Oceans What do you know about the oceans? Arctic Ocean Bay of Fundy Baltic Sea Persian Gulf Atlantic Ocean Pacific Ocean Indian Ocean Antarctic Ocean Oceans cover 2/3 of the Earth’s surface. Fig.
Download ReportTranscript Oceans What do you know about the oceans? Arctic Ocean Bay of Fundy Baltic Sea Persian Gulf Atlantic Ocean Pacific Ocean Indian Ocean Antarctic Ocean Oceans cover 2/3 of the Earth’s surface. Fig.
Oceans What do you know about the oceans? Arctic Ocean Bay of Fundy Baltic Sea Persian Gulf Atlantic Ocean Pacific Ocean Indian Ocean Antarctic Ocean Oceans cover 2/3 of the Earth’s surface. Fig. 16.1, p.400 Topography more varied with larger elevation changes than on the Earth’s surface. 15CO, p.374 • • • • Mid-oceanic ridges Trenches Island arcs Hot spots 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 Fig. 15.3, p.377 How is the bathymetry determined? Sonar: measuring the time sound waves take 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 • Dips and bumps are due • • to variations in gravitational force 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 Geosat satellite • Launched in 1985 • Orbits the Earth in • • about 14 hours The Earth rotates 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 Temperature variations within ocean basins: sketch and describe Ocean basins Salinity of Seawater • Water is bipolar • The cation sodium • • attaches to the negative side The anion chlorine attaches to the positive side 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? 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 Diatom-phytoplankton • bottom of the food chain •Use basic nutrients from sea water to produce skeletons and soft tissue • phytoplankton produce greater than 50% Zooplankton Dinoflagellate- 250 microm. Copepod1mm Coriolis effect: earth’s rotation causes gyres Gyres or circular patterns in the oceans create currents Fig. 16.13, p.407 The Gulf Stream Benjamin Franklin described in 1770 Much more complex On the surface Fig. 16.12, p.406 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 blows water • away from shore Cold nutrient-rich water is “pulled” to the surface Upwelling: bottom waters are nutrient rich • Nutrients are • • produced by bacterial decay of material Phosphates, nitrates, carbonates Provide nutrients for plankton (base of the food chain) Upwelling: where Upwelling: significance • Supplies basic • • nutrients for singlecelled organisms Diatoms (plants) Offshore Ireland Red: highest concentration • Gravitational force of the moon causes the oceans to bulge • 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 • Two tidal peaks and troughs Fluctuations due to the interaction of the sun, moon and Earth Centrifugal force of the Earth helps cause tides Tides Nova Scotia’s Bay of Funday Spring Tides • Full or new moon • Sun and moon are aligned • Strongest Neap Tides • Occur during quarter moons • The position of the sun and moon are at right angles • Gravitational pull cancels • Small increase or decrease of water level Why is the ocean blue? • Intensity of water at • • • different depths Absorptions is greater for longer wave lengths-red Ocean is blue Most of the light is absorbed in the few meters of water Did life begin in the oceans?