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a
b
12
20
c
d
4
8
Fig. 18.13 A schematic summary of VORTEX2 data analysis of the Goshen, Wyoming
tornadogenesis case
. Schematic summarizing the evolution of a tornadic storm during its pre-
tornadic phase. The clocks represent the time until tornadogenesis. Regions of significant cyclonic
(anticyclonic) vertical vorticity are indicated by the
purple
(
yellow
) shading.
Dark gray
shading
encloses even larger cyclonic vertical vorticity. The descending reflectivity core is indicated by the
green
shading. Surface gust fronts are analyzed using
blue lines
.
Streamlines
are shown in
black
arrows
.
Vortex lines
are shown in
gray
streamers, with the sense of rotation indicated by the
gray
arrows
.In(
d
), the downward-pointing
arrow
indicates the occlusion downdraft (From
Markowski
et al.
(
2012a
,
b
))
in Fig.
18.13
, the wrap-around mechanism worked actively by the right-hand side
vortex in Fig.
18.13
corresponding to the lower and upper mesocyclones in Fig.
18.4
.
Also, it is noted that the shaded area of high vertical vorticity of Fig.
18.13
covers
both areas of the upper-level and the low-level mesocyclones, which may be formed
by the baroclinicity generated between entropic source and sink and upward tilting
horizontal vortex, respectively. It suggests that vertical superimposition of their
phases seems a key of tornadogenesis (Fig.
18.14
).
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