Conceptual Model of:

Conceptual Model of:

Wave

Cloud Structure in Satellite Image

Typical cloud configurations

• Cloud bulge at rearward edge of frontal cloud band

• Bright in all three channels• Sometimes rearward edge

of cloud bulge translucent in VIS

• Rather smooth texture• Often in WV black stripe

indication an eddy

wave

Development of cloud bulge to cloud spiral and further to occlusion spiral

wavestage

initialoccl.stage

Meteorological Physical Background

Basic ideas:Development of cloud bulge and spiral through effect of vorticity

Conveyor Belt Theory:Lower layers

• Warm conveyor belt – rising in area of wave

• Upper relative stream– at the rear of the cloud band

and wave bulge

• Saddle point in upper relative stream– immediately south,

southweast of wave bulge– rising to the N,– sinking to the S

w.c.b

u.r.s

Conveyor Belt Theory:Upper layers

• Warm conveyor belt – rising

– more to the leading edge of

the cloud band

• Upper relative stream– partly superimposed on wave

bulge

– responsible for cloud dissolution

– distinct feature in WV: black stripe overrunning frontal cloud w.c.b

u.r.s

frontal cloud

wavecloud

Selection of relevantisentropic surface:

w.c.b

u.r.s

saddlepoint

Key Parameters: Relevant numerical parameters and their

typical distribution

Surface low and temperature advection• Surface minimum low:

– in the area of the cloud bulge

• Zeroline of TA– crosses cloud bulge:

• Juxtaposition of WA - CA maxima– WA maximum within

cloud bulge

– CA maximum immediately behind in cold air

WA

CA

Surfaceminimum:

L

LWA

CA

Upper level height and vorticity advection

• Upper level trough– behind cloud

feature

• PVA maximum– partly

superimposed on cloud bulge

– partly behind

PVAmax

LPVA

Important features:

• WA maximum:– within cloud bulge of

wave

• PVA maximum– superimposed on cloud

bulge

– partly behind, in CA

WA maximum: W

W

PVA maximum: P

P

Typical weather events

• Increasing widespread precipitation

• Possibly thunderstorms in the area of the PVA

• Most intensive precipitation to be found in the area of the emerging low cloud

• Increasing surface winds; ev. Stormy winds