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Currents & Waves

Currents & Waves. Waves. Waves are caused by wind. Crest - highest part of the wave Trough- lowest part of the wave Height- the distance between the trough and the crest. Wavelength- the distance between each wave crest or trough. http://www.mos.org/oceans/motion/wind.html. Waves Cont….

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Currents & Waves

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  1. Currents & Waves

  2. Waves • Waves are caused by wind. • Crest - highest part of the wave • Trough- lowest part of the wave • Height- the distance between the trough and the crest. • Wavelength- the distance between each wave crest or trough. • http://www.mos.org/oceans/motion/wind.html

  3. Waves Cont… • Fetch- the span of water over which the wind blows. • Seas- sharp peaks of waves. • Swells- smooth rounded crests. • When the wave crashes over it is called a break which creates a surf. • Wave reinforcement- when waves collide. • http://seacoos.org/Community%20and%20Classroom/WavesClassroom/index_html#WaveFactSheet

  4. Tsunami • Tsunami are caused by under water earth quakes. • http://www.pbs.org/wnet/savageearth/animations/tsunami/ • http://www.geophys.washington.edu/tsunami/movies/globe.mov • http://news.bbc.co.uk/1/hi/world/4136289.stm

  5. Surface Currents • Driven by wind • Coriolis effect- wind moving in a circle across the Earth due to the Earth’s rotation. • http://www.classzone.com/books/earth_science/terc/content/visualizations/es1904/es1904page01.cfm?chapter_no=visualization • http://www.classzone.com/books/earth_science/terc/content/visualizations/es1905/es1905page01.cfm?chapter_no=19

  6. Trade winds- winds that bend toward the equator. They are the steadiest winds on earth. Westerlies- these winds move in the opposite direction of the trade winds. Polar easterlies- high latitude winds. http://www.mhhe.com/biosci/genbio/tlw3/eBridge/Chp29/animations/ch29/global_wind_circulation.swf

  7. When the sea surface moves due to these winds it moves off at an angle due to the Coriolis effect. Equatorial currents - caused by the trade winds at the equator, move parallel to the equator. Due to the Coriolis effect these currents combine and create a large circular system called gyres. https://wrc.navair-rdte.navy.mil/warfighter_enc/oceans/Atlantic/lantcurr.htm http://www.classzone.com/books/earth_science/terc/content/visualizations/es1904/es1904page01.cfm?chapter_no=visualization

  8. Deep Ocean Currents • The major oceanic currents flow at various depths. These are caused by thermohaline circulation. Cold, salt-laden water is heavier than warm water and sinks into the depths. To replace it, warmer water masses flow in. These then cool and follow the sinking waters. • Ex: The Gulf stream warmed by the equatorial sun. It flows north reach the sub polar waters. From the south comes a cold water current called the Antarctic Circumpolar Current.

  9. Deep Ocean Currents Cont… • The Gulf Stream moves at up to 9 km/h - deepwater currents move very slowly, at most 0.36 km/h, so it takes about 1,000 years for water to circulate around the entire globe on these global conveyer belts. • http://www.lighthouse-foundation.org/index.php?id=101&L=1 • http://www.divediscover.whoi.edu/circulation/world.html • http://www.cru.uea.ac.uk/cru/info/thc/

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