78 DISCUSSION 
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Discussion 
Mr. Jerome Namias—If the ultimate aim in 
all this is to predict in detail, at what point there 
may have to be a cut-off in this prediction scheme. 
It would have to make inferences about condi- 
tions responsible for run-away processes and 
various things down to some scale. That is, must 
we settle for a certain scale? I'd like to ask Dr. 
Smagorinsky if he believes there is no cut-off 
point and if he expects to go to the bitter end 
and attempt to predict weather on all scales by 
numerical process. 
Dr. Joseph Smagorinsky—I would say that one 
can reasonably place a cut-off at the point where 
the statistical dynamics of the smaller scale mo- 
tions are sufficiently stable and well understood. 
The ability to establish a threshold of turbulence 
permits the study of the explicit dynamics of the 
synoptic scale motion with adequate provision for 
the interaction with the scales of motion ulti- 
mately responsible for the dissipation of kinetic 
energy. Such a threshold of the horizontal scale 
appears to be of the order of 100 km. However, 
as I pomted out in my paper, the interaction of 
small scale convection with large scale motions 
is hardly understood. 
