Global Winds

Global Winds

Middle School

​

Learning Objectives

• Understand that global winds are created by the unequal heating of Earth's atmosphere.

• Describe the three main atmospheric circulation cells: the Hadley, Ferrel, and Polar cells.

• Explain how the Coriolis effect influences the direction of global winds.

• Identify the major global wind belts, including the Trade Winds, Westerlies, and Polar Easterlies.

• Define jet streams and explain how they are formed and affect weather.

Key Vocabulary

​

Global Winds

Planet-wide winds in large belts, caused by the unequal heating of the Earth's atmosphere by the sun.

​

Coriolis Effect

The deflection of moving objects, like wind, caused by the Earth's rotation on its own axis.

​

Trade Winds

Reliable winds near the equator that blow from east to west, historically used by trade ships.

​

Jet Streams

Fast-moving rivers of air high in the troposphere, caused by large temperature differences between air masses.

​

Westerlies

Winds in the middle latitudes that blow from west to east, moving from the subtropics toward the poles.

​

​

Unequal Heating Causes Global Winds

• Global winds are massive, steady streams of air that circle the Earth.

• They are caused by the unequal heating of Earth’s atmosphere by the sun.

• Warm air rises at the equator, creating a low-pressure zone.

• Cooler air sinks elsewhere, creating high-pressure zones that flow to low pressure.

​

Multiple Choice

What is the primary cause of large-scale global winds?

• The movement of ocean currents.

• The rotation of the Earth on its axis.

• The gravitational pull of the moon.

• The unequal heating of the Earth's atmosphere.

​

​

The Coriolis Effect

• Earth's rotation causes the path of winds to curve.

• This curving phenomenon is known as the Coriolis effect.

• Winds in the Northern Hemisphere are deflected to the right.

• In the Southern Hemisphere, winds are deflected to the left.

Multiple Choice

How does the Coriolis effect alter the path of winds in the Northern Hemisphere?

• It deflects them to the right, causing a curved path.

• It deflects them to the left, causing a curved path.

• It causes them to blow in a straight line from north to south.

• It stops the wind from blowing.

Global Wind Belts and Circulation Cells

​

Trade Winds (Hadley Cell)

• These winds are found between 0^o and 30^o latitude.

• They blow from the northeast to the southwest in the Northern Hemisphere.

• Historically, sailors used these reliable winds for trade routes across the ocean.

​

Westerlies (Ferrel Cell)

• These prevailing winds are located between 30^o and 60^o latitude.

• In the Northern Hemisphere, they blow from the southwest toward the poles.

• They are responsible for moving air towards the colder polar regions.

​

Polar Easterlies

• These cold, dense winds are found from 60^o latitude to the poles.

• In the Northern Hemisphere, they travel from the northeast toward the west.

• They are formed as cold air from the poles sinks and moves.

Multiple Choice

Which wind belt is located between 30° and 60° latitude and is driven by the Ferrel Cell?

• The Westerlies

• The Trade Winds

• The Polar Easterlies

• The Doldrums

​

​

Jet Streams and the Polar Front

Jet Streams

• Jet streams are fast-moving 'rivers of air' high up in the atmosphere.

• They are created by big temperature differences between two different air masses.

• The strongest jet streams, called polar jets, are found near the Earth's poles.

The Polar Front

• The Polar Front is a boundary where cold polar air meets warmer air.

• This meeting of air masses often leads to cloudy and unpredictable weather conditions.

• The polar jet stream often forms high above this specific boundary zone.

Multiple Choice

According to the slide, what creates powerful jet streams?

• The Earth's rotation alone.

• The meeting of two circulation cells of the same temperature.

• Large temperature differences between two air masses.

• The calm winds near the equator.

​

Common Misconceptions About Wind

Misconception	Correction
Wind blows in a straight line from north to south.	Earth's rotation causes winds to follow a curved path (the Coriolis effect).
Wind is just a local and short-term weather event.	Global winds are large, long-term systems that circle the planet.
Air sinks at the equator, which causes dry weather.	Warm air rises at the equator, creating a wet, low-pressure zone.

Multiple Choice

Why are regions at the equator, a low-pressure zone, commonly associated with storms and high rainfall?

• Because high-pressure systems dominate the area.

• Because the Coriolis effect is strongest there.

• Because cool, dense air sinks and releases moisture.

• Because warm, moist air rises, cools, and condenses.

Multiple Choice

How do the atmospheric circulation cells, like the Hadley and Polar cells, primarily determine a region's climate?

• By creating local winds that only affect coastal areas.

• By controlling whether air is generally rising (wet climate) or sinking (dry climate).

• By changing the length of days throughout the year.

• By influencing the Earth's magnetic field.

Multiple Choice

If the Earth were to stop rotating, what would be the most significant and immediate impact on the global wind system?

• The winds would blow in straight lines between the equator and the poles.

• The winds would cease to exist entirely.

• The winds would become much stronger and more unpredictable.

• The winds would reverse their primary directions.

Multiple Choice

Based on the global wind patterns, what would be the most effective strategy for a sailing ship trying to travel from Europe to the Caribbean (located near the equator)?

• Stay in the mid-latitudes to use the Westerlies.

• Sail north to use the Polar Easterlies.

• Sail directly west without changing latitude.

• Sail south to the tropics to use the northeast Trade Winds.

​

Summary

• Unequal heating and Earth’s rotation create large, curved wind patterns.

• The three main wind belts are the Trade Winds, Westerlies, and Polar Easterlies.

• Low-pressure systems bring rain, while high-pressure systems bring dry weather.

• Jet streams are fast air currents where different air masses meet.

Poll

On a scale of 1-4, how confident are you about the concepts covered in today's review?

• 1

• 2

• 3

• 4