Currents, Waves and Tides

WavesMovement of Water in the Oceans

What are Ocean Waves?Ocean Waves are the large scale movement of energy through water molecules.The wave energy moves forward, the molecules dont. They just move in a circular motionThink of surfers waiting for a wave, they bob up and down, but dont travel forward as a wave (and its energy) passes beneath them.They have to kick, paddle, or be towed into a wave to ride it.

http://www.cleanvideosearch.com/media/action/yt/watch?v=7yPTa8qi5X8Video of circular motion of a water molecule, it appears to just bob up and down.How do ocean waves form?Most waves develop on the surface of the water by a disturbance such as wind.Friction between the air and water causes the wind to pull the water upward while gravity works to pull the water back down.

Wave heightWave height is determined by three thingsHow long the wind has been blowingHow much open water the wind is blowing across (fetch)The speed of the windhttp://www.pbs.org/wnet/savageseas/multimedia/wavemachine.htmlMaking waves interactive simulator

Fetch is happening!

Breaking wavesEventually a wave stops growing in size, and it will break.

When waves approach shore the water depth decreases and the wave will start feeling the bottom. As the wave feels the bottom, the circular loops of water motion change to elliptical shapes, as loops are deformed by the bottom. Eventually the steep front portion of wave cannot support the water as the rear part moves over, and the wave breaks.

Review of the formation of a wavehttp://video.search.yahoo.com/video/play;_ylt=A2KLqIV2dIZTlxIA5UT7w8QF;_ylu=X3oDMTByNDY3bGRuBHNlYwNzcgRzbGsDdmlkBHZ0aWQDBGdwb3MDNQ--?p=how+does+an+ocean+wave+form&vid=76910b320e5d940b90f90547a11fa9b8&l=2%3A44&turl=http%3A%2F%2Fts3.mm.bing.net%2Fth%3Fid%3DVN.608055962120294038%26pid%3D15.1&rurl=http%3A%2F%2Fchannel.nationalgeographic.com%2Fchannel%2Fvideos%2Fdevelopment-of-ocean-waves%2F&tit=Development+of+Ocean+Waves&c=4&sigr=12go7cnld&sigt=10qelggjb&pstcat=arts+culture+and+entertainment&age=0&fr=mcafee&tt=b

You can use your knowledge of science (weather and wave formation) to find the perfect surf spot!

Why are waves usually larger on the west coast?More fetchPrevailing westerlies wind patternSudden reduction of water depth

Parts of a waveCrest High pointTrough Low pointWave height Distance from crest to troughWavelength Distance between crests

Parts of an ocean wave

Special WavesTsunamis: Giant waves caused by seismic activityMost damaging waves travel over great distancesTsunami waves lose very little energy in the open waterWhen encountering the shoreline, friction quickly slows the bottom of the wave, allowing water to rise quicklyTsunami waves do not have to be tall to be damaging, the surge of the amount of water is the issue!Tsunamis form when energy from an underwater earthquake moves the water, rather than wind energy at the surface.

TsunamisThe wave will continue until it hits land

Some of the wave energy even reached the US.

Storm SurgeA high water event associated with significant low pressure weather disturbances (hurricane, topical storms, etc.)Low Pressure systems allow sea levels to rise (high pressure depresses sea level)High winds push water inland

Storm Surge

Rogue Waves:Greater than twice the size of surrounding wavesUnpredictable, may approach from opposite direction of normal wavesSteep sided with deep troughshttp://channel.nationalgeographic.com/channel/alien-deep/videos/rogue-waves/?source=searchvideo

Rogue wave in the Mediterranean in 2010

Surfing waveshttp://www.youtube.com/watch?v=26KzUnEbTUsSurfing one of the worlds heaviest waveshttp://www.oceanweather.com/data/Look up current wave height data in different regions of earthhttp://www.youtube.com/watch?v=5_HefhiwioE wave formation, slow but good visual explanation 3 min

Is the motion of the water caused by waves, currents, or tides? A review quiz

1. Water levels are higher than normal during a full moon.WaveCurrent Tide2. A tsunamiWaveCurrent Tide3. A constant flow of cold water from Alaska travels all the way to CaliforniaWaveCurrent Tide4. Water moving an iceberg from Greenland to the N. AtlanticWaveCurrent Tide5. A ring of moving water in a swimming pool after your friend does a cannonball in the deep end.WaveCurrent Tide6. Rivers of water that flow in a specific direction.WaveCurrent Tide7. Large, movement of water in a circular path called a gyreWaveCurrent Tide8. In oceans, the movement of energy through the waterWaveCurrent Tide9. Water moving due to differences in density (cold and salty will sink)WaveCurrent Tide10. These depend on the wind speed, distance wind traveled, and how long the wind was blowingWaveCurrent Tide11. Type of water movement that can influence a local climate.WaveCurrent Tide12. The large scale movement of water due to windWaveCurrent Tide13. Movement of water due to the moon and suns gravitational pullWaveCurrent Tide14. Water in the Northern Hemisphere moves in a clockwise direction due to the Coriolis effect.WaveCurrent Tide15. The up and down movement of water levelsWaveCurrent Tide16. Water motion pictured below: WaveCurrent Tide

17. Water motion pictured below:WaveCurrent Tide

18. Water motion pictured below:WaveCurrent Tide