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Dynamic ocean-1
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- 3. Ocean Currents massesof ocean water that flow from one place to another develop from friction between the ocean and the wind that blows across its surface
- 4. Factors affectingsurface current patterns: pattern of global winds distribution of major landmasses Gravity Friction Coriolis effect
- 5. Pattern of OceanCurrents Gyres = huge, circular-moving current systems; large whirls of water within an ocean basin
- 6. North Pacific Gyre SouthPacific Gyre North Atlantic Gyre South Atlantic GyreIndian Ocean Gyre
- 7. 5 Main Gyres 1.North Pacific Gyre – clockwise 2. South Pacific Gyre - counterclockwise 3. North Atlantic Gyre - clockwise 4. South Atlantic Gyre - counterclockwise 5. Indian Ocean Gyre - counterclockwise
- 8. Average Surface OceanCurrents in February–March
- 9. When the windschange direction, the surface currents also reverse direction.
- 10. North Pacific Gyre 4 Major Currents 1. North Equatorial Current 2. Kuroshio Current 3. North Pacific Current 4. California Current
- 11. South Pacific Gyre 4 Main Currents 1. South Equatorial Current 2. East Australian Current 3. West Wind Drift 4. Peru Current
- 12. North Atlantic Gyre 4 Major Currents 1. North Equatorial Current 2. Gulf Stream Current 3. North Atlantic Current 4. Canary Current
- 13. South Atlantic Gyre 4 Main Currents 1. South Equatorial Current 2. Brazil Current 3. West Wind Drift 4. Benguela Current
- 14. Indian Ocean Gyre 4 Main Currents 1. South Equatorial Current 2. Agulhas Current 3. West Wind Drift 4. West Australian Current
- 15. Anyone whonavigates the oceans need to be aware of the currents.
- 16. Voyage timecan be reduced by traveling with the current
- 17. Ocean Currents InfluenceClimate When currents from low-latitude regions move to higher latitudes, they transfer heat from warmer to cooler areas on Earth. Ex: the North Atlantic Current—an extension of the warm Gulf Stream—keeps Great Britain and much of northwestern Europe warmer during the winter than one would expect for their latitudes, which are similar to the latitudes of Alaska and Labrador
- 18. Ocean Currents InfluenceClimate The prevailing westerly winds carry the moderating effects far inland. Ex: Berlin, Germany (52 degrees north latitude), has an average January temperature similar to that experienced at New York City, which lies 12 degrees latitude farther south
- 19. Ocean Currents Influence Climate Cold currents originating in cold high-latitude regions tend to moderate the warm temperatures of adjacent land areas. Ex: the cool Benguela Current off the western coast of southern Africa moderates the tropical heat along this coast. Walvis Bay (23° south latitude), a town adjacent to the Benguela Current, is 5° C (9° F) cooler in summer than Durban, which is 6° latitude farther poleward but on the eastern side of South Africa, away from the influence of the current
- 20. Ocean Currents InfluenceClimate Ocean currents play a major role in maintaining Earth’s heat balance
- 21. Deep Ocean Circulation This component of ocean circulation is a response to density differences among water masses that cause denser water to sink and slowly spread out beneath the surface also referred to as thermohaline circulation Recall: An increase in seawater density can be caused by a decrease in temperature or an increase in salinity.
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- 24. Basic Features ofthe Coastal Zone Shoreline - the line that marks the contact between land and sea Shore - the area that extends between the lowest tide level and the highest elevation on land that is affected by storm waves. Coast - extends inland from the shore as far as ocean- related features can be found. Coastline - marks the coast’s seaward edge
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- 26. Basic Features ofthe Coastal Zone Foreshore - the area exposed when the tide is out (low tide) and submerged when the tide is in (high tide). Backshore - landward of the high-tide shoreline; It is usually dry, being affected by waves only during storms. Nearshore Zone - lies between the low-tide shoreline and the line where waves break at low tide. Offshore Zone - Seaward of the nearshore zone
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- 28. Beaches an accumulationof sediment found along the landward margin of the ocean or a lake Berms - relatively flat platforms often composed of sand that are adjacent to coastal dunes or cliffs and marked by a change in slope at the seaward edge Beach face - the wet sloping surface that extends from the berm to the shoreline
- 29. Beaches are composedof whatever material is locally abundant
- 30. Waves Ocean wavesare energy traveling along the interface between ocean and atmosphere, often transferring energy from a storm far out at sea over distances of several thousand kilometers Most ocean waves derive their energy and motion from the wind. When a breeze is less than 3 kilometers (2 miles) per hour, only wavelets appear. At greater wind speeds, more stable waves gradually form and advance with the wind.
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- 32. Wave Characteristics Thetops of the waves are the crests, which are separated by troughs. Water Level – the level that the water would occupy if there were no waves. Wave Height - the vertical distance between trough and crest Wavelength - horizontal distance between successive crests (or troughs) Wave Period - the time it takes one full wave—one wavelength— to pass a fixed position
- 33. Tides daily changesin the elevation of the ocean surface Ocean tides result from the gravitational attraction exerted upon Earth by the Moon and, to a lesser extent, by the Sun Causes: The Moon’s gravitational force can cause the water to bulge on the side of Earth nearer the Moon An equally large tidal bulge is produced on the side of Earth directly opposite the Moon
- 34. Tides Because theposition of the Moon changes only moderately in a single day, the tidal bulges remain in place while Earth rotates “through” them Most places on Earth experience two high tides and two low tides each day Tidal bulges exist in fixed positions relative to the Moon
- 35. When the Moonis in the full or new position, the tidal bulges created by the Sun and Moon are aligned, there is a large tidal range on Earth, and spring tides are experienced.
- 36. When the Moonis in the first- or third-quarter position, the tidal bulges produced by the Moon are at right angles to the bulges created by the Sun. Tidal ranges are smaller, and neap tides are experienced.
- 37. Tidal Patterns 3. Mixedtidal pattern - two highs and lows of unequal heights during each tidal day 1. Diurnal - one high and low tide each tidal day 2. Semi-diurnal - two highs and lows of approximately equal heights during each tidal day