storm. With higher resolution observations, it was found that the amplifications in the
wave were associated with the movement of small scale disturbances (short waves)
within the troughs. When these short waves, which appear as constrictions in the
longer wave (figure 20), approach an area of surface low pressure, rapid development
of the cyclonic disturbance occurs.
figure 20.
Interaction: short wave trough and surface low pressure
LL
HH
LL
HH
LL
HH
LL
upper air
upper air
upper air
upper air
upper air
upper air
upper air
L
short wave
trough
L
HH
upper air
warm
L
COLD
COLD
COLD
COLD COLD
initial state
- preexisting
stationary front
may not be
present
approach of short
wave
- note constriction
in upper air flow
at trough axis
short wave
interacts with
surface low
pressure
entire wave
develops
a.
b.
c.
d.
L