lecture-1738546319

Key Concepts of Oceanography

Plate Tectonics

• Convergence and Divergence:

  • Convergence: Plates come together.

  • Divergence: Plates move apart.

  • Transform: Plates slide past each other.

Mid-Ocean Ridge

• The Mid-Ocean Ridge is characterized by hydrothermal vents, especially prominent in the Atlantic Ocean.

Continental Drift and Pangaea

• Pangaea: Historical supercontinent with connections through land masses like North America (NA) and South America (SA).

• Evidence includes fossil records and geological formations like the San Andreas Fault.

Ocean Basins

• The Earth has five named oceans: Arctic, Pacific, Southern, Indian, and Atlantic.

  • Pacific Ocean: The largest and deepest ocean.

  • Southern Ocean: Has no significant landmass interrupting it.

• Approx. 30% of the ocean is 2.5 miles deep.

• Mariana Trench: The deepest part of the ocean, visited by filmmaker James Cameron.

Sea Level Changes

• Melting of land glaciers increases sea level as opposed to icebergs which do not contribute to sea level rise.

  • Last Glacial Maximum: Approximately 15,000 years ago, coastlines were significantly different due to lower sea levels.

Chemical and Physical Properties of Seawater

• Water Composition: Strong covalent polar bonds lead to high surface tension and heat capacity.

  • Latent Heat: Energy needed for phase changes (solid to liquid to gas).

  • Salinity: Average is 35 parts per thousand (ppt).

  • Freezing Point: Lower in saltwater due to salt content; seawater freezes at a lower temperature than freshwater.

Temperature and Density Stratification

• Stratification: Different layers in water formed by variations in temperature, salinity, and density.

• Thermocline: Temperature shifts markedly with depth.

• Pycnocline: Layer where density changes significantly, usually coincides with salinity stratification.

Upwelling and Downwelling

• Upwelling: Cold, nutrient-rich water rises, supporting marine life.

• Downwelling: Warm, less nutrient-dense water sinks.

Ocean Currents

• Gyres are large systems of circulating ocean currents, marked by warm and cold currents adjacent to each other.

• Gulf Stream: A major warm ocean current flowing from the Gulf of Mexico toward the North Atlantic.

• Coriolis Effect: The caused deviation due to Earth's rotation influencing wind and current direction.

Waves and Tides

• Wind Speed influences wave height; larger waves occur with stronger winds.

• Spring Tides: Occur when the Earth, Moon, and Sun are aligned, producing higher tides.

Nutrient Dynamics

• Nutrients enter oceans primarily through runoff, especially during rainfall.

• Increased nutrient levels elevate primary productivity and algal growth, impacting aquatic ecosystems.