperature, deg F 



(q) .1 .2 .3 .4 



Potential temperature, deg F 



-2.6 -2,5 -2.4 -2.3 (b) 

 Potential temperature, deg F 



LAPSE 



.2.5 »3 .3.5 

 Potential temperature, deg F 



INVERSION 



Fig. 11. Specimen profiles of potential temperature plotted against : (a) linear height scale, 

 and (b) logarithmic height scale. 



Lapse: observation No. 134 (10 min), November, 1956, in Bass Strait, 

 wi3 =- 5.8 m/sec, Rh^ = - 0.08. 

 Inversion: observation No. 48 (15 min), May, 1958, in Port Phillip Bay, 

 wi3 = 7.3 m/sec, Rb^ = -t-0.13. 



also consistent with the measurements plotted there, apart from the deviations 

 produced by thermal stratification. Values of Fh quoted by Sheppard (1958) 

 from earlier published observations are in broad agreement with the value 

 indicated above, while Brocks (1956) has measured temperature gradients by 

 an optical refractive index method, and these indicate a value of Fh virtually 

 identical with it. 



