BioEd Online

Teacher Background

We don’t often think about it, but many aspects of life are determined by climate, the characteristics of the weather in a particular region over long periods of time. Climate determines which kinds of plant and animal life are present, which crops can be grown, how people build their houses, and, to a great extent, people’s clothing and diet.

On Earth, there are three major climate zones, determined by distance from the equator. The zone nearest the equator—the tropical zone—is warmest because it receives the most direct radiation from the sun. The zones closest to each pole—the polar zones—are the coldest because they receive the least direct radiation. The broad areas between the tropical and polar zones—known as the temperate zones—generally have snow or rain during cool or very cold winters. The temperate zones lie between 30° and 60° latitude in both hemispheres.

Factors other than latitude also affect climate. Nearness to an ocean usually keeps temperatures cooler in summer and warmer in winter. Altitude also influences temperature; mountainous areas are colder than sea-level regions at the same latitude. In addition, rainfall varies from region to region depending on wind patterns and characteristics of the land. Some parts of the world receive little or no rainfall. Most of these desert areas are located near or within the tropical zone. Other parts of the tropical zone receive large amounts of rain during certain seasons.

Most scientists are concerned that human activities are modifying Earth’s climate. The addition of greenhouse gases, such as carbon dioxide, may lead to increases in global temperatures (global warming). This could cause changes in rainfall and temperature patterns in many parts of the planet, with enormous consequences for ecosystems, cities, and agriculture.

The release of chemicals known as CFCs (chlorofluorocarbons) is also contributing to atmospheric changes that affect climate and human health. Freon and other CFCs are greenhouse gases that contribute to the trapping of heat near Earth’s surface. Chlorine molecules released by these chemicals in the stratosphere break apart the ozone molecules that shield Earth from ultraviolet radiation. Over the last decade, the amount of ozone in the stratosphere has decreased (especially in the polar regions), leading to greater risks of skin cancer for people and also damaging vital populations of plants, animals, and marine life.

This activity is designed to raise students’ awareness of how climate influences all aspects of people’s lives.

Objectives and Standards

Concepts

• Major climate zones are determined by distance from the equator and angle of light received from the sun.

• Rainfall is also an important part of climate.

• Climate affects all aspects of human life.

Science, Health, and Math Skills

• Observing

• Modeling

• Inferring

• Using maps

• Drawing conclusions

Materials and Setup

Teacher Materials (see Setup)

• flashlight

• flashlight batteries

• globe, large inflated balloon, or ball

Materials per Group of Students

• large sheet of paper or poster board

• several sheets of construction paper, asst. colors, 9 in. x 12 in.

• glue sticks or paste

• one or more copies of “Global Climate Map” sheet

Setup

Begin the activity with a whole-class discussion, and then have students work in groups of 4.

Procedure and Extensions

Time

Two 30–minute (or longer) sessions

1. Darken the room and shine a flashlight at the center of a globe (or balloon, or large ball). Ask, If the globe represents Earth and the flashlight represents the sun, which part of Earth receives the most direct light and heat from the sun? Help students understand that the central part of the planet (near the equator) receives light at the most direct angle from the sun. Follow by asking, Which part of Earth do you think might be warmest? Coldest? Why?

2. Distribute copies of the “Global Climate Map” page to each student or group of students. Help students find the equator and relate it to the central portion of the balloon or ball used for your demonstration. Help students identify the polar and temperate regions.

3. Ask, Is temperature the only important part of climate? Lead students to understand that rainfall also is an important part of weather and climate. If students are not familiar with these concepts, introduce them at this point. We use the term “weather” to describe conditions in the atmosphere at a given time or place. We usually measure several variables to describe weather, including temperature, rainfall, wind speed, and humidity. The normal weather in a region over long periods of time is called climate. What is our climate like? Lead a discussion of the climate characteristics in your location (winter conditions, amounts of rainfall, temperatures in summer, etc.).

4. Point out that regions with very little rainfall (deserts) also are shown on the “Global Climate Map” sheet.

5. Assign a climate zone and geographic area from the student page to each group of students. Examples might include a temperate zone of North America, a tropical zone of South America, a tropical desert zone of Africa, and so forth. Give more explicit geographic locations (by country or region) to older students, and have them use outside resources to gather additional information about their assigned regions. Explain that students should think about how people might live in the given climate type. Have each group discuss and decide the types of clothing that people might wear in summer and winter (or during rainy and dry seasons), what the houses might look like, and what foods people might eat. Refer students to the cover of the Global Atmospheric Change unit's Explorations magazine accompanying this unit for ideas. Older students may want to use resources in the library or on the Internet to find additional information.

6. Have each group write a description of the climate in its region and a description of how people live in this region and climate. Have students illustrate their descriptions. Consider having students follow a format such as the one shown below:
   
   Climate Zone
   Geographic Area
   
   Describe:
   The Seasons
   Major Crops
   Major Foods
   Types of Clothes
   Types of Houses
   Other Important Factors

7. Display each group’s descriptions and pictures around the classroom.

Extensions

• The distribution of plants and animals on Earth is determined largely by climate. Have students research and learn about the principal plant and animal communities in their assigned climate zones and regions.

• On a large sheet of paper or poster board, have each group create a “torn paper art” picture of people and houses for their climate. To create “torn paper art,” students should use only pieces of construction paper torn to any size, pasted onto a background. Or, instead of creating torn paper art, have each student group choose the medium for its presentation.

• Have each student group select a city, identify where the city would fall on a map, and conduct research on the climate and lifestyles of people living in that city.

Handouts and Downloads