1 / 16

Unit 4.3: The Ocean

Unit 4.3: The Ocean. Origin of the oceans (a review):. Early volcanic activity Water vapor is released during volcanic explosions, condenses to liquid - “ outgassing ” Salts : mostly NaCl , but also Mg, Ca, K Mostly from chemical weathering of continental rocks, carried to ocean by rivers

corina
Télécharger la présentation

Unit 4.3: 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. Unit 4.3: The Ocean

  2. Origin of the oceans (a review): • Early volcanic activity • Water vapor is released during volcanic explosions, condenses to liquid - “outgassing” • Salts: mostly NaCl, but also Mg, Ca, K • Mostly from chemical weathering of continental rocks, carried to ocean by rivers • Outgassing contributes salts also

  3. Tides • Caused by gravitational pull of moon • High tide: areas on Earth in line with moon - pulls oceans closer to moon • Low tide: areas on Earth at right angles to moon’s pull • b/c Earth rotates, 2 high tides and 2 low tides every day • Highlow in 6 hours, 12.5 minutes • Lowhigh in 6 hours, 12.5 minutes • Sun exerts pull also, but not as strong. Why not? • b/c farther away

  4. Cumulative effects: • When moon and Sun are lined up, gravitational pull is strongest, so highest high tides of the month • “spring” tides • @ full and new moons • When moon/Earth/Sun form a right angle, gravitational pull is “weakest”, so lowest low tides of the month • “neap” tides • @ ¼ and ¾ moons

  5. III. Layers of the Ocean: • 3 ways to classify layers: • temperature, salinity, life • Layers of Temperature: • Shallow, mixed zone • Top layer; warmest b/c Sun’s radiation heats it • Transition zone • Defined by rapid change in temperature called a thermocline: • “-cline” – to lean, bend • Deep zone • Constant temperature: ≤4°C

  6. Layers of Salinity: • Average salt concentration in parts per thousand (ppt) is ~3.5% by weight or 35‰ • Surface layer has highest salinity, but varies by region: • If high evaporation, then less water, so higher salinity (Mediterranean) • If high precipitation, then more freshwater, lower salinity • Polar regions: formation of sea ice “squeezes out” salt, so higher salinity • Transition zone: rapid change in salinity • halocline: “halo-” = salt • Deep zone: salinity is fairly constant

  7. Layers of Life: Sub-classified in 3 ways: • Availability of sunlight: • Photic zone: light can penetrate, photosynthesis can occur • Varies depending on water clarity • Aphotic zone: no sunlight • Distance from shore: • Intertidal: exposed at low tide, but covered at high tide • Neritic zone: most diversity • Oceanic: open ocean, like a desert b/c less “food”

  8. Depth: • Pelagic zone: open ocean, animals swim or float • Benthic zone: bottom-dwellers • Abyssal: deep-sea bottom; high pressures, low temps • Hydrothermal sea vents: underwater hot springs • Form at rift zones near plate boundaries • Warm enough to support “chemosynthetic” life • Rich in minerals/nutrients

  9. 9

  10. Ocean Currents • Surface currents: • Speed due to pull of the wind • Direction due to Coriolis effect • Deflection of air/water due to Earth’s rotation • Northern hemisphere: currents run clockwise (to the right) • Southern hemisphere: currents run counterclockwise (to the left)

  11. Gyres - huge circular-moving current systems that dominate the ocean’s surface • Five main ocean gyres: • North Pacific Gyre, South Pacific Gyre, North Atlantic Gyre, South Atlantic Gyre, and the Indian Ocean Gyre • Trash/plastics “collect” within these gyres, can be ingested by marine organisms

  12. Upwelling: vertical movement of water due to wind Deep, cold water rises to replace warmer water on West coast of continents/East coast of oceans – why? Winds blow toward equator, paralleling the coastline. Coriolis effect pushes warm surface layer away from coast, replaced by colder water that upwells from lower ocean. California coasts ~15°C, but N. Carolina coasts ~21°C

  13. Deep Ocean Circulation: • Dependent primarily on differences in density • “thermo-”: Temperature: colder water = more dense • “haline-”: Salinity: more salt = more dense • ... called “thermohaline” current • Takes 500-2000 years for water to circulate through the thermohaline current

  14. Surface water loses heat/water to atmosphere, becomes colder/saltier, then sinks b/c more dense • Polar water is coldest, saltiest, so it sinks and is carried toward equator • @ equator, upwelling moves surface water away, replaces it with cold water from ocean bottom • Once at the surface, water heats up, and is carried toward poles • Like a global conveyor belt…

  15. Your warm-up answers for this unit:

  16. Your warm-up answers for this unit:

More Related