Geoscience Reference
In-Depth Information
Warm Occlusion
Cold Occlusion
D
B
Air Mass
2
Air Mass
2
C
A
Air Mass 1
Air Mass 1
Warm Sector
Air
Warm Sector
Air
Air Mass 1:
Cold
Air Mass 1:
Colder
Air Mass 2:
Cold
Air Mass 2:
Colder
A
B
C
D
Warm Sector
Air
Warm Sector
Air
Air Mass 1
Air Mass 1
More Statically
Stable
Air Mass 2
More Statically
Stable
Air
Mass 2
A
B
C
D
Figure 9.16
Schematic illustration of a warm and a cold occlusion in the classical model. Plan view of synoptic pattern (above) and
cross-sections along lines A-B and C-D. Colder air is shaded darker. The bottom panel illustrates proposed criteria for identifying warm
and cold occlusions based on static stability.
Source
: Above and centre from Stoelinga
et al
. (2002, p. 710, fig. 1), by permission of the American Meteorological Society. The bottom panel
is based on their new definition.
secondary lows
along the trailing edge of an extended
cold front. Each new member follows a course that is
south of its progenitor as the polar air pushes further
south to the rear of each depression in the series.
Eventually, the front trails far to the south and the cold
polar air forms an extensive meridional wedge of high
pressure, terminating the sequence.
Another pattern of development may take place on
the warm front, particularly at the point of occlusion, as
a separate wave forms and runs ahead of the parent
depression. This type of secondary is more likely with
very cold (cA, mA or cP) air ahead of the warm front,
and it tends to form when mountains bar the eastward
movement of the occlusion. This situation often occurs
