Earth’s Changing Atmosphere What will make this kite soar? Earth’s atmosphere is a blanket of gases that supports and protects life. Key Concepts SECTION Earth’s atmosphere 1 supports life. Learn about the materials that make up the atmosphere. SECTION The Sun supplies the 2 atmosphere’s energy. Learn how energy from the Sun affects the atmosphere. SECTION Gases in the atmosphere 3 absorb radiation. Learn about the ozone layer and the greenhouse effect. SECTION Human activities affect 4 the atmosphere. Learn about pollution, global warming, and changes in the ozone layer. Prepare and practice for the FCAT • Section Reviews, pp. 616, 623, 627, 635 • Chapter Review, pp. 638–640 • FCAT Practice, p. 641 CLASSZONE.COM • Florida Review: Content Review and FCAT Practice 608 Unit 5: Earth’s Atmosphere How Heavy Is Paper? Put a ruler on a table with one end off the edge. Tap on the ruler lightly and observe what happens. Then cover the ruler with a sheet of paper as shown. Tap again on the ruler and observe what happens. Observe and Think What happened to the ruler when you tapped lightly on it with and without the sheet of paper? Was the paper heavy enough by itself to hold the ruler down? How Does Heating Affect Air? Stretch the lip of a balloon over the neck of a small bottle. Next, fill a bowl with ice water and a second bowl with hot tap water. Place the bottle upright in the hot water. After 5 minutes, move the bottle to the cold water. Observe and Think What changes did you observe in the balloon? What might have caused these changes? Internet Activity: Atmosphere Go to ClassZone.com to learn about Earth’s atmosphere. ClassZone.com Back Forward Reload Home Images Print Security Stop Observe and Think How Location: http://www.classzone.com does the thickness of the atmosphere compare with the height of a mountain or the altitude of the space shuttle in orbit? NSTA scilinks.org Composition of the Atmosphere Code: MDL009 Chapter 17: Earth’s Changing Atmosphere 609 CHAPTER 17 CONCEPT REVIEW VOCABULARY REVIEW •Matter is made up of atoms. mass p. 50 •All things on or near Earth atom p. 56 are pulled toward Earth by molecule p. 58 its gravity. gas p. 68 •Heating or cooling any material changes some of its properties. gravity See Glossary. FLORIDA REVIEW CLASSZONE.COM Content Review and FCAT Practice TAKING NOTES SUPPORTING MAIN IDEAS Make a chart to show The atmosphere makes main ideas and the life on Earth possible. information that supports them. Write each blue heading from the chapter Living things use gases in the air. in a separate box. In boxes below it, add supporting information, such as The atmosphere keeps Earth warm. reasons, explanations, and examples. The atmosphere protects life. VOCABULARY STRATEGY Write each new vocabulary term in the center of a amount of mass frame game diagram. in a given volume Decide what information air higher up is to frame the term with. less dense Use examples, descriptions, pictures, or sentences in DENSITY which the term is used in context. You can change the frame to fit each term. gas has mass same space but more mass = denser 610 Unit 5: Earth’s Atmosphere KEY CONCEPT Earth’s atmosphere supports life. Sunshine State BEFORE, you learned NOW, you will learn STANDARDS •Living things need food, water, • Why the atmosphere is SC.D.1.3.3: The student and air important to living things knows how conditions • Matter can be solid, liquid, • What the atmosphere that exist in one system or gas is made of influence the condi- tions that exist in other • How natural cycles affect systems. the atmosphere SC.D.1.3.4: The student knows the ways in which plants and animals reshape the EXPLORE Air Resistance landscape. SC.G.1.3.4: The student How does air affect falling objects? knows that the interac- tions of organisms with PROCEDURE MATERIALS each other and with • metal washer 1 Drop the washer from shoulder height. the non-living parts of •coffee filter their environments 2 Tape the metal washer to the center of the • tape result in the flow of coffee filter. The filter will act as a parachute. energy and the cycling of matter throughout 3 Drop the washer with the parachute from the system. shoulder height. WHAT DO YOU THINK? • What difference did the parachute make? FCAT VOCABULARY • What do your results tell you about air? atmosphere p. 611 density p. 612 The atmosphere makes life on Earth possible. VOCABULARY altitude p. 612 Every time you breathe in, your lungs fill with air, which is a mixture cycle p. 614 of gases. Your body uses materials from the air to help you stay alive. The atmosphere is a whole layer of air that surrounds Earth. The atmosphere supports life and protects it. The gases of the atmosphere keep Earth warm and transport energy to different regions of the planet. Without the atmosphere, the oceans would not exist, life would not survive, and the planet would be a cold, lifeless rock. Even though the atmosphere is very important to life, it is VOCABULARY surprisingly thin. If the solid part of Earth were the size of a peach, Remember to make a most of the atmosphere would be no thicker than the peach fuzz frame game diagram for surrounding the fruit. The atmosphere is a small but important part the term atmosphere. of the Earth system. check your reading How does the atmosphere make life possible? Find three examples in the text above. Chapter 17: Earth’s Changing Atmosphere 611 Characteristics of the Atmosphere In 1862 two British balloonists reached the highest altitude, or distance above sea level, any human had ever reached. As their balloon rose to 8.8 kilometers (5.5 mi), one balloonist fainted and the other barely managed to bring the balloon back down. They found that the air becomes thinner as altitude increases. The thickness or thinness of air is measured by its density. Density is the amount of mass in a given volume of a substance. If two objects take up the same amount of space, then the object with more mass has a greater density than the one with less mass. For example, a bowling ball has a higher density than a soccer ball. The atmosphere’s density decreases as you travel upward. The air on top of a mountain is less dense than the air at sea level. A deep breath of mountain air fills your lungs but contains less mass—less gas—than a deep breath of air at sea level. Higher up, at altitudes where jets fly, a breath of air would contain only about one-tenth the mass of a breath of air at sea level. The air farther above Earth’s surface INFER This climber has contains even less mass. There is no definite top to the atmosphere. reached the top of Mount It just keeps getting less dense as you get farther from Earth’s surface. Everest, 8850 m (29,000 ft) However, altitudes 500 kilometers (300 mi) or more above Earth’s above sea level in Nepal. Why does he need an surface can be called outer space. oxygen mask? The decrease of density with greater altitude means that most of the mass of the atmosphere is close to Earth’s surface. In fact, more than 99 percent of the atmosphere’s mass is in the lowest 30 kilometers (20 mi). Gas in the Air How do you know that air has different gases? SKILL FOCUS Predicting PROCEDURE 1 Put a spoonful of limewater into each jar. Limewater is clear, but turns milky in the presence of carbon dioxide. 2 Cover one jar. Add extra carbon dioxide to the second jar by exhaling gently into it before you cover it. Tighten the lids carefully to seal the jars. MATERIALS • limewater 3 Predict what will happen, then shake each jar. •2 jars • spoon WHAT DO YOU THINK? TIME •What happened to the limewater in each jar? 10 minutes • How do you know that air is made of different gases? CHALLENGE How would you test a different gas in the air? 612 Unit 5: Earth’s Atmosphere Gases of Earth’s Atmosphere Close to Earth’s surface, nitrogen, oxygen, and other atmospheric Percentages of Gases in Dry Air gases are completely mixed together. A sample of the atmosphere taken argon, from anywhere on Earth would carbon dioxide, oxygen contain about the same percentages and other gases 21% 1% of gases shown in the graph. nitrogen 78% The percentage of water vapor in the atmosphere, not included on this graph, varies from 0% to 4%. INTERPRET How do the graph and the photograph show, in two different ways, that the atmosphere has substance? Materials in the Atmosphere Most of the materials in the atmosphere are gases. However, the atmos- phere also contains tiny particles of solid or liquid material such as dust, sea salt, and water droplets. Perhaps you have sat by an open window and noticed some of these particles on the window sill. If you were to write a recipe for air, you would include nitrogen reading tip gas as the main ingredient. In dry air, about 78 percent of the gas is As you read about the nitrogen. The next most common ingredient is oxygen gas, which amounts of gases, find each gas on the graph above. makes up about 21 percent of the atmosphere. Argon, carbon dioxide, and other gases make up about 1 percent of the atmosphere.