Ocean Currents

OCEAN CURRENTS

HOW DOES WATER MOVE IN THE OCEAN?

• STREAM LIKE” MOVEMENTS OF WATER

• SURFACE CURRENTS: occur near the surface and are caused by wind.

  • Surface currents usually reach depths of 100 meters, but some can be as deep as 1000 km.

  • Example: The Gulf Stream.

WHAT ARE OCEAN CURRENTS?

1. CONTINENTAL DEFLECTIONS: Currents change direction when they meet continents.

2. Coriolis Effect: Deflection of moving objects from a straight path due to Earth’s rotation. Deflection means to “turn away” or “turning aside”. Example: wind and water traveling south from the North Pole actually go towards the southwest instead of straight south because of the rotation of earth.

WHAT AFFECTS SURFACE CURRENTS?

​In the Northern Hemisphere currents are deflected to the right, and in the Southern Hemisphere to the left.

3. Global Winds: winds that blow across the surface of Earth’s oceans push water across Earth’s surface.

WHAT AFFECTS SURFACE CURRENTS? cont...

The Sun: heats up the water in the equator and causes pressure changes. Warm water goes up (less dense), cool water goes down (more dense).

WHAT POWERS SURFACE CURRENTS?

​As a result, there are differences in pressure in the atmosphere. Winds form as a result of differences in air pressure and create surface currents.

• Deep Currents occur far below the surface and they are caused by differences in water density and temperature.

  • Salinity affects the density of water (more salt more density) and Cold water is denser than warm water.

• Surface wind-driven currents generate upwelling currents in conjunction with landforms, creating deep water currents.

HOW DO DEEP CURRENTS FORM?

CONVECTION CURRENTS

​Movement of water that results from density differences.

During Upwelling, cold nutrient-rich (Iron, Nitrate) water from the deep ocean rises to the surface.

WHAT IS UPWELLING?

​This process is EXTREMELY important for life because the nutrients that are brought to the surface support the growth of phytoplankton and zooplankton.

Ocean water circulates through all of Earth’s ocean basins.

Global circulation transports energy in the form of heat, matter like salt (NaCl), nutrients (N, P) and gases like O2 ,N, CO2,

WHAT DO CURRENTS TRANSPORT?

​Ocean currents act much like a conveyor belt, transporting warm water and precipitation from the equator toward the poles and cold water from the poles back to the tropics.

​They regulate global climate, helping to counteract the uneven distribution of solar radiation reaching Earth's surface.

​Label The Oceans and the Currents on your Map