Chapter: The Atmosphere in Motion

2. Table of Contents Chapter: The Atmosphere in Motion Section 1: The Atmosphere Section 2: Earth’s Weather Section 3: Air Masses and Fronts

3. The Atmosphere 1 A. Investigating Air 1. Galileo Galilei (1564-1642), an Italian astronomer and physicist, suspected that air was more than just empty space. 2. He weighed a flask, then injected air into it and weighed it again. 3. Galileo observed that the flask weighed more after injecting the air.

4. The Atmosphere 1 A. Investigating Air 4. He concluded that air must have weight and therefore must contain matter. • 5. Today scientists know that air stores and releases heat and holds moisture. Because it has weight, air can exert pressure.

5. The Atmosphere 1 B. Composition of the Atmosphere 1. The atmosphere—the layer of gases surrounding Earth—provides Earth with all the gases necessary to support life. 2. Because it is composed of matter and has mass, the atmosphere is subject to the pull of gravity. 3. The atmosphere is composed of a mixture of gases, liquid water, and microscopic particles of solids and other liquids.

6. The Atmosphere 1 C. Gases • This graph shows the gases found in the atmosphere. 1. Nitrogen (N2) makes up about 78 percent of the atmosphere. 2. Oxygen (O2), the gas necessary for human life, makes up about 21 percent. Two of the trace gases have important roles within the atmosphere.

7. The Atmosphere 1 C. Gases 3. Water vapor (H2O) makes up from 0.0 to 4.0 percent of the atmosphere and is critical to weather. 4. Carbon dioxide is needed for plants to make food. It also absorbs heat and helps keep Earth warm.

8. The Atmosphere 1 D. Aerosols • Solids such as dust, salt, and pollen and tiny liquid droplets such as acids in the atmosphere are called aerosols (AR uh sahlz). • Salt enters the atmosphere when wind blows across the oceans.

9. The Atmosphere 1 D. Aerosols 3. Pollen enters the atmosphere when it is released by plants. 4. Volcanoes add many aerosols to the atmosphere. 5. Human activities also release aerosols into the air.

10. The Atmosphere 1 F. Layers of the Atmosphere 1. The atmosphere is divided into layers based on temperature changes that occur with altitude. 2. The white temperature scale shows temperatures in the thermosphere and exosphere.

12. The Atmosphere 1 G. Troposphere 1. The troposphere (TROH puh sfihr) is the atmospheric layer closest to Earth’s surface. It extends upward to about 10 km. 2. The troposphere contains about three-fourths of the matter in Earth’s entire atmosphere and nearly all of its clouds and weather.

13. The Atmosphere 1 G. Troposphere 3. About 50 percent of the Sun’s energy passes through the troposphere and reaches Earth’s surface. 4. Temperatures in the troposphere are usually warmest near the surface and tend to cool as altitude increases.

14. The Atmosphere 1 H. Stratosphere 1. The stratosphere extends from about 10 km to about 50 km above Earth’s surface. 2. Most atmospheric ozone is contained in the stratosphere. 3. Without the ozone in this layer, too much radiation would reach Earth’s surface, causing health problems for plants and animals.

15. The Atmosphere 1 I. Upper Layers 1. Above the stratosphere is the mesosphere (ME zuh sfihr). 2. This layer extends from approximately 50 km to 85 km above Earth’s surface.

16. The Atmosphere 1 I. Upper Layers 3. The thermosphere (THUR muh sfihr) is above the mesosphere. 4. Temperatures increase rapidly in this layer to more than 1700°C. (3092°F) 5. The thermosphere layer filters out harmful X rays and gamma rays from the Sun.

17. The Atmosphere 1 I. Upper Layers 6. A part of the thermosphere and mesosphere is called the ionosphere (i AH nuh sfihr). 7. This layer of ions is useful because it can reflect AM radio waves making long distance communication possible.

18. The Atmosphere 1 I. Upper Layers 8. The outermost layer of the atmosphere is the exosphere. 9. It extends outward to where space begins and contains few atoms. 10. No clear boundary separates the exosphere form space.

19. The Atmosphere 1 J. Earth’s Water 1. Earth’s surface is about 70 percent water. 2. Water can exist in three separate states – ice, water and water vapor. 3. Water is found as solid snow and ice in glacier. In oceans, lakes and rivers water exists as a liquid and in the atmosphere it exists as gaseous vapor.

20. The Atmosphere 1 K. The Water Cycle 1. Earth’s water is in constant motion. the water cycle is the never-ending cycle of water between Earth’s surface and the atmosphere.

21. The Atmosphere 1 K. The Water Cycle 2. Water on Earth’s surface—in oceans, lakes, rivers, and streams—absorbs energy and stores it as heat.

22. The Atmosphere 1 K. The Water Cycle 3. When water has enough heat energy, it changes from liquid water into water vapor in a process called evaporation.

23. The Atmosphere 1 K. The Water Cycle 4. Water vapor then enters the atmosphere. 5. Evaporation occurs from all bodies of water, no matter how large or small.

24. The Atmosphere 1 K. The Water Cycle 6. Water also is transferred into the atmosphere from plant leaves in a process called transpiration.

25. The Atmosphere 1 K. The Water Cycle 7. Eventually, the water molecules change back into droplets of liquid water. This process is called condensation.

26. The Atmosphere 1 K. The Water Cycle 8. Eventually, these droplets become large enough to be visible, forming a cloud. 9. If the water droplets continue to get larger, they become too large and heavy to remain in the atmosphere and fall to Earth as precipitation.

27. The Atmosphere 1 K. The Water Cycle 10. After the water is on the ground, some of it evaporates. 11. Most water enters streams or soaks into the soil. In the soil, it is called groundwater. 12. Much of this water makes its way back to lakes or to the oceans, where more evaporation occurs and the water cycle continues.

28. Section Check 1 Question 1 Identify the layers of the atmosphere and briefly explain their characteristics.

29. Section Check 1 Question 2 How does an erupting volcano affect Earth’s atmosphere?

30. Section Check 1 Question 3 What is the process called when water changes from a liquid into a vapor? A. condensation B. evaporation C. precipitation D. transpiration

31. Section Check 1 Q 1 Answer Troposphere: weather occurs in this layer; Stratosphere: contains atmospheric ozone, absorbs ultraviolet radiation from the Sun; Mesosphere: contains little ozone and therefore absorbs very little radiation; Thermosphere: filters out harmful X-rays and gamma rays from the Sun; Ionosphere: reflects AM radio waves making long-distance communication possible; Exosphere: extends into space

32. Section Check 1 Q 2 Answer When a volcano erupts, it releases tiny particles of ash or aerosols into the atmosphere. This ash creates a blanket over Earth’s surface that reflects solar energy and influences weather and climate.

33. Section Check 1 Q 3 Answer The answer is B. Evaporation occurs when water has enough heat energy to change from a liquid into water vapor

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35. End of Chapter Summary File