WIND AND OCEAN CIRCULATION
Continent/ Ocean contrasts
Land/Sea Breeze
Wind Circulation
Ocean Currents
DIFFERENCES IN OCEANIC AND CONTINENTAL
THERMAL PROPERTIES
Land heats & cools more rapidly than oceans. This is why:
1. Specific Heat
= heat energy required to increase the temperature (1
K) of an amount of substance (1 g or Kg.)
Water: 4,200 joules.gr-1.K-1 (4.2 J.Kg-1.K-1)
Soil (land): 2500 joules.gr-1.K-1 (0.80 J.Kg-1.K-1)
More energy is required to warm/cool water (high specific
heat) than soil (land).
p. 45
SPECIFICIC HEAT:
Water molecule
+
+
H
O
-
H
SPECIFICIC HEAT:
Water molecule
+
+
H
O
-
H
Hydrogen bonds
-
+
+
SPECIFICIC HEAT:
Water molecule
+
+
H
O
-
20,000 KJ
H
Hydrogen bonds
-
+
+
SPECIFICIC HEAT:
Water molecule
+
+
H
O
-
20,000 KJ
H
Hydrogen bonds
1Kg H2O
-
+
+
Water
Soil
1Kg soil
SPECIFICIC HEAT:
Water molecule
+
+
H
O
-
20,000 KJ
H
Specific heat:
4200 KJ Kg-1 °K-1
Hydrogen bonds
1Kg H2O
-
+
+
Water
2500 KJ Kg-1 °K-1
Soil
1Kg soil
SPECIFICIC HEAT:
Water molecule
+
+
H
O
-
20,000 KJ
H
Specific heat:
4200 KJ Kg-1 °K-1
Hydrogen bonds
1Kg H2O
-
+
+
Water
20,000
4,200
T↑~5°K
2500 KJ Kg-1 °K-1
Soil
1Kg soil
SPECIFICIC HEAT:
Water molecule
+
+
H
O
-
20,000 KJ
H
Specific heat:
4200 KJ Kg-1 °K-1
Hydrogen bonds
1Kg H2O
-
+
+
Water
T↑~5°K
2500 KJ Kg-1 °K-1
Soil
20,000
2,500
T↑8°K
1Kg soil
2. Latent Heat
-more evaporation occurs on water surfaces
 more energy is used as Latent Heat (i.e.) delays the
warm up of the water/ocean temperature
- p. 32 (540 cal/gram)
Lower evaporation occurs on soils
- not much latent heat used  land warms up
faster.
You can experience the cooling effects of evaporation when you come out of a swimming
pool. You feel cold. This is caused by the water on your skin taking energy from your body
to evaporate (you eventually dry out)
p. 45
LATENT HEAT FLUX:
SINKS OF
INSOLATION
Sensible
Heat
Latent
Heat
Ground Heat
Oceans
Latent
Heat
Sensible
Heat
Ground Heat
Continents
LATENT HEAT FLUX:
More water available
to change the state of
over oceans than
continents. Thus
proportion to Latent
Heat Flux is higher
Sensible
Heat
Latent
Heat
Ground Heat
Oceans
Latent
Heat
Ground Heat
Continents
Sensible
Heat
LATENT HEAT FLUX:
If a higher proportion of
the available insolation
is diverted to Latent
Heat, then a lower
proportion is available
for Ground and Sensible
Heat
Sensible
Heat
Latent
Heat
Ground Heat
Oceans
Latent
Heat
Ground Heat
Continents
Sensible
Heat
LATENT HEAT FLUX:
If a higher proportion of
the available insolation
is diverted to Latent
Heat, then a lower
proportion is available
for Ground and Sensible
Heat
Sensible
Heat
Equal
Latent
Heat
Ground Heat
No changes in
temperatures
Oceans
Latent
Heat
Sensible
Heat
Ground Heat
Continents
Changes in
surface and
air
temperatures
3. Penetration of Radiation
Radiation penetrates through the ocean/water: Transparent
Radiation does not penetrates land (energy can’t go down further):
Opaque
Energy is absorbed
near the surface
Land
Energy is transmitted
deeper into the water
Oceans
p. 45
PENETRATION OF RADIATION:
Continents
CONTINENT
Depth
Oceans
OCEAN
Depth
Greater depth of
penetration in the
liquid ocean
compared to solid
continents
Assume equal
Ground Heat
Flux
Liquid
Solid
Continents
CONTINENT
Warm
Depth
Depth
PENETRATION OF RADIATION:
Equal quantities
of energy
represent equal
areas “heated”.
Oceans “deep” but
“cool surface” –
Continents
OCEAN
Cool Oceans
“Shallow”, but
“warm surface”
Liquid
Temperature
Solid
Temperature
4. Mixing
Warm water surface layer can mix with cooler water
below.
No such mixing occurs on land  land heats up faster.
p. 45
MIXING:
Warm
Least Dense
Cooler
Denser
Coolest
Most Dense
Stable Profile
– little mixing.
MIXING:
Warm
Cooler
Coolest
Wave Energy –
surface mixing.
Global Wind Speeds
28 m.p.h
Global Wind Speeds
Rising
Global Wind Speeds
Falling
Rising
Falling
Global Wind Speeds
TRADE
WINDS
Global Wind Speeds
RISING
BUT
TURBULENT
28 m.p.h
Ocean-Continent
Contrast in North
Global Wind Speeds
RISING
BUT
TURBULENT
“Roaring Forties”
“Furious Fifties”
“Screaming Sixties”
28 m.p.h
MIXING:
Warm
Cooler
Coolest
Saline Waters –
more dense,
promote vertical
mixing.
Global Surface Salinity
Warm Rising
Equatorial Air
Rain
Global Surface Salinity
Cool descending
Air.
Deserts.
Global Surface Salinity
Ice melting
Most ice formation
on land
MIXING:
Warm
Cooler
Coolest
Cool surface
waters – (ice
melting) more
dense, promote
vertical
mixing.
MIXING:
Warm
Cooler
Coolest
Cool surface
waters – (ice
melting) more
dense, promote
vertical
mixing.
No equivalent processes within the continental surfaces.
2
3
4
No Mixing
1
Lands heat and cool faster than oceans
LOCAL WINDS (LAND/SEA BREEZE)
Breeze = a type of daily thermal circulation system
developed at the interface land-ocean.
Atmospheric pressure gradient is produced by the
dissimilar heating and cooling characteristics of land and
water,
- causes local air to flow differently during days
and nights.
SEA BREEZE
Day:
- warm air rises over land  moves to the ocean
- surface winds over the oceans bring cool air to the land
(H to L)
Daytime
development
of sea breeze
Night:
LAND BREEZE
- Land surface cools faster (H)  move to the ocean
- Oceans warms up faster and became a warm low center.
Night time
development
of land
breeze.
THE STORY SO FAR!
•Differences in Specific Heat.
•Differences in Latent Heat Flux.
•Differences in the Penetration of Radiation.
•Differences in Mixing.
In a zone or time of EXCESS ENERGY, Oceans warm up more slowly that continents
(continents warm faster).
In a zone or time of DEFICIT ENERGY, Oceans cool down more slowly that continents
(continents cool down faster).
CAN WE BRING THIS ALL TOGETHER
TO EXPLAIN PATTERNS OF GLOBAL
CLIMATE?
CAN WE BRING THIS ALL TOGETHER
TO EXPLAIN PATTERNS OF GLOBAL
CLIMATE?
1. Oceans/Continents
CAN WE BRING THIS ALL TOGETHER
TO EXPLAIN PATTERNS OF GLOBAL
CLIMATE?
1. Oceans/Continents
2. Surplus/Deficit Energy
CAN WE BRING THIS ALL TOGETHER
TO EXPLAIN PATTERNS OF GLOBAL
CLIMATE?
1. Oceans/Continents
2. Surplus/Deficit Energy
3. Global Pressure Belts
CAN WE BRING THIS ALL TOGETHER
TO EXPLAIN PATTERNS OF GLOBAL
CLIMATE?
1.
2.
3.
4.
Oceans/Continents
Surplus/Deficit Energy
Global Pressure Belts
Pressure Gradients
CAN WE BRING THIS ALL TOGETHER
TO EXPLAIN PATTERNS OF GLOBAL
CLIMATE?
1.
2.
3.
4.
5.
Oceans/Continents
Surplus/Deficit Energy
Global Pressure Belts
Pressure Gradients
Coriolis Effect
CAN WE BRING THIS ALL TOGETHER
TO EXPLAIN PATTERNS OF GLOBAL
CLIMATE?
1.
2.
3.
4.
5.
6.
Oceans/Continents
Surplus/Deficit Energy
Global Pressure Belts
Pressure Gradients
Coriolis Effect
Wind Direction
p. 46
At the SURPLUS REGION:
More insolation: “continents heat faster than oceans”.
At Equator (Low Pressure Belt):
L intensifies over the continents  hot (warm)
Ocean  cool
L
L
L
L = Low Pressure (warmer air, low density: air rises)
p. 46
At the SURPLUS REGION:
More insolation: “continents heat faster than oceans”.
At Sub-Tropical H Belt (30° lat.):
High pressure is intensified over “cooler” oceans.
Oceans become cooler than continents.
Oceans  colder
Continent  warmer
H
H
H
H = High Pressure (cooler air, high density: air sinks)
p. 46
At the DEFICIT REGION:
Lack of insolation: “continents cool faster than oceans”.
At Planetary Front 45-60 lat (Low Pressure):
Low pressure is intensified over the oceans
(warm/hot)
Continent  cool
Ocean  warm
L
L
L
At the DEFICIT REGION:
Lack of insolation: “continents cool faster than oceans”.
At the Poles 90 lat (High Pressure):
High Pressure is intensified over continents.
Ocean  Warm
continent  cold
H
H
H
CONTINENT
OCEAN
CONTINENT
90°N
p. 46
90°S
90°N
45° 60°N
30°N
0°
30°S
45° 60°S
90°S
90°N
SURPLUS/
DEFICIT
45° 60°N
35°N
30°N
Surplus
0°
30°S
35°S
45° 60°S
90°S
90°N
45° 60°N
35°N
30°N
Surplus
0°
Deficit
30°S
35°S
45° 60°S
90°S
Deficit
SURPLUS/
DEFICIT
90°N
0°
Surplus
?
45° 60°N
35°N
30°N
Deficit
30°S
35°S
45° 60°S
90°S
Deficit
PRESSURE
BELTS
90°N
?
?
0°
Surplus
LOW
45° 60°N
35°N
30°N
Deficit
30°S
35°S
45° 60°S
90°S
Deficit
PRESSURE
BELTS
PRESSURE
BELTS
LOW
0°
HIGH
30°S
35°S
45° 60°S
90°S
Deficit
?
Surplus
HIGH
45° 60°N
35°N
30°N
Deficit
?
90°N
90°N
LOW
0°
HIGH
30°S
35°S
45° 60°S
?
90°S
Deficit
LOW
Surplus
HIGH
45° 60°N
35°N
30°N
LOW
Deficit
?
PRESSURE
BELTS
LOW
HIGH
45° 60°N
35°N
30°N
LOW
0°
HIGH
30°S
35°S
45° 60°S
HIGH
90°S
Deficit
LOW
Deficit
90°N
Surplus
HIGH
90°N
?
?
?
0°
Surplus
LOW
45° 60°N
35°N
30°N
Deficit
30°S
35°S
45° 60°S
90°S
Deficit
OCEAN/
LAND
90°N
HIGH
?
?
HIGH
?
LOW
?
?
0°
Surplus
LOW
?
45° 60°N
35°N
30°N
Deficit
30°S
35°S
45° 60°S
90°S
Deficit
OCEAN/
LAND
90°N
LOW
?
?
?
?
?
0°
30°S
35°S
45° 60°S
90°S
Deficit
LOW
LOW
45° 60°N
35°N
30°N
Surplus
LOW
?
Deficit
OCEAN/
LAND
?
?
LOW
45° 60°N
35°N
30°N
LOW
?
?
90°S
Deficit
30°S
35°S
45° 60°S
LOW
?
0°
Surplus
LOW
90°N
Deficit
OCEAN/
LAND
?
90°N
LOW
LOW
30°S
35°S
45° 60°S
90°S
Deficit
LOW
0°
Surplus
LOW
45° 60°N
35°N
30°N
Deficit
OCEAN/
LAND
Pressure Gradient
LO
W
90°N
PRESSURE
GRADIENT
LOW
45° 60°N
30°N
LOW
LOW
0°
30°S
LOW
45° 60°S
90°S
90°N
LOW
CORIOLIS
EFFECT
45° 60°N
30°N
LOW
LOW 0°
30°S
LOW
45° 60°S
90°S
90°N
LOW
Northern
Sub-Tropical
Anticyclone
45° 60°N
30°N
LOW
LOW 0°
30°S
LOW
45° 60°S
90°S
90°N
PRESSURE
GRADIENT
LOW
45° 60°N
30°N
LOW
LOW 0°
30°S
LOW
45° 60°S
90°S
90°N
LO
W
CORIOLIS
EFFECT
45° 60°N
30°N
LO
W
LO
W
0°
30°S
LO
W
45° 60°S
90°S
90°N
LOW
45° 60°N
30°N
LOW
LOW 0°
Southern
Sub-Tropical
Anticyclone
30°S
LOW
45° 60°S
90°S
90°N
PRESSURE
GRADIENT
LOW
45° 60°N
30°N
LOW
LOW 0°
30°S
LOW
45° 60°S
90°S
90°N
LOW
CORIOLIS
EFFECT
45° 60°N
30°N
LOW
LOW 0°
30°S
LOW
45° 60°S
90°S
90°N
LO
W
45° 60°N
30°N
LOW
LOW 0°
30°S
LOW
45° 60°S
90°S
90°N
PRESSURE
GRADIENT
LO
W
45° 60°N
30°N
LOW
LOW 0°
30°S
LOW
45° 60°S
90°S
90°N
LO
W
CORIOLIS
EFFECT
45° 60°N
30°N
LOW
LOW 0°
30°S
LOW
45° 60°S
90°S
90°N
Winds blowing
represent the
advection of
energy in the
form of
Sensible Heat
from the zone
of Surplus to
the zone of
Deficit.
LO
W
LOW
45° 60°N
35°N
30°N
LOW
0°
30°S
LO
LO
W
W
45° 60°S
90°S
35°S
Winds blowing
consistently in
one direction
exert friction
on the surface
of the oceans
and move
waters in the
same direction.
90°N
LO
W
45° 60°N
30°N
0°
30°S
LO
LO
W
W
45° 60°S
90°S
Winds blowing
from a position
closer to the
equator towards
one further from
the equator
transfer warmer
water (+ ground
heat flux
towards the
poles.
Warm Surface
Ocean Currents
90°N
LO
W
45° 60°N
30°N
0°
30°S
LO
LO
W
W
45° 60°S
90°S
Winds blowing
from a position
closer to the
equator towards
one further from
the equator
transfer warmer
water (+ ground
heat flux)
towards the
poles.
Warm Surface
Ocean Currents
90°N
LO
W
45° 60°N
30°N
0°
30°S
LO
LO
W
W
45° 60°S
90°S
90°N
LO
W
Winds blowing
from a position
closer to the
poles towards
one closer to the
equator transfer
cool water ( ground heat
flux) towards
the equator.
Cold Surface
Ocean Currents
45° 60°N
30°N
0°
30°S
LO
LO
W
W
45° 60°S
90°S
90°N
LO
W
Winds blowing
from a position
closer to the
poles towards
one closer to the
equator transfer
cool water ( ground heat
flux) towards
the equator.
Cold Surface
Ocean Currents
45° 60°N
30°N
0°
30°S
LO
LO
W
W
45° 60°S
90°S
90°N
LO
W
45° 60°N
30°N
East Coast of
continents 2040°
Warm Surface
Ocean Currents
0°
30°S
LO
LO
W
W
45° 60°S
90°S
90°N
LO
W
45° 60°N
30°N
West Coast of
continents 200°40°
Cold Surface
Ocean
Currents
30°S
LO
LO
W
W
45° 60°S
90°S
90°N
LO
W
45° 60°N
30°N
East Coast of
continents
50-70°
Cold Surface
Ocean
Currents
0°
30°S
LO
LO
W
W
45° 60°S
90°S
90°N
LO
W
45° 60°N
30°N
West Coast of
continents
50-70°
0°
Warm
Surface
Ocean
30°S
Currents
LO
LO
W
W
45° 60°S
90°S
REALITY!
ATLANTIC
EAST
COAST
WEST
COAST
Europe
North
America
23.5°
Africa
0°
South
America
23.5°
Antarctica
ATLANTIC
EAST
COAST
Gulf
Stream
WEST
COAST
Canary
Current
0°
23.5°
Fig. 1 Distribution of plastic marine debris collected in 6136 surface plankton net tows on annually
repeated cruise tracks from 1986 to 2008 in the western North Atlantic Ocean and Caribbean Sea
K. L. Law et al., Science 329, 1185-1188 (2010)
Published by AAAS
Fig. 2 Average plastic concentration (color shading, units of pieces km-2) computed in 0.5{degrees}
bins and smoothed with a 700-km width Gaussian filter
K. L. Law et al., Science 329, 1185-1188 (2010)
Published by AAAS
ATLANTIC
EAST
COAST
Gulf
Stream
WEST
COAST
Canary
Current
0°
Brazilian
Current
Benguela
Current
ATLANTIC
EAST
COAST
Labrador/
Greenland
Current
Gulf
Stream
WEST
COAST
North Atlantic
Drift
Canary
Current
0°
Brazilian
Current
Benguela
Current
ATLANTIC
EAST
COAST
Labrador/
Greenland
Current
Gulf
Stream
WEST
COAST
North Atlantic
Drift
Canary
Current
0°
Brazilian
Current
At these latitudes
there is no
continent to
contrast so winds
circle globe
Benguela
Current
West Wind Drift
PACIFIC
EAST
COAST
WEST
COAST
Asia
North
America
South
America
Australia
Antarctica
PACIFIC
EAST
COAST
Kuroshio
Current
WEST
COAST
California
Current
PACIFIC
EAST
COAST
WEST
COAST
Kuroshio
Current
California
Current
East
Australian
Current
Chile/Peru
Humbolt
Current
PACIFIC
EAST
COAST
Bering
Current
WEST
COAST
Alaskan
Current
Kuroshio
Current
California
Current
East
Australian
Current
Chile/Peru
Humbolt
Current
PACIFIC
EAST
COAST
Bering
Current
WEST
COAST
Alaskan
Current
Kuroshio
Current
California
Current
East
Australian
Current
Chile/Peru
Humbolt
Current
West Wind Drift
INDIAN
EAST
COAST
WEST
COAST
Asia
Africa
Australia
Antarctica
INDIAN
EAST
COAST
Agulhas/
Mozambique
Current
WEST
COAST
Western
Australian
Current
INDIAN
EAST
COAST
Agulhas/
Mozambique
Current
WEST
COAST
Western
Australian
Current
West Wind Drift
INDIAN
EAST
COAST
Too small an ocean basin
north of the Equator to
establish pattern.
Currents driven by
seasonal winds
Agulhas/
Mozambique
Current
WEST
COAST
Western
Australian
Current
West Wind Drift
ANTARCTIC/SOUTHERN OCEAN
H
South
America
H
Africa
Antarctica
H
Australia
ANTARCTIC/SOUTHERN OCEAN
Southern Sub-tropical Anticyclones
H
H
H
ANTARCTIC/SOUTHERN OCEAN
Southern Sub-tropical Anticyclones
H
H
L
Mid-Latitude Lows
L
H
L
L
ANTARCTIC/SOUTHERN OCEAN
Southern Sub-tropical Anticylcones
H
H
L
Mid-Latitude Lows
L
H
L
L
West Wind
Drift
SURFACE OCEAN CURRENTS
N
Cold v.s. warm currents
60°
1. Winds moving westward
40°
- warm Equatorial currents
20°
0°
2. Winds moving eastward
- cold currents from the
poles
20°
40°
60°
S
IMPORTANCE OF SURFACE OCEAN CURRENTS
Global Wind Circulation
Given the strengthening of Anti-cyclones (H) over the oceans
at 30° lat.,
- they control global circulation
- feeding trades easterlies toward Equator
- westerlies toward higher latitudes.
Eastern side of anti-cyclonic cell “sends” cold and dry air to west
coasts of continents: Dry Coasts.
Western side of anti-cyclonic cell “sends” warm and wet air to east
coasts of continents: Wet Coasts.
Sub-Tropical High Pressure Cells
50°
30°
0°
30°
50°
30°
IMPORTANCE OF SURFACE OCEAN CURRENTS
Weather pattern:
At Global level:
Exchange of heat between low- and high-latitudes.
At Local level:
They regulate air temperature on land.
e.g. San Francisco Bay Area  cold surface
currents cools weather even in the summer.
p. 47
Big 8
p. 47
• Why did Columbus sail the ocean blue?
1492 – Columbus sailed the ocean blue!!
just to follow the ocean current !!
Slave trade route
SEASONAL SHIFTS
Inter-Tropical Convergence Zone (ITCZ)
The zone where northeast and southeast trades meet,
usually vicinity of the equator.
Features: instability; rising air, low pressure conditions.
ITCZ Annual Shifts:
June 21: northward up to 25°N.
December 21: southward up to 20°S.
p. 48-49
June 21: ITCZ over northern Africa, Pakistan, south- Asia.
SH: four high pressure centers: Pacific, Atlantic, Indian
oceans. Also over Australia: land cools faster than ocean
(SH-winter, ).
23.5N
NH: two high pressure centers: Pacific & Atlantic
p. 48
December 21: ITCZ over Australia, southern Africa and
South America
23.5S
NH: High pressure over continents strengthened (cold
fronts).
SH: 3 large high pressure centers: Pacific, Atlantic, Indian
Oceans.
p. 49