CH 3 Waves and Tides

1. CH 3 Waves and Tides

2. WavesThe wind not only drives surface currents, it also causes waves

3. Fundamental Features of Water Waves Wave Crest: is the highest portion of the wave. Wave Trough: is the lowest portion of the wave. Wavelength: is the linear distance separating wave crests Wave Height: is the distance from crest to trough from An Introduction to the World's Oceans, 8th edition by K.A. Sverdrup, A.C. Duxbury, and A.B. Duxbury (2004)

4. Crest move up and forward • trough moves down and back • The water molecules don’t move anywhere they just move in circles transferring energy.

5. The faster and longer the wind blows, the larger the waves get. • The size of the wave also depends on how much open water wind affects

6. wave crests up into sharp peaks (seas) • waves begin to spread out (swells) • waves begin move into the shallows • the bottom forces the water molecules to drag • waves behind the front wave catch up • they begin to pile up getting taller and steeper until they fall forward and break creating a surf

8. Surface at any location can be affected by wind and therefore cause waves. • Waves coming from different directions, strengths, and distances can result in these waves interacting and wave cancellation. • If the crest of the two waves collides they can result in a larger wave (Rogue Wave)

10. Tide • The sea surface has been rising and falling in the rhythmic patterns known as tides • Tides alternately expose and submerge organisms • Tides are caused by the gravitational pull of the moon and sun

11. The moon’s gravity pulls the water in the ocean toward the moon • On the opposite side of the earth, furthest from the moon • the pull is weaker so the water actually bulges away from the moon because of centrifugal force • Pull towards the moon and pull toward the other side (bulging) • Deep water under the bulge and shallow away from the bulge

13. As the earth rotates the planet’s surface will alternately lie under the bulge and then away from it • High tide occurs with the point is under the bulge. • Earth takes 24 hours to complete a rotation, the pt will have two high tides and two low tides every day • The moon advances a little during the earth’s rotation • it takes earth an additional 50 minutes to line up with the moon again

14. Fig. 3.32

15. Sun produces tidal bulges, but not as strong • When the sun and moon are in line with each other (full and new moon) called spring tides. • When the sun and moon are at right angles called neap tides (moon is at the first and third quarter) • Most places are semidiurnal, two high tides and two low tides a day • Diurnal tides, only one high tide and one low tide every day. (Antarctica, Gulf of Mexico, Caribbean, and Pacific)

16. Fig. 3.33