Surface Currents (Science Lesson 2.06)

Here are some other factors (besides wind) that can affect the flow and patterns of ocean currents:

-the topography of the sea floor -sea surface height -the shape of the coastline -water temperature

topography

A description of surface features of land.

What is the best description of the motion of surface currents?

At the poles they curve to the left; at the equator, they curve to the right. (The motion of the currents is due to the changes in wind at the surface.)

Earth is actually spinning underneath these convection cells. As a result, the direction of airflow is thrown off its north-south or south-north path. This skewing of wind patterns by the spinning of the planet is called the ?. Large convection cells are broken up into smaller ones. This gives the resulting pattern of Earth's prevailing winds.

Coriolis effect

Prevailing winds

Global winds that blow constantly from the same direction

What is the best description of how the Gulf Stream flows?

It brings warm water from the equator to the coast of northern Europe. (The Gulf Stream is responsible for the palm trees on the English coast.)

How does Earth's rotation affect ocean currents?

It causes them to flow in a curved path. (The Coriolis effect causes currents to flow in a curved path.)

What causes Earth's major wind patterns?

Radiant energy from the sun strikes Earth unevenly. The sun's energy heats air at the equator more than it does at the poles. As a result, air near the equator heats up and rises because it is less dense. As it rises, it cools and begins to flow toward the poles. As this air leaves the equator, cooler and heavier air from the poles flows along the surface to take its place. The result is a series of convection cells with air flowing from the equator to the poles and then turns around and comes back. (Convection is the movement of air due to differences in heat content.)

Coriolis effect

The deflection of winds to the right in the Northern Hemisphere and to the left in the Southern Hemisphere because of Earth's rotation. The Coriolis effect was named for the Frenchman who first described it, Gaspard-Gustave de Coriolis.

How does Earth's rotation affect wind and ocean current patterns?

The rotation of the earth causes the Coriolis effect, which results in wind and ocean currents having a curved shape.

inertia

The tendency of an object to resist a change in motion

What will happen if the wind within the Labrador Current were to stop blowing?

The water would continue to flow because it has inertia. The water would continue to flow for a while because an object in motion will remain in motion.)

What are the main factors that affect an ocean current?

Wind caused by unequal heating of the earth, the Coriolis effect, and geographical features all affect the ocean currents.

Prevailing winds blow most of the time but not all the time. What happens to surface currents when the wind stops blowing? Think about what happens when you push a toy sailboat across the water. The sailboat will keep moving across the water even after you stop pushing. This is because the sailboat has inertia. If an object is already in motion, it will tend to stay in motion. The same is true for ocean water. Even if the wind stops blowing for a little while, the water keeps moving. However, if the wind does not blow for a long time, or if it blows in a different direction for a long time, the currents will eventually ? according to the new situation.

change

convection cells

circular patterns caused by the rising and sinking of air

The Earth's rotation affects ocean currents, causing them to ? as they move between the equator and the poles.

curve

With currents, which are essentially rivers of water within the ocean. Some currents travel along the ocean surface, while others flow in the middle of the ocean or near the ocean floor. Because they carry water from place to place, they also carry ?.

energy

The earth has a number of prevailing wind systems. In any particular place, prevailing winds are those that blow in a certain direction most of the time. If the wind blows ? enough, a surface current begins to flow.

long

To understand surface currents, it is necessary to understand wind patterns. Energy from the sun provides more heat at the equator than at the poles. Because of this, air near the equator warms and rises. As it rises higher and higher, it cools and begins to flow toward the poles. As this warm air moves away from the surface at the equator, cooler, heavier air from the poles moves in to replace it. This results in convection cells moving air between the poles. This all occurs while the planet itself is ?. This causes the lines of moving air to curve clockwise in the north and counterclockwise in the south.

rotating

hot air rises and cool air ?

sinks

In open ocean, surface currents moving from the equator toward the poles tend to veer toward the right, while currents moving from the poles toward the equator veer toward the left. What is this phenomenon called?

the Coriolis effect

Like other surface currents, the Gulf Stream is driven mostly by prevailing winds. When air blows across water, some of it crashes into surface water, pushing and pulling water along. This is one way energy in Earth's atmosphere is ? to the oceans.

transferred

What are prevailing winds?

winds that blow in the same direction (The prevailing winds blow in the same direction at a given location.)