Lesson Harnessing Wind

Learning Objectives

After this lesson, students should be able to:

• Explain the properties of wind.
• Describe some Greek mythology around wind.
• Describe how wind affects humans.
• Explain why wind is a renewable energy source.
• Describe how engineers design technologies to monitor and capitalize on wind energy.

Educational Standards

Each TeachEngineering lesson or activity is correlated to one or more K-12 science, technology, engineering or math (STEM) educational standards.

All 100,000+ K-12 STEM standards covered in TeachEngineering are collected, maintained and packaged by the Achievement Standards Network (ASN), a project of D2L (www.achievementstandards.org).

In the ASN, standards are hierarchically structured: first by source; e.g., by state; within source by type; e.g., science or mathematics; within type by subtype, then by grade, etc.

NGSS: Next Generation Science Standards - Science

International Technology and Engineering Educators Association - Technology

State Standards

Introduction/Motivation

Wind is so important that the Greeks had eight gods and a king of the four winds. The four original and most famous are: Aeolus, the Greek King of the Winds who had four sons; Zephyrus, the God of the West Wind; Boreas, the God of the North Wind; Notus, the God of the Southern Wind; and Eurus, the God of the East Wind.

The Greeks knew that wind had many different characteristics and believed in a god for each one. Can you think of the different characteristics of wind? (Listen to student ideas.) One characteristic is strong winds (Boreas), one is rainy winds (Eurus), one is fog and misty rains (Notus) and another is gentle winds (Zephyrus). People who study wind recognize 32 distinct directions in which winds blow, and you may have noticed 32 divisions marked on compasses.

What exactly is wind? And how does it move? (Listen to student responses.) Basically, wind is just the movement of air. Air generally moves from areas of high to low pressure, creating winds. Wind might be the movement of air on a local scale such as in your neighborhood (local winds) or the movement of air across the entire planet (global winds). Wind can be strong gales and heavy gusts or light breezes. Have you ever been outside when it is really windy? Have you ever seen garbage cans or leaves blown around by the wind? Sometimes the wind is so strong that it blows down buildings and causes damage to structures and landscapes. On the other hand, wind provides us with many benefits, such as cleansing stale valley air, carrying weather balloons high into the atmosphere, generating electricity, and transporting goods and people. We can do fun things with wind, such as fly kites, parasail and hang glide.

Have you seen windmills and wind turbines? Those devices enable us to generate electricity—like the energy we use to heat our homes. Do you think we might ever run out of wind? Wind is considered a renewable energy source because it does not get used up. Students can work as engineers in the activity Gone with the Wind Energy: Design-Build-Test Mini Sail Cars! to explore renewable wind power as they design, construct, test and refine "sail cars"

Engineers work with all aspects of the wind. They design wind turbines that harness wind energy and design better planes to fly through the wind. Students can learn more about windmills with the hands-on design activity Wind Energy: Making & Testing Pinwheels to Model Wind Turbines. Engineers also create devices to monitor and measure wind, such as anemometers and wind vanes, to help predict wind patterns. Refer to the activity Wild Wind! Making Weather Vanes to Find Prevailing Winds to have students build and use their own wind vanes. Using this information, engineers can design better structures to resist the force of heavy winds and advanced warning systems for tornados and hurricanes.

Lesson Background and Concepts for Teachers

Winds are caused by differences in air pressure and temperature. Meteorologists have made enough observations to define areas of high and low pressure across the Earth. For example, along the equator, we usually find low air pressure. In addition, the Sun heats the equator more than any other place on Earth. These factors combined—with the rotation of the Earth (or the Coriolis Effect)—create global winds. Air tends to move towards the equator because air generally moves from areas of high to low pressure, thus creating winds. The winds from the north and south converge at the equator because hot air rises and then cools. The Coriolis Effect diverts air towards the right in the northern hemisphere and towards the left in the southern hemisphere. Without this diversion, air would just sink and return to the equator; but the Coriolis Effect moves it back to the middle latitudes to continue the movement, creating a rotating effect. Similarly, some air from the middle latitudes moves to a low pressure area at the poles.

The global winds just described are named according to where they originate and to where they move. The prevailing westerlies move west to east from the middle latitudes toward the poles between 30 degrees and 60 degrees latitude. The polar easterlies move east to west from the poles to the middle latitudes as the air cools and sinks. The trade winds move from the middle latitudes toward the equator. They are called trade winds because they created an easy route for early explorers' sailboats. The trade winds converge near the equator in area called the doldrums, where the air rises and is characteristic of calm, warm winds..

Winds are also created by local differences in air pressure and temperature, as well as surface disruptions, such as mountains, cliffs and trees. These are measured only on a local scale and last for a few hours or days. Wind blows against the surface of the Earth, and a force called friction slows the wind down. Other obstacles can also affect the wind, including buildings and vehicles.

On hot summer days, many people go to the beach to enjoy the cool breezes, which are usually sea breezes. Sea breezes form when the land mass heats up faster then the ocean during the day so that hot air rises over the land. This in turn creates a low pressure that draws cool air in from the sea, resulting in the pleasant breeze you feel as you walk along the shore. During the night, the opposite happens and land breezes are formed. These breezes are less strong because the temperature and pressure difference are less. Monsoons are similar to land and sea breezes, but they occur over a large scale and change from season to season, rather than day to night. During the summer months in southern Asia, monsoon winds blows from the Indian Ocean and the South China Sea to the land. These monsoons are often accompanied with tremendous rains. During the winter, the wind direction switches and blows from the land to the sea. These winter winds are dry, resulting in clear weather for Southern Asia.

Mountains are surrounded by air at different pressures and temperatures, which often creates imbalances in air pressure and temperature. Mountain regions exhibit many different types of wind: two examples are mountain and valley breezes. Valley breezes occur when the air in valleys becomes heated so that it moves up the mountain slopes. Mountain breezes occur at night when air around the mountain cools and sinks back down the mountain. (As makes sense, mention any unique wind phenomena in your area, such as the Chinook winds in the Rocky Mountain foothills.)

Associated Activities

• Wild Wind! Making Weather Vanes to Find Prevailing Winds - Students learn the difference between global, prevailing, and local winds. They make wind vanes out of paper, straws, and soda bottles and use them to measure wind direction over time. They analyze their data to draw conclusions about the local prevailing winds.

  Watch this activity on YouTube

• Wind Energy: Making & Testing Pinwheels to Model Wind Turbines - Students learn about wind energy by making a pinwheel to model a wind turbine. Just like engineers, they decide where and how their turbine works best by testing it in different areas of the playground.

  Watch this activity on YouTube

• Gone with the Wind Energy: Design-Build-Test Mini Sail Cars! - Students explore the use of wind power in the design, construction and testing of "sail cars," which, in this case, are little wheeled carts with masts and sails that are powered by the moving air generated from a box fan. The scientific method is reviewed and reinforced with the use of controls and variables, and the engineering design process is explored.

  Watch this activity on YouTube

Lesson Closure

Review global and local winds and how air pressure can cause wind as air moves from areas of high to low pressure. Remind students how engineers design ways to harness the wind for energy and technology to predict weather, including the movement and intensity of wind. Discuss how engineers make devices such as wind vanes to measure winds and wind turbines to generate electricity from the wind. Explain that engineers use the information gathered from a wind vane to decide where to locate wind farms or shelter buildings.

Vocabulary/Definitions

air mass: A large area of air defined by common air pressure and temperature.

air pressure: Pressure caused by the weight of the air.

anemometer: A mechanical device that measures wind velocity and force.

Chinook wind: A warm winter wind resulting from mountain terrain and air temperature conditions; occurs in the Rocky Mountain foothills.

climate: Local conditions of a region including wind conditions and temperatures.

Coriolis effect: A global force that causes air to move in a circular motion because of the Earth's rotation.

doldrums: A low-pressure region near the equator whrere prevailing winds are very calm.

equator: The imaginary circle around the Earth's surface that divides the planet into the Northern Hemisphere and the Southern Hemisphere.

land breeze: A breeze that blows from the land toward open water.

monsoon: Wind from the southwest that is accompanied by heavy rain.

polar easterlies: Wind that flows from the north and south poles to the middle latitudes.

prevailing westerlies: Wind that moves west to east from the middle latitudes toward the poles between 30 and 60 degrees latitude.

sea breeze: A cool breeze blowing from the sea toward the land; generally occurs in the early morning.

trade wind: Air current that moves back to the equator.

troposphere: The lowest region of the atmosphere between the Earth's surface and the tropopause, characterized by decreasing temperature with increasing altitude.

Assessment

Pre-Lesson Assessment

Discussion Questions: Solicit, integrate, and summarize student responses.

• What is wind?
• Do you have an interesting story about a windy day?

Post-Introduction Assessment

Question/Answer: Ask students questions and have them raise their hands to respond.

• How many Greek wind gods were there? (Answer: Four gods of the wind and one king of those gods.)
• What is wind? (Answer: It is the movement of air.)
• How can wind be our friend? (Answer: It can produce energy and transport goods and humans. We can do fun things with it, such as fly a kite, parasail and hang glide.)
• What type of energy source is wind? (Answer: Wind is a renewable energy source. This means that wind can generate energy—like the electricity we use to heat our homes—via windmills and wind farms.)
• What does renewable resource mean? (Answer: Renewable resource means that it is resource that we cannot use up; it keeps replenishing itself.)
• What do engineers have to do with wind? (Answer: Engineers design wind turbines to harness energy from the wind. They invent better planes to fly through the wind. Engineers also build devices to monitor and measure wind, such as anemometers and wind vanes, to help predict wind patterns. Using this information, they design better structures to resist the force of heavy winds and advanced warning systems for tornados and hurricanes.)

Lesson Summary Assessment

Sounds of the Wind: Ask students to come up with a sound for each of the four wind gods (north, south, east and west). Then take turns practicing the sounds with the entire class. As you continue your activities and the study of winds, use the sounds to help students remember that wind has many different characteristics.

Toss-a-Fact: Have students stand in a circle of 15 students and toss a ball from person to person across the circle. Start by having the student with the ball say a fact about wind and then toss the ball to someone else. Each time a ball is caught, have the student state a fact about wind or engineers (for example, the doldrums are located near the equator, engineers design ways to generate energy from the wind, wind is a renewable resource, and so on). Continue to toss the ball until you run out of facts. Make it a contest to see how long the group can list facts about the wind.

Lesson Extension Activities

Go on a field trip to a weather station.

Invite an engineer who specializes in airplanes (an aeronautical engineer) to talk about airplanes and how they are designed with wind as a consideration.

References

Copyright

Contributors

Supporting Program

Acknowledgements

The contents of this digital library curriculum were developed under a grant from the Fund for the Improvement of Postsecondary Education (FIPSE), U.S. Department of Education and National Science Foundation GK-12 grant no. 0338326. However, these contents do not necessarily represent the policies of the Department of Education or National Science Foundation, and you should not assume endorsement by the federal government.