Geoscience Reference
In-Depth Information
COMMA DEVELOPMENT
INSTANT OCCLUSION
FRONTAL-WAVE SEQUENCE
CCB
CCB
CCB
DRY
AIR
WCB1
WCB1
CCB
CCB
D
Figure 9.17
Schematic illustrations of vortex developments in satellite imagery. The sequences run from
bottom to top. Left: comma cloud (C) developing in a polar airstream. Center: instant occlusion from the
interaction of a polar trough with a wave on the polar front. Right: the classical frontal wave with cold and
warm conveyor belts (CCB, WCB). C = enhanced convection; D = decaying cloud band; cloud cover
stippled.
Source: After Browning (1990). By permission of the American Meteorological Society.
9.9
). The depressions that succeed the original
one form as
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
4 Frontal-wave families
Observations show that frontal waves over the
oceans, at least, do not generally occur as separate
units but in
families
of three or four (see
Figure
