Oceanography Notes

Oceans and Seas

General Knowledge

  • Over 70% of the Earth’s surface is covered by water.
  • 95% of that water is salt water, while only 5% is fresh water, and part of that is ice.

Learning Objectives

  • Introduce the concepts of oceans, seas, inland seas, and coastal areas.
  • Introduce the concepts of waves and tides, their causes, and their importance.

Essential Question

  • How and why do waves, tides, and currents occur, and how do they affect humans and the ocean and sea environment?

Ocean and Sea

  • An ocean is a huge body of water.
  • A sea is a smaller body of water.

Ocean and Continents

  • The earth is divided into land and water.
  • Land part is continent.
  • Water part is ocean.

Questions about Waves

  • Why does the Ocean have waves?
  • What are the parts of a wave?
  • How does water move in a wave?
  • What happens when a wave hits a beach?

Ocean Currents, Tides, and Waves

  • Ocean waters don't remain static; they move via ocean currents, tides, and waves.

Sea vs. Ocean

  • (Implied differences based on a visual with temperature readings of land, ocean, and sea)

Waves

  • A wave is the rising and falling movement of water on its surface.

Water Movement in a Wave

  • The edge of the water goes back and forth with the waves.
  • If you float an object on the ocean, it stays roughly in one place; it is not pushed forward by the waves.

Parts of a Wave

  • Crest: the highest surface part of a wave.
  • Trough: the lowest part of a wave.
  • Wave length: the distance between two adjacent crests.
  • Wave height: the vertical distance between the lowest part and the highest part.

More Wave Vocabulary

  • Frequency: the number of complete waves that occur over a given period of time, usually measured in cycles per second.
  • Amplitude: half the wave height.

Wave Formation

  • Most waves are caused by wind.
  • Friction from the wind moving over the water causes the water to move along with the wind.
  • If the wind speed is high enough, the water begins to pile up, and a wave is formed.

Water Movement in a Wave (Detailed)

  • Particles of water move around in circles.
  • The farther below the surface, the smaller the circle.
  • At a depth about equal to half the wavelength, the motion stops.

Waves Approaching the Beach

  • Wave length decreases, and wave height increases as waves approach the shore.
  • Waves drag against the bottom, and wave length decreases.

Waves at the Beach (Continued)

  • As the wave slows, its crest and trough come closer together.
  • The top of the wave is not slowed by friction and moves faster than the bottom.

Question Time

  • Why there are different types of movements in the ocean.
  • What is the difference between ocean and sea.

Brainstorming Questions

  • What is the main difference between land and sea?
  • Differentiate between a sea and an ocean?
  • Name a few oceans.

Tides

  • The oceans are always in motion.
  • Tides happen twice daily.
  • Tides are caused by the pull of gravity by the moon, and to a lesser degree by the sun.
  • The moon's gravitational pull is stronger than that of the sun because the moon is closer to the earth.

Types of Tides

  • Spring Tide: Occurs during new moon (lunar and solar tides).
  • Neap Tide: Occurs during first and third quarter moons (lunar and solar tides).

Tide Questions

  • Write the difference between Neap Tide and Spring tide.
  • Explain how gravity effects tides?

Currents

  • A current is a steady flow of water in a definite direction.
  • An ocean current refers to the flow of water within the ocean in a particular direction.
  • Depending on their temperature, they are divided into cold and warm currents.

Types of Currents

  • Surface Currents (Surface Circulation).
    • These waters make up about 10% of all the water in the ocean.
    • These waters are the upper 400 meters of the ocean.
  • Deep Water Currents (Thermohaline Circulation).
    • These waters make up the other 90% of the ocean.
    • These waters move around the ocean basins by density-driven forces and gravity.
    • The density difference is caused by different temperatures and salinity.
    • These deep waters sink into the deep ocean basins at high latitudes, where the temperatures are cold enough to cause the density to increase.

Question Time

  • Why is there a different type of movement in the ocean?

Wrap Up

  • Write the definition of sea, ocean wave, tide, and currents.