Date post: | 23-Dec-2015 |
Category: |
Documents |
Upload: | francine-melinda-collins |
View: | 216 times |
Download: | 0 times |
OceansOceans
What do you know about What do you know about the oceans?the oceans?
Fig. 16.1, p.400
Arctic Ocean
Baltic Sea
Bay of Fundy
Persian Gulf
Atlantic Ocean
Pacific Ocean
Indian Ocean
Antarctic Ocean
Oceans cover 2/3 of the Earth’s surface.
15CO, p.374
Topography more varied with larger elevation changes than on the Earth’s surface.
• Mid-oceanic ridgesMid-oceanic ridges
• TrenchesTrenches
• Island arcsIsland arcs
• Hot spotsHot spots
Fig. 15.3, p.377
Highest mountain Mt. Everest 8848 meters
Average elevation of continents 840 meters
Sea levelAverage depth of oceans – 3800 meters
Floor of central oceans about – 5000 meters
Deepest ocean trench Mariana trench – 11,000 meters
Millions of square kilometers
Percent of Area
How is the bathymetry How is the bathymetry determined?determined?
Sonar: measuring the Sonar: measuring the time sound waves time sound waves take to return to shiptake to return to ship
Known facts: •travel time to bottom and back•Speed of sound in sea water
The distance is determined by plugging these values into a simple formula
Satellite altimetry Satellite altimetry • Dips and bumps are due Dips and bumps are due
to variations in to variations in gravitational forcegravitational force
• Sea surface copies the Sea surface copies the ocean floor surfaceocean floor surface
• Differences are Differences are measured using the time measured using the time radar signals take to radar signals take to travel through the travel through the atmosphere, hit the atmosphere, hit the ocean’s surface, bounce ocean’s surface, bounce back, and travel back to back, and travel back to the satellitethe satellite
Geosat satelliteGeosat satellite
• Launched in 1985Launched in 1985
• Orbits the Earth in Orbits the Earth in about 14 hoursabout 14 hours
• The Earth rotatesThe Earth rotates
• Satellite map of the Satellite map of the Earth’s Earth’s topography, 1.5 topography, 1.5 yearsyears For every increase of 1000
meters on the seafloor, there is 1 meter increase in height of water.
Geosat image of the ocean Geosat image of the ocean floorfloor
Continental margins: where Continental margins: where land meets the sealand meets the sea
Atlantic Ocean: plate boundary is in the center of the ocean basin, away from the continental margin
Passive marginPassive margin: without a : without a plate boundaryplate boundary
Active marginActive margin: contains a : contains a plate boundaryplate boundary
Variations in temperature:Variations in temperature:
From north to south due to the Sun’s radiation
Changes in the Sun’s angle Changes in the Sun’s angle cause variations in the cause variations in the amount of solar energy amount of solar energy reaching Earth’s surface.reaching Earth’s surface.
Variations in Sun’s rays with Variations in Sun’s rays with latitudelatitude
Layers of the Ocean: what Layers of the Ocean: what determines the ocean’s determines the ocean’s layers?layers?
Temperature: warmer at Temperature: warmer at equator cooler near the equator cooler near the polespoles
Surface temperature variations
Ocean basins
Temperature variations within Temperature variations within ocean basins: sketch and ocean basins: sketch and describe describe
Salinity of SeawaterSalinity of Seawater
• Water is bipolarWater is bipolar• The cation sodium The cation sodium
attaches to the attaches to the negative sidenegative side
• The anion chlorine The anion chlorine attaches to the attaches to the positive sidepositive side
• The figure The figure illustrates illustrates dissolved saltdissolved salt
The amount of solid The amount of solid material dissolved in watermaterial dissolved in water
Source of salts?Source of salts?Chemical weathering of Chemical weathering of rocks (dissolved load)rocks (dissolved load)
Volcanic activity: Volcanic activity: outgassingoutgassing
Do you think salinity Do you think salinity varies within ocean basins varies within ocean basins
or is the same?or is the same?
On the surface?On the surface?
Within the basin?Within the basin?
WHAT FACTORS MAY WHAT FACTORS MAY CHANGE THE SALINITY?CHANGE THE SALINITY?
Precipitation
Fig. 16.4, p.402
SalinitySalinity
Precipitation and Precipitation and EvaporationEvaporation
Red-precipitation
Blue-evaporation
Density: how heavy Density: how heavy something is relative to its something is relative to its sizesize• What factors change the density of What factors change the density of
sea water?sea water?
Temperature: increase, decreases densitySalinity: increase, increases density
Density determines the Density determines the vertical positionvertical position
Photic zone: where light Photic zone: where light penetrates; upper 600 ft or penetrates; upper 600 ft or 200 m200 m
PlanktonPlankton: : microscopic animals microscopic animals and plantsand plants
Copepod-1mm
Diatom-phytoplankton
Dinoflagellate- 250 microm.
Zooplankton
• bottom of the food chain•Use basic nutrients from sea water to produce skeletons and soft tissue• phytoplankton produce greater than 50%
Coriolis effect: earth’s Coriolis effect: earth’s rotation causes gyresrotation causes gyres
GyresGyres or circular patterns or circular patterns in the oceans create in the oceans create currentscurrents
Fig. 16.13, p.407
The Gulf StreamThe Gulf StreamBenjamin Franklin described Benjamin Franklin described in 1770in 1770 Much more complexMuch more complex
Fig. 16.12, p.406
On the surface
Air Temperature is influenced Air Temperature is influenced by ocean currents.by ocean currents.
Ocean currents influence Ocean currents influence climateclimate
UpwellingUpwelling
Orange and yellow are areas of high chlorophyll concentrations
Phytoplankton?
UpwellingUpwelling
• Wind drivenWind driven
• Wind blows water Wind blows water away from shoreaway from shore
• Cold nutrient-rich Cold nutrient-rich water is “pulled” to water is “pulled” to the surfacethe surface
• Nutrients are Nutrients are produced by produced by bacterial decay of bacterial decay of materialmaterial
• Phosphates, Phosphates, nitrates, carbonatesnitrates, carbonates
• Provide nutrients Provide nutrients for plankton (base for plankton (base of the food chain)of the food chain)
Upwelling: bottom waters Upwelling: bottom waters are nutrient richare nutrient rich
Upwelling: whereUpwelling: where
Upwelling: Upwelling: significancesignificance
• Supplies basic Supplies basic nutrients for single-nutrients for single-celled organisms celled organisms
• Diatoms (plants)Diatoms (plants)
• Offshore IrelandOffshore Ireland
Red: highest concentration
• Gravitational force of the moon Gravitational force of the moon causes the oceans to bulgecauses the oceans to bulge
• Periodic rise and fall of large bodies Periodic rise and fall of large bodies of waterof water
• The Earth turns on its axis, taking the The Earth turns on its axis, taking the moon about 25 hours to make one moon about 25 hours to make one obit in our skyobit in our sky
• Two tidal peaks and troughsTwo tidal peaks and troughs
TidesTides
Fluctuations due to the interaction of the Fluctuations due to the interaction of the sun, moon and Earthsun, moon and Earth
Centrifugal force of the Earth helps cause Centrifugal force of the Earth helps cause tidestides
Nova Scotia’s Bay of Funday
Spring TidesSpring Tides
• Full or new moonFull or new moon
• Sun and moon are alignedSun and moon are aligned
• StrongestStrongest
Neap Neap TidesTides
• Occur during quarter moonsOccur during quarter moons• The position of the sun and moon are The position of the sun and moon are
at right anglesat right angles• Gravitational pull cancelsGravitational pull cancels• Small increase or decrease of water Small increase or decrease of water
levellevel
Why is the ocean blue?Why is the ocean blue?
• Intensity of water Intensity of water at different depthsat different depths
• Absorptions is Absorptions is greater for longer greater for longer wave lengths-redwave lengths-red
• Ocean is blueOcean is blue• Most of the light is Most of the light is
absorbed in the absorbed in the few meters of few meters of waterwater
Did life begin in the oceans?Did life begin in the oceans?