Ocean Currents and Prevailing Winds

Ocean Currents and Prevailing Winds

Middle School

​

Learning Objectives

• Describe how uneven heating of the Earth creates wind and ocean currents.

• Explain how winds and continents guide the path of surface ocean currents.

• Analyze how ocean currents move energy and affect a region's climate.

• Differentiate between the causes of surface and deep ocean currents.

Key Vocabulary

​

Ocean Current

The steady, predictable movement of a large body of ocean water in a specific path.

​

Prevailing Winds

These are winds that blow consistently in a single direction over a particular area on Earth.

​

Energy Transfer

This is the natural movement of heat energy from a warmer object or area to a cooler one.

​

Latitude

Latitude measures the distance of any place on Earth north or south from the equator.

​

Temperature

Temperature is the scientific measurement of how hot or how cold an object or place is.

​

Climate

Climate describes the average weather conditions of a specific area over a very long period of time.

Key Vocabulary

​

Coriolis Effect

A force that causes moving fluids like air and water to curve.

​

Density

The measure of how much mass is in a certain volume of a substance.

​

​

Solar Energy and Latitude

• The Sun is Earth’s main energy source, but it heats our planet unevenly.

• The equator gets direct, concentrated sunlight, making these areas much warmer.

• Sunlight hits the poles at an angle, spreading the energy over a larger area.

• This temperature difference creates the wind and ocean currents on our planet.

Multiple Choice

What is the main source of energy for the Earth?

• The Sun's light

• The Earth's core

• Wind and ocean currents

• The Moon's gravity

Multiple Choice

Why are the areas near the equator warmer than the areas near the poles?

• The equator receives more direct sunlight.

• The poles are closer to the Sun.

• The equator has more oceans to hold heat.

• The poles are at a higher altitude.

Multiple Choice

Based on the relationship between solar energy and Earth's systems, what would most likely happen if all parts of the Earth received the same amount of solar energy?

• Wind and ocean currents would be significantly reduced.

• The poles would become warmer than the equator.

• The Earth would stop rotating on its axis.

• The Sun would become much hotter.

​

​

Prevailing Winds and the Atmosphere

How Winds Form

• Prevailing winds are major wind patterns that consistently blow in one direction across our planet.

• They are created by temperature differences between the very hot equator and the cold poles.

• Hot air rises at the equator, travels toward the poles, cools down, and then sinks.

Why Winds Curve

• As our planet rotates, it causes the moving air in the atmosphere to curve.

• This curving of the wind, caused by the Earth's spin, is the Coriolis Effect.

• Winds curve to the right in the Northern Hemisphere and to the left in the Southern.

Multiple Choice

What is the main reason prevailing winds are created?

• The spinning of the Earth on its axis

• Temperature differences between the hot equator and cold poles

• The gravitational pull of the moon

• The movement of ocean currents

Multiple Choice

What causes the path of prevailing winds to curve as they move through the atmosphere?

• The heat from the sun

• The different temperatures at the poles

• The rotation of the Earth

• The path of the moon around the Earth

Multiple Choice

Imagine a large air mass is traveling south from the equator into the Southern Hemisphere. Based on the Coriolis Effect, what would most likely happen to its path?

• It would curve to the right.

• It would curve to the left.

• It would travel in a straight line.

• It would stop moving completely.

​

​

Surface Ocean Currents

• Surface ocean currents are large streams of water on the ocean's surface.

• They are mainly created and driven by the force of prevailing winds.

• Continents act like barriers, blocking and redirecting the flow of water.

• This creates large circular patterns called gyres, like the Gulf Stream.

Multiple Choice

What are surface ocean currents?

• Large streams of water moving on the ocean's surface.

• The rise and fall of sea levels twice a day.

• Deep, cold water rising from the ocean floor.

• Circular patterns of wind in the atmosphere.

Multiple Choice

What is the relationship between strong, prevailing winds and surface ocean currents?

• They are the main force that causes the currents to move.

• They are created by the movement of the currents.

• They block the path of currents and change their direction.

• They have no effect on the movement of ocean currents.

Multiple Choice

If a powerful surface current driven by wind were blocked by a continent, what would be the most likely outcome?

• A large, circular pattern called a gyre would form.

• The current would stop moving completely.

• The wind driving the current would also stop.

• The water would get deeper and flow under the continent.

​

​

Deep Ocean Currents: Driven by Density

• Deep ocean currents are slow-moving streams far below the ocean's surface.

• These currents are driven by changes in water density, not by wind.

• Two factors that change water density are temperature and salinity (saltiness).

• Cold, salty water sinks, driving the global conveyor belt of deep currents.

Multiple Choice

What is the main factor that drives deep ocean currents?

• The density of the water

• The speed of the wind

• The heat from the sun

• The movement of marine animals

Multiple Choice

What combination of factors causes ocean water to become denser and sink?

• Warmer temperature and lower salinity

• Colder temperature and lower salinity

• Warmer temperature and higher salinity

• Colder temperature and higher salinity

Multiple Choice

If a large amount of freshwater from melting glaciers enters a very cold part of the ocean, what is the most likely effect on deep ocean currents in that area?

• The current would speed up because the water is very cold.

• The current might slow down because the water is less salty and therefore less dense.

• The current would not be affected by the change in salinity.

• The current would reverse direction because of the added water.

The Ocean's Impact on Climate

• Ocean currents move heat from the sun around the globe.

• Warm currents from the equator create warmer climates on land.

• Cold currents from the poles result in cooler, drier climates.

Multiple Choice

What is the main way that ocean currents affect the Earth's climate?

• By creating waves that crash onto shorelines.

• By moving heat from the sun around the globe.

• By providing a habitat for marine animals.

• By reflecting sunlight back into space.

Multiple Choice

How does the temperature of an ocean current influence the climate of a nearby coastal region?

• Warm currents create warmer climates, while cold currents create cooler climates.

• Both warm and cold currents make the climate on land wetter.

• Warm currents cause dry weather, and cold currents cause humid weather.

• Ocean currents only affect the temperature of the water, not the land.

Multiple Choice

Imagine a coastal area near the equator that currently has a warm climate. If the ocean current flowing past it were to shift and be replaced by a current flowing from the poles, what would be the most likely effect on the area's climate?

• The area's climate would likely become warmer and more humid.

• The area's climate would not be affected by the change.

• The area's climate would likely become cooler and drier.

• The area would experience less wind and more fog.

​

Common Misconceptions

Misconception	Correction
Oceans only have one type of current.	Oceans have two main types: surface currents and deep ocean currents.
Winds and currents move in straight lines.	The Coriolis Effect curves their paths into large, circular patterns.
All locations at the same latitude have the same climate.	Coastal climates are milder than inland climates at the same latitude.
Climate and weather are the same thing.	Weather is short-term; climate is the long-term average pattern.

​

Summary

• The sun's uneven heating creates winds that drive surface ocean currents.

• Continents redirect currents, creating large circular patterns called gyres.

• Deep ocean currents are driven by changes in water density from temperature and salinity.

• This global system of currents transfers heat and influences regional climates.

Poll

On a scale of 1-4, how confident are you about explaining how oceans influence climate?

• 1 - Not confident at all

• 2 - A little confident

• 3 - Mostly confident

• 4 - Very confident