Ocean Currents: Mass movement or flow of ocean water River within the ocean

 

Two types: Surface and Deep

Surface Current: Horizontal, stream-like movements of water that occur at or near the surface of the ocean. Can reach depths of several hundred meters

 

Surface Currents are Controlled by three factors:

1. Global winds cause surface currents to flow in the direction the wind is blowing.

2. Coriolis Effect: The apparent curving of moving objects due to the Earth’s rotation Northern Hemisphere = clockwise Southern Hemisphere = counter clockwise

3. Continental Deflections: Shape of continents change the direction of current flow

 

Deep Currents: Stream like movement of ocean water far below the surface

Caused by: changes in density: temperature and salinity

Decreasing the temperature of water increases density

Increasing the salinity of water increases density

 

Surface currents and climate Warm water currents

On the east coasts of continents Bring warm water to colder regions

 

Cold water currents On the west coasts of continents

Bring cold water to warmer regions

 

Upwelling: The movement of deep, cold, nutrient rich water to the surface

Nutrients promote growth of fish and plants. Areas are important fishing grounds.

 

Causes of warm and cold currents

El Niño: Change in the water temperature in the Pacific Ocean that produces a warm current

La Niña: Change in the eastern Pacific Ocean in which the surface water temperature becomes unusually cool

Question 1: What is a surface current and what causes them?

Answer: Surface currents move water horizontally – parallel to the Earth’s surface

They are powered by wind

Question 2: What is the Coriolis Effect?

Answer: The Coriolis effect is the shifting of winds and surface currents caused by Earth’s rotation.

 

Question 3: What is upwelling?

Answer: Upwelling is a vertical circulation in the ocean that brings deep, cold water to the ocean surface.