Unformatted text preview:

WavesI. Wavesa. Wave- disturbance caused by the movement of energy from a source through a medium (solid, liquid, gas)b. As the energy travels, the medium moves in specific waysi. In ocean waves, the energy is moving through the water, but the water is not movingc. Transfer of energy from water particle to water particle in circular paths or orbits transmits wave energy across the ocean.i. Known as orbital waves, and occur in the boundary between two media: air and waterii. Because the wave moves forward, it is known as a progressive wave. d. Parts of a wavei. Crest = highest part of the waveii. Trough = lowest part of the wave. iii. Wave height = vertical distance between the trough and the crest.iv. Wavelength = the distance between troughs or crests. v. Period = the time a wave takes to go by any given point.e. Classifying Wavesi. Waves are classified by 1. Their disturbing force that creates thema. Wind waves are caused by windb. Seiche -Storm surge, seismic wave in an enclosed by or a sudden change in atmospheric pressure cause the resonant rocking water known as a seichec. Tsunami- Landslides, earthquakes and volcanoes can causetsunami, or seismic waved. Tides Gravitational pull of the moon and sun cause tides, a type of wave2. The extent to which the disturbing force continues to act on thema. Free waves are formed and then propagate on their owni. Ex: Wind waves, tsunami, seicheb. Forced waves are maintained by the disturbing forcei. Ex: tides3. The restoring force that tries to flatten thema. For small waves, with wavelength less than 1.73 cm, the dominant restoring force is cohesioni. Ex: Capillary waves that ripple across a puddleb. All waves with wavelengths >1.73 cm, the restoring force is gravityi. Because there is almost no friction between particles moving in a wave and the force of gravity is constant, waves can travel across ocean basins without disappearing4. Wavelengtha. Capillary waves: <1.73 cmb. Wind Waves: 60 – 150 mc. Seiche: Highly variabled. Tsunami: 200 km13e. Tide: ½ Earth’s Circumferenceii. Deep Water, Transitional water waves, Shallow Water Waves1. Characteristics of a wave mostly depend on the depth of the water their in.a. Deep water waves are in water that is deeper than about ½ its wavelengthi. ½ the wavelength is about the depth to which the energy of the wave extendsii. Wave speed- For deep water waves, the speed is equal to the wavelength divided by the periodb. Transitional waves travel through water that is between 1/20 and ½ of their wavelength.c. Shallow water waves are waves in water shallower than 1/20 their wave lengthi. Wave breaks around this pointiii. Wind Waves1. Wind waves are waves caused by wind blowing across the water2. The faster and the longer the wind blows, the bigger the waves get.3. The greater the fetch, the distance over which the wind blows unimpeded, the bigger the waves get. 4. While the wind is blowing on the water, it forms steeply peaked waves, called seas. Once away from the wind, the waves settle intoswells, which have smoothly rounded crests.5. When waves approach shore, the get pushed up by the presence of a bottom. They “pile up”, become higher and steeper until the break as surf.iv. Wind Waves Approaching shore1. Breaking Wavesa. When the wave is in water <1/2 the wavelength it ‘feels’ the bottom.b. The circular motion of the waves is interrupted and the circles become more like eclipses. c. Interaction with the bottom slows the wave. The waves energy forces it into peaksd. The wave becomes too high for its wavelength at the critical 1:7 ratio.e. The water is now moving faster than the wave and when it hits a 3:4 ratio of waveheight to length, it crashes, creating surf.2. Wave Refraction occurs when a wave line approaches the shore atan angle.a. The line does not break simultaneously.b. The part is shallower water breaks first and then the deeper parts break.c. So the waves ‘bend’, and can bend as much as 90°3. Wave Diffraction is the propagation of a wave around an obstaclea. Wave crests excite the water at the gap which generates new waves.14v. Internal Waves are subsurface waves that can form between layers of different densities1. They can be 30 m high with wavelengths over 0.8 km2. They move very slowly because the difference in density is small3. May be important in mixing nutrients and can be quite powerful.vi. Storm Surges1. Technically not a wave because it is only a crest2. Low pressure in the atmosphere causes water to dome, which can be as high as 9 m3. Can have devastating consequences because they are often combined with high wind wavesvii. Seiches1. Like the water in a bath tub, confined bodies of water will rock back and forth sometimes due to atmospheric conditions or seismicactivityviii. Tsunami1. Japanese term meaning ‘harbor wave’2. Shallow water waves caused by the rapid displacement of ocean water by landslides, icebergs, volcanic eruptions or earthquakes3. They have wavelengths up to 200 km and are therefore never in shallow water4. Move at about 212 m/sec or 470 miles/hour5. Very low steepness and a very long period (5 to 20 minutes)6. Incredibly Destructivea. >200,000 people


View Full Document

HC OCEA 101 - Waves

Download Waves
Our administrator received your request to download this document. We will send you the file to your email shortly.
Loading Unlocking...
Login

Join to view Waves and access 3M+ class-specific study document.

or
We will never post anything without your permission.
Don't have an account?
Sign Up

Join to view Waves 2 2 and access 3M+ class-specific study document.

or

By creating an account you agree to our Privacy Policy and Terms Of Use

Already a member?