Geoscience Reference
In-Depth Information
φ m
φ m
k = 0.35
k = 0.40
7
1.4
1.6
1.4
1.2
6
1.0
0.8
0.8
0.6
5
0.6
0.4
0.4
ζ k = 0.40
0.2
0.2
4
-0.10
-0.05
0.05
0.10
-0.10
-0.05
0
0.05
0.10
ζ k = 0.35
3
φ m = (1 - 15 ζ ) -1/4
2
φ 4 m - 9 ζ φ 3 m =1
φ m = 1 + 4.7 ζ
1
-2.5
-2.0
-1.5
-1.0
-0.5
0
ζ
0.5
1.0
1.5
2.0
Figure 3.14 Example of a similarity relationship as obtained from an experiment.
Here φ m as found in the Kansas 1968 experiment is given (vertical axis), as a function
of ζ (or z/L ). (From Businger et al., 1971 ). Note that the functions given in the graph
are slightly different than those used here (see Section 3.5.3 ). (© American Meteoro-
logical Society. Reprinted with permission.)
in Section 3.3.5 . Indeed, if we approximate the wind shear
u
z
by u
κ , the Richardson
number appears to be equivalent to z/L (see also Section 3.5.6 ). Thus, the same limit-
ing cases hold for z/L as for Ri f (see Figure 3.15 ):
*
z
Positive values of
Ri f and z/L indicate stable conditions (suppression of turbulence by
buoyancy).
Negative values of
Ri f and z/L indicate unstable conditions (enhancement of turbulence
by buoyancy).
Ri f or z/L equal to zero indicate neutral conditions in which buoyancy does not play a role.
Search WWH ::




Custom Search