wind and ocean circulation continent/ ocean contrasts land/sea breeze wind circulation ocean...
TRANSCRIPT
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
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)
= heat energy required to increase the temperature (1 K) of an amount of substance (1 g or Kg.)
More energy is required to warm/cool water (high specific heat) than soil (land).
p. 45
-
+ +
SPECIFICIC HEAT:
OHH
Water molecule
-
+ +
SPECIFICIC HEAT:
- -+ +
OHH
Water molecule
Hydrogen bonds
-
+ +
SPECIFICIC HEAT:
- -+ +
OHH
Water molecule
Hydrogen bonds
20,000 KJ
-
+ +
SPECIFICIC HEAT:
- -+ +
OHH
Water molecule
Hydrogen bonds
Water Soil
20,000 KJ
1Kg H2O 1Kg soil
-
+ +
SPECIFICIC HEAT:
- -+ +
OHH
Water molecule
Hydrogen bonds
Water Soil
20,000 KJ
1Kg H2O 1Kg soil
Specific heat:4200 KJ Kg-1 °K-1 2500 KJ Kg-1 °K-1
-
+ +
SPECIFICIC HEAT:
- -+ +
OHH
Water molecule
Hydrogen bonds
Water Soil
20,000 KJ
1Kg H2O 1Kg soil
T↑~5°K
Specific heat:4200 KJ Kg-1 °K-1 2500 KJ Kg-1 °K-1
20,000 4,200
-
+ +
SPECIFICIC HEAT:
- -+ +
OHH
Water molecule
Hydrogen bonds
Water Soil
20,000 KJ
1Kg H2O 1Kg soil
T↑~5°K
T↑8°K
Specific heat:4200 KJ Kg-1 °K-1 2500 KJ Kg-1 °K-1
20,0002,500
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.
p. 45
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)
LATENT HEAT FLUX:
Ground Heat Ground Heat
SensibleHeat
SensibleHeatLatent
Heat
Oceans Continents
LatentHeat
SINKS OFINSOLATION
LATENT HEAT FLUX:
Ground Heat Ground Heat
SensibleHeat
SensibleHeat
LatentHeat
LatentHeat
Oceans Continents
More water available to change the state of over oceans than continents. Thus proportion to Latent Heat Flux is higher
LATENT HEAT FLUX:
Ground Heat Ground Heat
SensibleHeat
SensibleHeat
LatentHeat
LatentHeat
Oceans Continents
If a higher proportion of the available insolation is diverted to Latent Heat, then a lower proportion is available for Ground and Sensible Heat
LATENT HEAT FLUX:
Ground Heat
SensibleHeat
SensibleHeat
LatentHeat
LatentHeat
Oceans Continents
If a higher proportion of the available insolation is diverted to Latent Heat, then a lower proportion is available for Ground and Sensible Heat
Ground Heat
Changes in surface and air temperatures
No changes in temperatures
Equal
3. Penetration of RadiationRadiation penetrates through the ocean/water: Transparent
Radiation does not penetrates land (energy can’t go down further): Opaque
p. 45
Land
Energy is absorbed near the surface
Oceans
Energy is transmitted deeper
into the water
PENETRATION OF RADIATION:
Oceans Continents
Liquid Solid
CONTINENTOCEAN
Dep
th
Dep
th
Greater depth of penetration in the liquid ocean compared to solid continents
Assume equal Ground Heat Flux
PENETRATION OF RADIATION:
Oceans Continents
Temperature Temperature
Liquid Solid
CONTINENTOCEAN
Dep
th
Dep
th
Equal Areas
Equal quantities of energy represent equal areas “heated”. Oceans “deep” but “cool surface” – Continents “Shallow”, but “warm surface”
CoolWarm
4. MixingWarm water surface layer can mix with cooler water below.
No such mixing occurs on land land heats up faster.
p. 45
Calm
Warm
Cooler
Coolest
MIXING:
Least Dense
Denser
Most Dense
Stable Profile – little mixing.
CalmRough
Warm
Cooler
Coolest
MIXING:
Wave Energy – surface mixing.
Global Wind Speeds
28 m.p.h
Global Wind Speeds
Rising
Global Wind Speeds
Rising
Falling
Falling
Global Wind Speeds
TRADEWINDS
Global Wind Speeds
28 m.p.h
RISINGBUTTURBULENT
Global Wind Speeds
28 m.p.h
RISINGBUTTURBULENT
Ocean-ContinentContrast in North
“Roaring Forties”“Furious Fifties”“Screaming Sixties”
CalmRough
Salty
Warm
Cooler
Coolest
MIXING:
Saline Waters – more dense, promote vertical mixing.
Global Surface SalinityWarm RisingEquatorial AirRain
Global Surface SalinityCool descending Air.Deserts.
Global Surface Salinity
Ice melting
Most ice formationon land
CalmRough
Salty
Warm
Cooler
Coolest
Cold
MIXING:
Cool surface waters – (ice melting) more dense, promote vertical mixing.
CalmRough
Salty
Warm
Cooler
Coolest
Cold
MIXING:
Cool surface waters – (ice melting) more dense, promote vertical mixing.
No equivalent processes within the continental surfaces.
No Mixing
1
43
2
Lands heat and cool faster than oceans
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.
Breeze = a type of daily thermal circulation system developed at the interface land-ocean.
LOCAL WINDS (LAND/SEA BREEZE)
Daytime development of 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)
SEA BREEZE
Night time development of land breeze.
Night:
- Land surface cools faster (H) move to the ocean
- Oceans warms up faster and became a warm low center.
LAND BREEZE
• 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).
THE STORY SO FAR!
CAN WE BRING THIS ALL TOGETHERTO EXPLAIN PATTERNS OF GLOBAL
CLIMATE?
CAN WE BRING THIS ALL TOGETHERTO EXPLAIN PATTERNS OF GLOBAL
CLIMATE?1. Oceans/Continents
CAN WE BRING THIS ALL TOGETHERTO EXPLAIN PATTERNS OF GLOBAL
CLIMATE?1. Oceans/Continents2. Surplus/Deficit Energy
CAN WE BRING THIS ALL TOGETHERTO EXPLAIN PATTERNS OF GLOBAL
CLIMATE?1. Oceans/Continents2. Surplus/Deficit Energy3. Global Pressure Belts
CAN WE BRING THIS ALL TOGETHERTO EXPLAIN PATTERNS OF GLOBAL
CLIMATE?1. Oceans/Continents2. Surplus/Deficit Energy3. Global Pressure Belts4. Pressure Gradients
CAN WE BRING THIS ALL TOGETHERTO EXPLAIN PATTERNS OF GLOBAL
CLIMATE?1. Oceans/Continents2. Surplus/Deficit Energy3. Global Pressure Belts4. Pressure Gradients5. Coriolis Effect
CAN WE BRING THIS ALL TOGETHERTO EXPLAIN PATTERNS OF GLOBAL
CLIMATE?1. Oceans/Continents2. Surplus/Deficit Energy3. Global Pressure Belts4. Pressure Gradients5. Coriolis Effect6. Wind Direction
p. 46
At Equator (Low Pressure Belt):
L intensifies over the continents hot (warm)
Ocean cool
At the SURPLUS REGION:More insolation: “continents heat faster than oceans”.
L LL
p. 46
L = Low Pressure (warmer air, low density: air rises)
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
p. 46
H = High Pressure (cooler air, high density: air sinks)
At the SURPLUS REGION:More insolation: “continents heat faster than oceans”.
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 Poles 90 lat (High Pressure):
High Pressure is intensified over continents.
Ocean Warm
continent cold
HH H
At the DEFICIT REGION:Lack of insolation: “continents cool faster than oceans”.
90°N
90°S
CO
NTIN
EN
T
CO
NTIN
EN
T
OC
EA
N
p. 46
0°
30°S
30°N
45° -60°N
45° -60°S
90°N
90°S
0°
30°S
30°N
45° -60°N
45° -60°S
90°N
90°S
Surplus
35°S
35°N
SURPLUS/DEFICIT
0°
30°S
30°N
45° -60°N
45° -60°S
90°N
90°S
SurplusD
eficitD
eficit
35°S
35°N
SURPLUS/DEFICIT
0°
30°S
30°N
45° -60°N
45° -60°S
90°N
90°S
SurplusD
eficitD
eficit
35°S
35°N
?
PRESSUREBELTS
0°
30°S
30°N
45° -60°N
45° -60°S
90°N
90°S
SurplusD
eficitD
eficit
LOW
35°S
35°N?
?
PRESSUREBELTS
0°
30°S
30°N
45° -60°N
45° -60°S
90°N
90°S
SurplusD
eficitD
eficit
LOW
HIGH
HIGH
35°S
35°N
?
?
PRESSUREBELTS
0°
30°S
30°N
45° -60°N
45° -60°S
90°N
90°S
SurplusD
eficitD
eficit
LOW
LOW
LOW
HIGH
HIGH
35°S
35°N
?
?
PRESSUREBELTS
0°
30°S
30°N
45° -60°N
45° -60°S
90°N
90°S
SurplusD
eficitD
eficit
LOW
LOW
LOW
HIGH
HIGH
HIGH
HIGH
35°S
35°N
0°
30°S
30°N
45° -60°N
45° -60°S
90°N
90°S
SurplusD
eficitD
eficit
LOW
35°S
35°N
? ??
OCEAN/LAND
0°
30°S
30°N
45° -60°N
45° -60°S
90°N
90°S
SurplusD
eficitD
eficit
35°S
35°N
LOW LOWLOW
?
?
?
??
?HIGH
HIGH
OCEAN/LAND
0°
30°S
30°N
45° -60°N
45° -60°S
90°N
90°S
SurplusD
eficitD
eficit
35°S
35°N
LOW LOWLOW
HIGH HIGH
HIGH HIGH
HIGH
HIGH
LOW
LOW
??
??
?
?
OCEAN/LAND
0°
30°S
30°N
45° -60°N
45° -60°S
90°N
90°S
SurplusD
eficitD
eficit
35°S
35°N
LOW LOWLOW
HIGH HIGH
HIGH HIGH
HIGH
HIGH
?
??
??
?
LOW
LOW
LOW LOW
LOW LOW
OCEAN/LAND
0°
30°S
30°N
45° -60°N
45° -60°S
90°N
90°S
SurplusD
eficitD
eficit
35°S
35°N
LOW LOWLOW
HIGH HIGH
HIGH HIGH
HIGH
HIGH
LOW
LOW
LOW LOW
LOW LOW
HIGH HIGH
HIGHHIGH
HIGH
HIGHOCEAN/LAND
Pressure Gradient
HIGH
HIGH
LOW
LOW
0°
30°S
30°N
45° -60°N
45° -60°S
90°N
90°S
LOW LOWLOW
HIGH HIGH
HIGH HIGH
HIGH
HIGH
LOW
LOW
LOW LOW
LOW LOW
HIGH HIGH
HIGHHIGH
HIGH
HIGHPRESSUREGRADIENT
0°
30°S
30°N
45° -60°N
45° -60°S
90°N
90°S
LOW LOWLOW
HIGH HIGH
HIGH HIGH
HIGH
HIGH
LOW
LOW
LOW LOW
LOW LOW
HIGH HIGH
HIGHHIGH
HIGH
HIGH
CORIOLISEFFECT
0°
30°S
30°N
45° -60°N
45° -60°S
90°N
90°S
LOW LOWLOW
HIGH HIGH
HIGH HIGH
HIGH
HIGH
LOW
LOW
LOW LOW
LOW LOW
HIGH HIGH
HIGHHIGH
HIGH
HIGH
HIGHNorthernSub-TropicalAnticyclone
0°
30°S
30°N
45° -60°N
45° -60°S
90°N
90°S
LOW LOWLOW
HIGH HIGH
HIGH HIGH
HIGH
HIGH
LOW
LOW
LOW LOW
LOW LOW
HIGH HIGH
HIGHHIGH
HIGH
HIGH
HIGH
PRESSUREGRADIENT
0°
30°S
30°N
45° -60°N
45° -60°S
90°N
90°S
LOW
LOW
LOW
HIGH HIGH
HIGH HIGH
HIGH
HIGH
LOW
LOW
LOW LOW
LOW LOW
HIGH HIGH
HIGHHIGH
HIGH
HIGH
HIGH
CORIOLISEFFECT
0°
30°S
30°N
45° -60°N
45° -60°S
90°N
90°S
LOW
LOW
LOW
HIGH HIGH
HIGH HIGH
HIGH
HIGH
LOW
LOW
LOW LOW
LOW LOW
HIGH HIGH
HIGHHIGH
HIGH
HIGH
HIGH
HIGHHIGHSouthernSub-TropicalAnticyclone
0°
30°S
30°N
45° -60°N
45° -60°S
90°N
90°S
LOW LOWLOW
HIGH HIGH
HIGH HIGH
HIGH
HIGH
LOW
LOW
LOW LOW
LOW LOW
HIGH HIGH
HIGHHIGH
HIGH
HIGH
HIGH
HIGHHIGH
PRESSUREGRADIENT
0°
30°S
30°N
45° -60°N
45° -60°S
90°N
90°S
LOW LOWLOW
HIGH HIGH
HIGH HIGH
HIGH
HIGH
LOW
LOW
LOW LOW
LOW LOW
HIGH HIGH
HIGHHIGH
HIGH
HIGH
HIGH
HIGHHIGH
CORIOLISEFFECT
0°
30°S
30°N
45° -60°N
45° -60°S
90°N
90°S
LOW LOWLOW
HIGH HIGH
HIGH HIGH
HIGH
HIGH
LOW
LOW
LOW LOW
LOW LOW
HIGH HIGH
HIGHHIGH
HIGH
HIGH
HIGH
HIGHHIGH
HIGHLOW
0°
30°S
30°N
45° -60°N
45° -60°S
90°N
90°S
LOW LOWLOW
HIGH HIGH
HIGH HIGH
HIGH
HIGH
LOW
LOW
LOW LOW
LOW LOW
HIGH HIGH
HIGHHIGH
HIGH
HIGH
HIGH
HIGHHIGH
HIGHLOW
PRESSUREGRADIENT
0°
30°S
30°N
45° -60°N
45° -60°S
90°N
90°S
LOW LOWLOW
HIGH HIGH
HIGH HIGH
HIGH
HIGH
LOW
LOW
LOW LOW
LOW LOW
HIGH HIGH
HIGHHIGH
HIGH
HIGH
HIGH
HIGHHIGH
HIGHLOW
CORIOLISEFFECT
0°
30°S
30°N
45° -60°N
45° -60°S
90°N
90°S
LOW LOWLOW
HIGH HIGH
HIGH HIGH
HIGH
HIGH
LOW
LOW
LOW LOW
HIGH HIGH
HIGHHIGH
HIGH
HIGH
HIGH
HIGHHIGH
HIGHLOW
LOW
LOWHIGHLOWLOW
35°N
35°S
Winds blowing represent the advection of energy in the form of Sensible Heat from the zone of Surplus to the zone of Deficit.
0°
30°S
30°N
45° -60°N
45° -60°S
90°N
90°S
HIGH
HIGH
LOW
LOW
HIGH
HIGH
LOW
HIGH
Winds blowing consistently inone direction exert friction on the surface of the oceans and move waters in the same direction.
0°
30°S
30°N
45° -60°N
45° -60°S
90°N
90°S
HIGH
HIGH
LOW
LOW
HIGH
HIGH
LOW
HIGH
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
0°
30°S
30°N
45° -60°N
45° -60°S
90°N
90°S
HIGH
HIGH
LOW
LOW
HIGH
HIGH
LOW
HIGH
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
0°
30°S
30°N
45° -60°N
45° -60°S
90°N
90°S
HIGH
HIGH
LOW
LOW
HIGH
HIGH
LOW
HIGH
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
0°
30°S
30°N
45° -60°N
45° -60°S
90°N
90°S
HIGH
HIGH
LOW
LOW
HIGH
HIGH
LOW
HIGH
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
0°
30°S
30°N
45° -60°N
45° -60°S
90°N
90°S
HIGH
HIGH
LOW
LOW
HIGH
HIGH
LOW
HIGH
East Coast of continents 20-40°Warm Surface Ocean Currents
0°
30°S
30°N
45° -60°N
45° -60°S
90°N
90°S
HIGH
HIGH
LOW
LOW
HIGH
HIGH
LOW
HIGH
West Coast of continents 20-40°Cold Surface Ocean Currents
0°
30°S
30°N
45° -60°N
45° -60°S
90°N
90°S
HIGH
HIGH
LOW
LOW
HIGH
HIGH
LOW
HIGH
East Coast of continents 50-70°Cold Surface Ocean Currents
0°
30°S
30°N
45° -60°N
45° -60°S
90°N
90°S
HIGH
HIGH
LOW
LOW
HIGH
HIGH
LOW
HIGH
West Coast of continents 50-70°Warm Surface Ocean Currents
REALITY!
ATLANTIC
0°
23.5°
23.5°
EASTCOAST
WESTCOAST
NorthAmerica
SouthAmerica
Europe
Africa
Antarctica
ATLANTIC
0°
23.5°
GulfStream
CanaryCurrent
EASTCOAST
WESTCOAST
Published by AAAS
K. L. Law et al., Science 329, 1185-1188 (2010)
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
Published by AAAS
K. L. Law et al., Science 329, 1185-1188 (2010)
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
ATLANTIC
0°
EASTCOAST
GulfStream
CanaryCurrent
WESTCOAST
BrazilianCurrent
BenguelaCurrent
ATLANTIC
0°
EASTCOAST
GulfStream
CanaryCurrent
WESTCOAST
BrazilianCurrent
BenguelaCurrent
Labrador/GreenlandCurrent
North AtlanticDrift
ATLANTIC
0°
EASTCOAST
GulfStream
CanaryCurrent
WESTCOAST
BrazilianCurrent
BenguelaCurrent
Labrador/Greenland
Current
North AtlanticDrift
West Wind DriftAt these latitudes there is no continent to contrast so winds circle globe
PACIFICEAST
COASTWESTCOAST
NorthAmerica
SouthAmerica
Asia
Australia
Antarctica
PACIFICEAST
COASTWESTCOAST
KuroshioCurrent
CaliforniaCurrent
PACIFICEAST
COASTWESTCOAST
KuroshioCurrent
CaliforniaCurrent
East Australian
Current
Chile/PeruHumboltCurrent
PACIFICEAST
COASTWESTCOAST
KuroshioCurrent
CaliforniaCurrent
East Australia
nCurrent
Chile/PeruHumboltCurrent
BeringCurrent
AlaskanCurrent
PACIFICEAST
COASTWESTCOAST
KuroshioCurrent
CaliforniaCurrent
East Australia
nCurrent
Chile/PeruHumboltCurrent
BeringCurrent
AlaskanCurrent
West Wind Drift
INDIANEAST
COASTWESTCOAST
Asia
Australia
Antarctica
Africa
INDIANEAST
COASTWESTCOAST
Agulhas/ Mozambiqu
eCurrent
WesternAustralianCurrent
INDIANEAST
COASTWESTCOAST
Agulhas/ Mozambiqu
eCurrent
WesternAustralianCurrent
West Wind Drift
INDIANEAST
COASTWESTCOAST
Agulhas/ Mozambiq
ueCurrent
WesternAustralianCurrent
West Wind Drift
Too small an ocean basin north of the Equator to establish pattern. Currents driven by seasonal winds
ANTARCTIC/SOUTHERN OCEAN
H H HAustralia
Antarctica
AfricaSouth
America
ANTARCTIC/SOUTHERN OCEAN
H H H
Southern Sub-tropical Anticyclones
ANTARCTIC/SOUTHERN OCEAN
L
H H H
L L L
Southern Sub-tropical Anticyclones
Mid-Latitude Lows
ANTARCTIC/SOUTHERN OCEAN
L
H H H
L L L
Southern Sub-tropical Anticylcones
Mid-Latitude LowsWest Wind
Drift
1. Winds moving westward
- warm Equatorial currents
0°
60°
40°
20°
N
60°
40°
20°
S
SURFACE OCEAN CURRENTS
Cold v.s. warm currents
2. Winds moving eastward
- cold currents from the poles
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.
Global Wind Circulation
IMPORTANCE OF SURFACE OCEAN CURRENTS
0°
50°
50°
Sub-Tropical High Pressure Cells
30°
30°
30°
At Local level:
They regulate air temperature on land.
e.g. San Francisco Bay Area cold surface currents cools weather even in the summer.
IMPORTANCE OF SURFACE OCEAN CURRENTS
At Global level:
Exchange of heat between low- and high-latitudes.
Weather pattern:
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 SHIFTSInter-Tropical Convergence Zone
(ITCZ)The zone where northeast and southeast trades meet, usually vicinity of the equator.
Features: instability; rising air, low pressure conditions.
June 21: northward up to 25°N. December 21: southward up to 20°S.
ITCZ Annual Shifts:
p. 48-49
NH: two high pressure centers: Pacific & Atlantic
SH: four high pressure centers: Pacific, Atlantic, Indian oceans. Also over Australia: land cools faster than ocean (SH-winter, ).
June 21: ITCZ over northern Africa, Pakistan, south- Asia.
23.5N
p. 48
NH: High pressure over continents strengthened (cold fronts).
SH: 3 large high pressure centers: Pacific, Atlantic, Indian Oceans.
December 21: ITCZ over Australia, southern Africa and South America
23.5S
p. 49