Oceans

What do you know about 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 TopographyTopography more varied with larger elevation changes than on the Earth’s surface.

Mid-oceanic ridges Mid-oceanic ridges Trenches Trenches Island arcs Island arcs Hot spots Hot spots

Fig. 15.3, p.377 Highest mountain Mt. Everest 8848 meters Average elevation of continents 840 meters Sea level Average 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 determined? determined SonarSonar: measuring the time sound waves take to return to ship Sonar 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 Dips and bumps are due to variations in gravitational force Dips and bumps are due to variations in gravitational force Sea surface copies the ocean floor surface Sea surface copies the ocean floor surface Differences are measured using the time radar signals take to travel through the atmosphere, hit the ocean’s surface, bounce back, and travel back to the satellite Differences are measured using the time radar signals take to travel through the atmosphere, hit the ocean’s surface, bounce back, and travel back to the satellite

Geosat satellite Launched in 1985 Launched in 1985 Orbits the Earth in about 14 hours Orbits the Earth in about 14 hours The Earth rotates The Earth rotates Satellite map of the Earth’s topography, 1.5 years Satellite map of the Earth’s topography, 1.5 years For every increase of 1000 meters on the seafloor, there is 1 meter increase in height of water.

Geosat image of the ocean floor

Continental margins: where land meets the sea Atlantic Ocean: plate boundary is in the center of the ocean basin, away from the continental margin

Passive margin: without a plate boundary

Active margin: contains a plate boundary

Variations in temperature: From north to south due to the Sun’s radiation

Changes in the Sun’s angle cause variations in the amount of solar energy reaching Earth’s surface.

Variations in Sun’s rays with latitude

Layers of the Ocean: what determines the ocean’s layers?

Temperature: warmer at equator cooler near the poles Surface temperature variations

Ocean basins Temperature variations within ocean basins: sketch and describe

Salinity of Seawater Water is bipolar Water is bipolar The cation sodium attaches to the negative side The cation sodium attaches to the negative side The anion chlorine attaches to the positive side The anion chlorine attaches to the positive side The figure illustrates dissolved salt The figure illustrates dissolved salt

The amount of solid material dissolved in water

Source of salts? Chemical weathering of rocks (dissolved load) Volcanic activity: outgassing

Do you think salinity varies within ocean basins or is the same? On the surface? Within the basin?

WHAT FACTORS MAY CHANGE THE SALINITY?

Precipitation

Fig. 16.4, p.402

Salinity

Precipitation and Evaporation Red-precipitation Blue-evaporation

Density: how heavy something is relative to its size What factors change the density of sea water? What factors change the density of sea water? Temperature: increase, decreases density Salinity: increase, increases density

Density determines the vertical position

Photic zone: where light penetrates; upper 600 ft or 200 m

Plankton: microscopic animals and 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 rotation causes gyres rotation

Gyres or circular patterns in the oceans create currents

Fig , p.407

The Gulf Stream Benjamin Franklin described in 1770 Much more complex

Fig , p.406 On the surface

Air Temperature is influenced by ocean currents.

Ocean currents influence climate

Upwelling Orange and yellow are areas of high chlorophyll concentrations Phytoplankton?

Upwelling Wind driven Wind driven Wind blows water away from shore Wind blows water away from shore Cold nutrient-rich water is “pulled” to the surface Cold nutrient-rich water is “pulled” to the surface

Nutrients are produced by bacterial decay of material Nutrients are produced by bacterial decay of material Phosphates, nitrates, carbonates Phosphates, nitrates, carbonates Provide nutrients for plankton (base of the food chain) Provide nutrients for plankton (base of the food chain) Upwelling: bottom waters are nutrient rich

Upwelling: where

Upwelling: significance Supplies basic nutrients for single- celled organisms Supplies basic nutrients for single- celled organisms Diatoms (plants) Diatoms (plants) Offshore Ireland Offshore Ireland Red: highest concentration

Gravitational force of the moon causes the oceans to bulge Gravitational force of the moon causes the oceans to bulge Gravitational force Gravitational force Periodic rise and fall of large bodies of water Periodic rise and fall of large bodies of water The Earth turns on its axis, taking the moon about 25 hours to make one obit in our sky The Earth turns on its axis, taking the moon about 25 hours to make one obit in our sky Two tidal peaks and troughs Two tidal peaks and troughs

Tides Fluctuations due to the interaction of the sun, moon and Earth moon Centrifugal force of the Earth helps cause tides Nova Scotia’s Bay of Funday

Spring Tides Full or new moon Full or new moon Sun and moon are aligned Sun and moon are aligned Strongest Strongest

Neap Tides Occur during quarter moons Occur during quarter moons The position of the sun and moon are at right angles The position of the sun and moon are at right angles Gravitational pull cancels Gravitational pull cancels Small increase or decrease of water level Small increase or decrease of water level

Why is the ocean blue? Intensity of water at different depths Intensity of water at different depths Absorptions is greater for longer wave lengths-red Absorptions is greater for longer wave lengths-red Ocean is blue Ocean is blue Most of the light is absorbed in the few meters of water Most of the light is absorbed in the few meters of water

Did life begin in the oceans?