SECT. 2] LARGE-SCALE INTERACTIONS 251 



consistent with the density of the air column above them. If the lapse rate is 

 essentially wet adiabatic, we saw that the pressure fall was linearly related to 

 the increased heat content of the rising air, or 



where y^lS mb per cal/g. 

 Furthermore, 



^ = U^^=Qsp + Qep. (69) 



Combining (69) and (68) and substituting from (62), we have 



--^ = ^-{Qsp+Qep) ='^[ksp{To-Ta) + kep{eo-ea)]. (70) 



p OS U p p 



To be consistent with (67), 



hp{To-Ta) = '^[ksp{To-Ta) + kep{eo-ea)] (71) 



P 



or 



-AQsp = Qep, (71a) 



and a relation between sensible and latent heat pick-up, or the Bowen ratio, is 

 prescribed. When y is placed in proper units, y/p;i;0.26 and Qsp = 0.35Qep, in 

 excellent agreement with the results of Table XXI. We see that not only must 

 exchanges be augmented to maintain a hurricane but also the enhanced Bowen 

 ratio is an essential feature of its machinery! This precision engine requires 

 many finely fitted parts to operate, and as we look at it more closely its rarity 

 in nature becomes less surprising. 



The foregoing analysis suggested an inverted approach to the hurricane 

 problem. Rather than asking what exchange is required to maintain an observa- 

 tionally realistic dynamic situation, as previously, we now reframe the question: 

 Let the product ksp{TQ-Ta) be fixed, and let this prescription choose between 

 the dynamically possible solutions to (57), using the relative stabihty criterion 

 of W. V. R. Malkus and Veronis (1958). This was done by integrating (65) 

 vertically through the inflow layer, and substituting (17) for to so that the 

 kinetic energy equation becomes 



dK U 8p CD ^ ,r.tr s 



-_ = — ^- u^ (65a) 



at p OS bz 



or has the form, using (40a) and (61), 



^ = Au-Bu\ (65b) 



at 



