Waves and Currents

Waves and

Currents

Open Ended

What do you think a wave is? If you don't know, tell me what you do know about waves or how they work

Waves

A wave is a rhythmic

movement that
carries energy

through matter and
space. In the ocean,
waves move through

seawater.

Causes of Waves

⚫When wind blows across a body of water,

wind energy is transferred to the water

⚫If the wind speed is great enough, the water

begins to pile up, forming a wave

⚫The height of a wave depends on:

⚫The speed of the wind

⚫The distance over which the wind blows

⚫The length of time the wind blows

Multiple Choice

What causes waves to form?

• Wind

• Rain

• Gravity

Multiple Choice

What does the wind transfer to the water to form a wave?

• Energy

• More water

• Heat

Causes of Waves

⚫ Once set in motion, waves continue moving for

long distances, even if the wind stops blowing

⚫ The waves you see lapping at a beach could have

formed halfway around the world

Ocean
Currents

Ocean Currents

Ocean currents are a mass flow of

ocean water.

There are two main types of currents

we will be discussing: Surface
Currents and Density Currents

Ocean Currents:
Surface Currents

⚫Surface currents move water horizontally – parallel

to Earth’s surface

⚫Surface currents are powered by wind
⚫The wind forces the ocean to move in huge, circular patterns

⚫There are warm surface currents and cold surface

currents

Ocean Currents:
Surface Currents

Open Ended

What do you think would happen to a country that was surrounded by cold surface currents? Would the country be warm or cold?

Surface Currents Affect Climate

⚫ The ocean absorbs, stores, and moves the sun’s

heat (energy)

⚫ Surface currents transport this energy all over the

world

⚫ Surface currents move warmer water into cooler

regions and return cooler water to the warmer
regions (tropics)

⚫ Currents can have a cooling effect on an area’s

climate or a warming effect on an area’s climate

⚫ As warm water flows from the equator, heat is

released into the atmosphere and the air is warmed.

Surface Currents

Notice again the Red arrows and the Blue arrows showing the
movement of warm water and the movement of cold water

Ocean Currents:
Surface Currents

⚫ Surface winds and surface currents are affected

by the rotation of the Earth (the Coriolis Effect)

⚫ Because Earth rotates toward the east, winds

appear to curve to the right in the northern
hemisphere and to the left in the southern
hemisphere

⚫ So, currents north of the equator turn to the right

and currents south of the equator turn to the left

Multiple Select

Density Refresher! What two things can change something's density?

• Mass

• Volume

• Height

• Gravity

Multiple Choice

How can a change in temperature change something's density?

• It changes the volume

• It changes the mass

Different densities are responsible for
ocean currents. What factors did we

learn influence ocean water’s density?

Temperature and Salinity Affect the

Density

of Ocean Water.

Density Currents

⚫ Deep in the ocean, waters circulate not because

of wind but because of density differences.

⚫ A density current forms when a mass of

seawater becomes more dense than the
surrounding water.

⚫ More dense seawater sinks beneath less dense

seawater.

⚫ Density currents circulate ocean water slowly.

Density Currents

Density Currents