1 / 36

MOTION IN THE OCEAN

MOTION IN THE OCEAN. Waves and Tides. Waves. A disturbance which moves through or over the surface of a fluid Mostly caused by winds (Also earthquakes, volcanoes, grav. pull) Form of great energy. Wave Characteristics. Parts of a Wave Crest = high point Trough = low point

carly-walls
Download Presentation

MOTION IN THE OCEAN

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. MOTIONIN THE OCEAN Waves and Tides

  2. Waves • A disturbance which moves through or over the surface of a fluid • Mostly caused by winds (Also earthquakes, volcanoes, grav. pull) • Form of great energy

  3. Wave Characteristics • Parts of a Wave • Crest = high point • Trough = low point • Height = vertical distance from crest to trough • Wavelength = Horizontal distance between crest to crest or trough to trough

  4. Size of Wind Generated Waves • Depends on 3 things: • Wind Speed • Wind Duration (length of time wind blows) • “Fetch” Extent of open water across which the wind can blow

  5. Water Motion in Waves • Water travels in vertical circular orbits • Wave moves, particles don’t!

  6. Importance of Waves • Shaping Coastlines • Erode cliffs • Grind rock into sand • Ecology • Returns O2 to water • Stir up food for filter feeders

  7. Types of Waves CHOP – Short period (back bays) SWELL – Long period (boat rolls; seasickness) SWASH – water up beach BACKWASH – back down

  8. Links/Videos Wave activity • http://www.montereyinstitute.org/noaa/lesson09/l9la1.html

  9. TSUNAMI = “harbor wave” in Japanese Caused by undersea quake or volcano • Wavelength = ~150 mi. • Wave height = 6” – 1’ • Can NOT perceive in boat • Speed > 500 mph Slows down to ~25 mph at shore; water builds up to ~65+ ft

  10. Tsunami Waves

  11. Indian Ocean Tsunami 2004 • http://www.montereyinstitute.org/noaa/lesson09/l9ex1.htm Indian Ocean 2004 • http://www.montereyinstitute.org/noaa/lesson09.html Global Impact • December 26, 2004 • 9+ magnitude earthquake • Indian plate slid under Burma Plate, off coast of Sumatra • 250.000 dead • 15,000 missing • 2 million displaced

  12. Tsunamis

  13. Tides The rhythmic rise and fall of the ocean’s water • High tide = rising, incoming tide, flow • Low tide = receding, outgoing tide, ebb • Slack tide = vertical movement stops

  14. Tides are very long, slow waves • They have a wave period of 12 hours 25 min • Tidal day is 24 hours 50 min

  15. 1. Gravitational pull of sun & moon on Earth What Causes Tides? • Although Sun is HUGE, Moon closer, therefore > effect • Like magnet, pulls water away from surface = TIDAL BULGE

  16. 2. Centrifugal Forces • Bulge on opposite side because centr. force > pull of moon • Produced by motions of Earth, sun, & moon

  17. Types of Tides 2x’s/month • Spring Tide • Moon and sun are in direct line with one another • Results in unusually high tidal range • Tidal Range = vertical distance between high • & low tides

  18. Neap Tide sun and moon are at right angles Pulls cancel each other out – causes a weak pull unusually low tidal range 2 x’s / month

  19. Spring vs. Neap Tides

  20. Distance bet. Moon & Earth Perigee Tides Moon closest to earth, very high tides (causes flooding) Apogee Tides Moon farthest away from earth, very low tides

  21. Types of Tides Continued • Diurnal Tides • 1 high & 1 low / day • Parts of Gulf of Mexico and Asia • Semi-Diurnal Tides • 2 high & 2 low / day • Atlantic coasts of North America and Europe • Mixed • 2 high & 2 low / day (height varies) • Pacific coast Why different types of tides?

  22. Types of Tides

  23. Importance of Tides • Expose & submerge orgs • Circulate water in bays & estuaries • Circulates food, wastes, etc • Trigger spawning (grunion, horseshoe crab)

  24. Currents • What are currents? - “Rivers” of circulating water • Causes - Wind - Rotating Earth - Density Changes

  25. Surface Ocean Currents • Broad, slow drifts; never cross equator • Wind generated; circular gyres

  26. Coriolis Effect - N. Hemis – clockwise; Right - S. Hemis – counterclockwise; Left

  27. Gulf Stream - N. Atlantic - Brings warm water from equator north along east coast of N. A. • Sometimes form eddies – circulating water that pinches off from the current

  28. IMPORTANCE OF SURF. CURRENTS NAVIGATION MIGRATION WEATHER

  29. Localized Surface Currents Longshore Current. Flows parallel to shore; move sediment

  30. RIP CURRENT - Caused by converging longshore currents - Very dangerous ; Red Flag - DO NOT fight rip current; swim parallel to shore to get out of channel

  31. Deep Ocean Currents Separated from surface currents by boundary called a “Thermohaline” (diff in densities) • Flow beneath surface; cross equator • Move North to South

  32. Importance Of Deep Currents • Upwelling • Brings deep water to surf. • Circulates nutrients up • Moves plankton & larvae

More Related