Ch. 22 Ocean Currents

Ocean Currents

• Movements of the ocean’s waters in giant “streams”

2 Major Currents:– Surface Currents– Deep Currents

Surface Currents

• Move on or near the surface• Driven by winds

Factors affecting Surface Currents:1. Wind Belts2. Rotational Effects3. Location of Continents

How do wind belts affect surface ocean currents?

• Energy from the movement of both the trade winds and westerlies is transferred to the surface of the ocean.

What are rotational effects and how do they affect ocean surface currents?

• Coriolis effect: the twisting or deflection of the ocean’s currents due to Earth’s rotation. – creates Gyres: large circles of moving water

Deep Currents

• Cold, dense currents that flow very slowly, deep beneath the surface.

How do deep Currents form?

• As cold dense water of the polar regions sinks, it flows beneath warmer ocean waters towards the equators.

• Movement is causedby density differences

Turbidity Currents

• A strong current caused by an underwater land slide.

22.2 Ocean Waves

• Waves: periodic up and down movement of water

• Wave period: time it takes for one complete wavelength to pass a given point

Wave Speed = wavelength Period

Wave energy

• Waves are caused by a transfer of wind energy to the water

If there were no wind, what would happen to the waves????

So no wind = no wave energyAdd wind = more wave energy

Water Movement in a Wave

• The individual water molecules themselves are moving very little!!!

Wave SizeThree Factors that affect wave size:

1. Speed of wind2. Amount of time the wind blows3. Fetch: distance that the wind blows

Waves and the Shore

• Breakers

• Refraction

Waves and the Shore

• Undertows• Rip Currents

• Longshore Currents

• Tsunamis

22.3 Tides

• The daily changes in the levels of the ocean

What causes tides???The gravitional interactions between the Earth

and the Moon!!!

Tidal Range

Behavior of Tides

• When the earth, moon, and sun are aligned– The combined gravitational pull causes the range

in tides.

• When the sun and moon are at right angles relative to the earth– The gravitational pulls do not act together and the

daily tidal range is small

Tidal Variations

• Influenced by the Ocean Basin’s:– Size – Shape– Depth– Location

Tidal Currents

• Flow of oceans towards and away from coasts as the tides rise and fall.– Most influential closer to coastlines

• Tidal Bore: a surge of water due to tidal currents in a long bay.

The End

• Ocean Currents Activity