Global Atmospheric Change
People and Climate
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.
There are three major climate zones on the planet, 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) also is 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. In addition, 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.
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?
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.
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. Ask, What is our climate like? Lead a discussion of the climate characteristics in your location (winter conditions, amounts of rainfall, temperatures in summer, etc.).
Keywords: atmosphere | carbon cycle | carbon monoxide | climate | CO2 | combustion | Earth | ecology | energy | environment | fossil fuel | global change | greenhouse gas | heat | life science | ozone | physical science | pollution | radiation | skin | skin damage | solar energy | sun | temperature | UV light | weather | lesson
- Illustration © Baylor College of Medicine\M.S. Young.
- Moreno, N., Tharp, B., and Dresden, J. (2011) The Science of Global Atmospheric Change Teacher’s Guide. Baylor College of Medicine: Houston. ISBN: 978-1-888997-75-0.
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Funded by the following grant(s)
My Health My World: National Dissemination
Grant Number: 5R25ES009259
The Environment as a Context for Opportunities in Schools
Grant Number: 5R25ES010698, R25ES06932
Foundations for the Future: Capitalizing on Technology to Promote Equity, Access and Quality in Elementary Science Education