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Ocean Waves and TidesOcean Waves and Tides
WavesWaves
•A A WaveWave is a is a rhythmicrhythmic movementmovement that carries that carries energyenergy through matter or through matter or space.space.
•In oceans, waves move In oceans, waves move through through seawaterseawater
WavesWaves
Caused byCaused by::
•WindWind
•EarthquakesEarthquakes
•Gravitational force of the Gravitational force of the Moon and Sun.Moon and Sun.
Parts of a WaveParts of a Wave
•CrestCrest – highest point of a wave – highest point of a wave
•Trough Trough – lowest point of a wave– lowest point of a wave
•Wave HeightWave Height – vertical distance – vertical distance between the crest and the troughbetween the crest and the trough
•WavelengthWavelength – horizontal distance – horizontal distance between two crests or two troughsbetween two crests or two troughs
Wavelength
Wave Height
Crest
Trough
Still Water
Wave Parts
Wave MovementWave Movement
•When a wave passes through When a wave passes through the ocean, the ocean, individual water individual water molecules move up and down molecules move up and down but they do not move forward but they do not move forward or backward.or backward.
Wave MovementWave Movement
•When a wave breaks against When a wave breaks against the shore, the shore, the crest outruns the the crest outruns the trough and the crest collapses.trough and the crest collapses.
•Called aCalled a breaker. breaker.
•In this case, water does move In this case, water does move forward and backward.forward and backward.
Waves Caused by WindWaves Caused by Wind
•When wind blows across a body of When wind blows across a body of water, water, frictionfriction causes the water to causes the water to move along with the wind.move along with the wind.
•Wave Height depends on – Wave Height depends on – – Wind speedWind speed– Distance over which the wind blowsDistance over which the wind blows– Length of time the wind blowsLength of time the wind blows
TidesTides
•The rise and fall in sea level is The rise and fall in sea level is called a called a tidetide..
•Caused by a Caused by a giant wavegiant wave..•One low-tide/high-tide cycle takes One low-tide/high-tide cycle takes
about 12 hrs and 25 min.about 12 hrs and 25 min.•Tidal rangeTidal range is the is the difference in difference in
ocean levelocean level between high-tide and between high-tide and low-tidelow-tide
What is the Tidal Range?What is the Tidal Range?
•HT = 30 ft, LT = 20 ftHT = 30 ft, LT = 20 ft
•HT = 20 ft, LT = 12 ftHT = 20 ft, LT = 12 ft
•HT = 50 ft, LT = 20 ftHT = 50 ft, LT = 20 ft
Gravitational Effect of the Gravitational Effect of the MoonMoon
•Two big bulges of water form Two big bulges of water form on the Earth:on the Earth:– one directly under the moon one directly under the moon – another on the exact opposite another on the exact opposite
sideside
•As the Earth spins, the bulges As the Earth spins, the bulges follow the moon.follow the moon.
Gravitational Effect of the Gravitational Effect of the SunSun
•Spring TidesSpring Tides– Earth, Moon, and Sun are lined Earth, Moon, and Sun are lined
upup– High Tides are higher and Low High Tides are higher and Low
Tides are lower than normalTides are lower than normal
Gravitational Effect of the Gravitational Effect of the SunSun
•Neap TidesNeap Tides– Earth, Moon, and Sun form Earth, Moon, and Sun form
right anglesright angles– High Tides are lower and Low High Tides are lower and Low
Tides are higher than normalTides are higher than normal
The EndThe End
