ch 21-movements of ocean

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Ch 21-Movements of Ocean. Objectives Describe how wind patterns, rotation of Earth and continental barriers affect surface currents in the ocean Major factor that determines the direction in which a surface current circulates - PowerPoint PPT Presentation


  • Ch 21-Movements of OceanObjectivesDescribe how wind patterns, rotation of Earth and continental barriers affect surface currents in the oceanMajor factor that determines the direction in which a surface current circulatesExplain how differences in density of ocean water affect the flow of deep currentsDescribe the formation of waves and the factors that affect wave sizeExplain how waves interact w/ coastlineIdentify the cause of destructive ocean wavesDescribe the gravitational pull of the moon causes tidesCompare spring tides and neap tidesDescribe how tidal oscillations affect tidal patternsExplain how the coastline affects the tidal currents

  • Factors that Affect Surface CurrentsCurrents-horizontal movement of water in well defined patternSurface currents-currents that move on or near the surface of ocean and are driven by windsControlled by air currents, Earths rotation, location of continentsWhat causes winds?Uneven heating of the atmosphereAir moves from high to low pressureColder, denser air sinks

  • Global Wind BeltsTrade winds-located just N and S of equator, push currents westwardWesterlies-push ocean currents eastward in higher latitudes of N and S HemispheresBoth affect flow of ocean surface currents

  • Rotation and Continental BarriersContinental barriers-current is deflected and divided when surface currents flow against continentCoriolis Effect-apparent curving of the path of moving object from an otherwise straight path due to Earths rotationGyres-huge circle of moving ocean water found above and below the equator

  • Major Surface CurrentsEquatorial Currents-Atlantic, Pacific, Indian. 2 warm water equatorial currents moving westCurrents in S Hemisphere-Antarctic Circumpolar Current is largest, no continent interruptionCurrents in N Atlantic-Gulf Stream moves along E coast of N America. Joins w/ Labrador current=N Atlantic current joins N Equatorial CurrentCurrents in N Pacific-similar to N Atlantic. Kuroshio current, flows northward along E coast of Asia, flows toward N America and cools drift of California

  • Deep CurrentsStream-like movement of ocean water far below the surface, slower than surface currents, form in polar regions as cold dense water sinks and flows beneath warmer ocean waterAntarctic Bottom Water-dense, cold water sinks to bt, forms deep current. Moves slowly northward to latitude of 40 deg NN Atlantic Deep Water-begins S of Greenland, flows southward under Gulf Stream, divides near equator. One flows northward, other flows southward over the Antarctic Bt WaterTurbidity Currents-strong current caused by under water landslide. What causes it do you think?

  • Sec 2-Ocean WavesWave-periodic disturbance in a solid, liquid, or gas as energy is transmitted through the mediumCrest-highest pt of waveTrough-lowest point between 2 crestsWave height-vertical distance between the crest and the trough of a waveWavelength-horizontal distance between 2 consecutive crests or between 2 consecutive troughsWave period-time required for 2 consecutive wave crests to pass a given ptWave speed- wavelength/wave period

  • Wave SizeWhat factors determine the size of wave?Speed of wind, length of time the wind blows, and fetchFetch-distance that the wind can blow across open waterSwells-long, rolling waves which are similar in size, move in groups, one waves follows anotherSteady high winds=waves equal great sizesStrong and gusty=choppy water w/ waves of great heights and lengthsWhitecaps-winds blow the crest of a wave off, allows less radiation to reach the ocean

  • Waves and CoastlineShallow water near coastline, wave touches the ocean floor, waves slow and eventually breakBreakers-top of wave continues at same speed while bt wave slows as it comes in contact w/ bt. Refraction-ocean waves bend directly toward the coastline in shallow water, shallow water wave travels slower than wave still in deep waterUndertows-irregular current, seldom strongRip current-large breakers returning to ocean through channels, cut through underwater sandbars parallel to beachLongshore Currents-waves that approach beach at an angle

  • TsunamisMost destructive wave in oceansNot powered by windGiant seismic ocean waves, caused by earthquakes on ocean floor, volcanic eruptions and under water landslidesHeight may be 30-40 m

  • Sec 3-Tides rise and fall of water level in the ocean and other large bodies of waterHow does the gravitational pull of the moon cause tides?Gravitational pull of moon is strongest on side of Earth nearest to moon. Ocean on Earths near side bulges slightly, causes high tide w/in area of bulge. Causes tidal bulge on opposite side of Earth

  • Spring and Neap TidesTidal range-difference in levels of ocean water at high tide and low tideSpring tides-Earth, sun, moon are aligned during new and full moon. Gravitational pull results in higher high tides and lower low tidesNeap tides-1st and 3rd quarter phase of moon the sun and moon are at right angles of each other, work against each other, daily tidal range is small

  • Location and Tidal RangeBaltimore, MD 1 foot, 8 inches Charleston, SC 5 feet, 10 inches Eastport, ME 19 feet, 4 inches Galveston, TX 1 foot, 5 inches Key West, FL 1 foot, 10 inches New London,CT 3 feet, 1 inch New York, NY 5 feet, 1 inch Portland, ME 9 feet, 11 inches San Diego, CA 5 feet, 9 inches San Francisco, CA 5 feet, 10 inches Vancouver, B.C 10 feet, 6 inchesBoston, MA 10 feet, 4 inches Ft. Pulaski, GA 7 feet, 6 inches Philadelphia, PA 6 feet, 9 inches St. Petersburg, FL 2 feet, 3 inches Sandy Hook, NJ 5 feet, 2 inches Seattle, WA 11 feet, 4 inches Washington, DC 3 feet, 2 inches.

  • Tidal VariationsWhat affects tidal patterns?Size, shape, depth, and location of ocean basin Tidal oscillations-slow, rocking motion of ocean water that occurs as tidal bulges move around ocean basinsWelcome to Discovery Education Player

  • Tidal CurrentsMovement of water toward and away from the coast, result of rise and fall of tidesFlood tide-when tidal currents flow toward the coastEbb tide-tidal current flow toward oceanSlack water-no tidal currentTidal currents strongest between 2 adjacent coastal regionsTidal bore-river enters the ocean through long bay, tide may enter the river mouth, surge of water rushes upstream



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