15[1].3 Lecture

Ocean Waves, Tides & Ocean Waves, Tides & CurrentsCurrents

Chapter 15.3Chapter 15.3

Goal 1Goal 1

Explain waves in terms of Explain waves in terms of energy movementenergy movement

versus versus molecule movementmolecule movement

Wave CharacteristicsWave Characteristics

http://en.wikipedia.org/wiki/Image:Elliptical_trajectory_on_ripples.pnghttp://en.wikipedia.org/wiki/Image:Elliptical_trajectory_on_ripples.png

• Energy movementEnergy movement

• CrestCrest

• TroughTrough

• HeightHeight

• LengthLength– Long = fastLong = fast

Wave movement animationWave movement animation

http://www.geo.wvu.edu/~donovan/geol101/animations/27.swf

• Note the direction of energy Note the direction of energy movement and the movement of movement and the movement of water moleculeswater molecules

• Wave heightWave height– Wind speedWind speed– Wind durationWind duration– Fetch (size of body of water) Fetch (size of body of water)

• Breaking wavesBreaking waves– Friction slows trough (bottom)Friction slows trough (bottom)– Crest (top) collapses forwardCrest (top) collapses forward

Goal 2Goal 2

Discuss how tides formDiscuss how tides form

• TidesTides– Varies by location, topographyVaries by location, topography– Gravitational and Centrifugal forcesGravitational and Centrifugal forces– Moon, SunMoon, Sun– EarthEarth

Bay of Fundy Tide VideoBay of Fundy Tide Video• http://www.gma.org/undersea_landscapes/Bay_of_Fundy/http://www.gma.org/undersea_landscapes/Bay_of_Fundy/

http://www.asf.ca/CommMedia/downld/mapna2.jpg

• Spring tideSpring tide– Full / new moon = highest high tideFull / new moon = highest high tide

• Neap tideNeap tide– First / last quarter = lowest high tideFirst / last quarter = lowest high tide

Spring and Neap TidesSpring and Neap Tides

• www.decaelo.com/moongarden/ephemerides.htmwww.decaelo.com/moongarden/ephemerides.htm

Goal 3Goal 3

Understand movement of Understand movement of water via ocean currentswater via ocean currents

• Ocean currentsOcean currents– Density currentsDensity currents

•Deep water / bottom currentsDeep water / bottom currents

Deep Ocean CurrentsDeep Ocean Currents

http://science.hq.nasa.gov/oceans/images/CONVEYOR.jpghttp://science.hq.nasa.gov/oceans/images/CONVEYOR.jpg

• Surface currentsSurface currents– Driven by global wind systemsDriven by global wind systems– PredictablePredictable

•Trade windsTrade winds

•Prevailing westerliesPrevailing westerlies

•Polar easterliesPolar easterlies

• GyresGyres– Continents deflect surface currentsContinents deflect surface currents– Circular motion & Coriolis forceCircular motion & Coriolis force– Northern Hemi = ClockwiseNorthern Hemi = Clockwise– Southern Hemi = CounterclockwiseSouthern Hemi = Counterclockwise

Major Ocean CurrentsMajor Ocean Currents

US Navy Oceanographic OfficeUS Navy Oceanographic Office

http://www.learner.org/jnorth/images/graphics/n-r/OceanCurrentsUSNOO.gifhttp://www.learner.org/jnorth/images/graphics/n-r/OceanCurrentsUSNOO.gif

• UpwellingUpwelling– Cold water deflects up continentsCold water deflects up continents– Pushed out by windsPushed out by winds– West coasts & trade windsWest coasts & trade winds– Nutrient rich = fishNutrient rich = fish