3 PM

90oF 70oF

Wa

rm

Sea breeze

860 mb

900 mb

820 mb

isobars

780 mb

H

LH

L

Co

ld

Land breeze

3

Daytime sea breeze

Nighttime land breeze

Monsoon

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

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

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

Valley breeze

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

Katabatic winds

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 ?

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

Fig. 7-13, p. 17913

Advection issues on eddy flux measurements

Super-stable layer, flow separation (Yi et al., 2005)

Katabatic flow causes errors in flux measurements

Tower-1

Tower-2

Chinook

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.

Fig. 5-14, p. 119

2. Lifting by topography

19

Chinook

chinooks are descending, warm and dry winds on the leeside of a mountain range

Santa Ana winds

Santa Ana winds created wildfire

21

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.

Single-Cell Model

Three-Cell Model

General Circulation of the Atmosphere

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

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?

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

Hadley cell Thermal cell