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110
100
110
km
100
90
90
80
2
100
50
Wind speed (m sec
21
)
2
0
50
0
(a)
(b)
E
n
e
r
g
y
Phase
(c)
Figure 6.2
(a) Wind components at meteor levels in a vertical plane in one representa-
tive case, derived by Liller and Whipple (1954) from the distortion of a long-enduring
meteor trail. (b) Normalized wind profile at meteor heights, measured to the right and
to the left from the “0” position, deduced from (a) by removal of the general shear and
amplification of the residual by a factor proportional to
ρ
2
0
. (c) Pictorial representa-
tion of internal atmospheric gravity waves. Instantaneous velocity vectors are shown,
together with their instantaneous and overall envelopes. Density variations are depicted
by a background of parallel lines lying in surfaces of constant phase. Phase progression
is essentially downward in this case, and energy propagation obliquely upward; gravity
is directed vertically downward. [After Hines (1974). Reproduced with permission of the
American Geophysical Union.)
1
/
of the effect is shown in Fig. 6.2c. Many data sets show that the fluctuating com-
ponent of the neutral wind velocity increases with increasing height. Further-
more, the perturbations about the average profile are often comparable to the
mean wind.
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