lecture12 oct21-bb (1)
TRANSCRIPT
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3 PM
90oF 70oF
Wa
rm
Sea breeze
860 mb
900 mb
820 mb
isobars
780 mb
H
LH
L
Co
ld
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Land breeze
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3
Daytime sea breeze
Nighttime land breeze
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Monsoon
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Seasonal breeze the monsoon
wind system is one that changes direction seasonally, blowing from one direction in summer and from the opposite direction in winter
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Seasonal breeze the monsoon
Summer where is the pressure higher between land and ocean?
Cool surface air sinking high surface pressure
Warm surface air rising low surface pressure
Wind
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Stepped Art
Seasonal breeze the monsoon
monsoon wind system is one that changes direction seasonally, blowing from one direction in summer and from the opposite direction in winterDry and cold weather in winter Moist and hot weather in summer
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Valley breeze
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Stepped Art
Upslope valley breeze daytime
-Upslope/valley breeze forms as solar radiation heats the slope of mountain
Q: What would happen for the air adjacent to the slope from
the heating?
Hot
SW
900 mb
850 mb
800 mb
750 mb
9
900 mb
850 mb
800 mb
750 mb
HL
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Katabatic winds
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Katabatic winds nighttime
Katabatic winds decent down a mountain slope
LW
11
900 mb
850 mb
800 mb
750 mb
Q: What would happen ?
900 mb
850 mb
800 mb
750 mb
Cold
Katabatic flow
Q: What would be optimal conditions for katabatic winds ?
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Katabatic winds nighttime
Katabatic winds decent down a mountain slope
LW
12
900 mb
850 mb
800 mb
750 mb
Cold
Katabatic flow
Optimal conditionso snow-covered elevated
plateauo generates a horizontal
pressure gradientH LPGF
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Fig. 7-13, p. 17913
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Advection issues on eddy flux measurements
Super-stable layer, flow separation (Yi et al., 2005)
Katabatic flow causes errors in flux measurements
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Tower-1
Tower-2
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Chinook
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1.The air at point A in the figure below will be WARMER COLDER than at B and will have a HIGHER LOWER dew point.
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Fig. 5-14, p. 119
2. Lifting by topography
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Chinook
chinooks are descending, warm and dry winds on the leeside of a mountain range
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Santa Ana winds
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Santa Ana winds created wildfire
21
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Stepped Art
Santa Ana Winds hot and dry winds that often sweep through
the LA Basin in the fall and winterwinds descend from
hot desert terrain down to the L.A. Basin
parcel becomes warmer and drier
because of compression heating
22
need a strong high
over southwestern
U.S.
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Single-Cell Model
Three-Cell Model
General Circulation of the Atmosphere
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Single-cell model of General Circulation
Q: This single cell has never observed, what important processes have we neglected?
If you assumeearth is uniformly
covered by watersun is directly over
equatorno rotationyou will end up with a
single cell patterncalled the Hadley Cellwarm air rises at the
equator, cold air sinks in the poles
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Three-cell model of General CirculationHadley cell (0-30o); Ferrel cell (30-60o); and Polar cell (60-90o)
Q: How can we draw the basic characteristics of the general circulations?
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1. draw five belts at 0, 30, and 60 degree and mark L and H on each of them
0o0o
30o 30o
60o60o
30o
60o
30o
60o
L L
H H
L L
LL
L L
H H
H H
Intertropical convergence zone
Subtropical high
Subpolar low
Subpolar low
Subtropical high
2. draw PGF from H to L
PG
F
PG
F
PG
F
PG
F
3. draw wind directions by taking into account CF
NH, deflection to right SH, deflection to left
Polar H
Polar H
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Hadley cell Thermal cell