How to Use This Presentation

1. How to Use This Presentation • To View the presentation as a slideshow with effects select “View” on the menu bar and click on “Slide Show.” • To advance through the presentation, click the right-arrow key or the space bar. • From the resources slide, click on any resource to see a presentation for that resource. • From the Chapter menu screen click on any lesson to go directly to that lesson’s presentation. • You may exit the slide show at any time by pressing the Esc key.

2. Resources Chapter Presentation Visual Concepts Transparencies Standardized Test Prep Brain Food Video Quiz

3. Chapter 2 Earth as a System Table of Contents Section 1 Earth: A Unique Planet Section 2 Energy in the Earth System Section 3 Ecology

4. Chapter 2 Section 1 Earth: A Unique Planet Objectives • Describethe size and shape of Earth. • Describethe compositional and structural layers of Earth’s interior. • Identifythe possible source of Earth’s magnetic field. • SummarizeNewton’s law of gravitation.

5. Chapter 2 Section 1 Earth: A Unique Planet Earth Basics • Earth is the third planet from the sun in our solar system. • Earth formed about 4.6 billion years ago and is made mostly of rock. • Approximately 70% of Earth’s surface is covered by a thin layer of water known as the global ocean. • Earth is an oblate sphere, or a slightly flattened sphere. Earth’s pole-to-pole circumference is 40,007 km. Its equatorial circumference is 40,074 km. • Earth’s average diameter is 12,756 km.

6. Chapter 2 Section 1 Earth: A Unique Planet Earth’s Interior • Scientists have made important discoveries about Earth’s interior through studies of seismic waves. • Seismic waves are vibrations that travel through Earth and that are caused by earthquakes and by explosions near Earth’s surface. • By studying seismic waves as they travel through Earth, scientists have determined that Earth is made up of three major compositional zones and five major structural zones.

7. Chapter 2 Section 1 Earth: A Unique Planet Earth’s Interior, continued Compositional Zones of Earth’s Interior • crust the thin and solid outermost layer of Earth that lies above the mantle • Oceanic crust, which lies under the oceans, is only 5 to 10 km thick. The continental crust varies in thickness from 15 km to 80 km. • mantle in Earth science, the layer of rock that lies between Earth’s crust and core • The mantle is nearly 2,900 km thick and makes up almost two-thirds.

8. Chapter 2 Section 1 Earth: A Unique Planet Earth’s Interior, continued Compositional Zones of Earth’s Interior, continued • core the central part of Earth that lies below the mantle • The center of Earth is a sphere composed mainly of nickel and iron whose radius is about 3,500 km.

9. Chapter 2 Section 1 Earth: A Unique Planet Earth’s Interior, continued Reading Check Explain why scientists have to rely on indirect observations to study Earth’s interior.

10. Chapter 2 Section 1 Earth: A Unique Planet Earth’s Interior, continued Reading Check Explain why scientists have to rely on indirect observations to study Earth’s interior. Indirect observations are the only means available for exploring Earth’s interior at depths too great to be reached by drilling.

11. Chapter 2 Section 1 Earth: A Unique Planet Earth’s Interior, continued Structural Zones of Earth’s Interior • The three compositional zones of Earth’s interior are divided into five structural zones. • lithosphere the solid, outer layer of Earth that consists of the crust and the rigid upper part of the mantle • The rigid lithosphere is between 15km and 300 km thick. • asthenosphere the solid, plastic layer of the mantle beneath the lithosphere; made of mantle rock that flows very slowly, which allows tectonic plates to move on top of it • The plastic asthenosphere is about 200 km thick.

12. Chapter 2 Section 1 Earth: A Unique Planet Earth’s Interior, continued Structural Zones of Earth’s Interior, continued • mesosphere literally, the “middle sphere”; the strong, lower part of the mantle between the asthenosphere and the outer core • The mesosphere reaches from the bottom of the asthenosphere to a depth of about 2,900 km. • Below the mesosphere is the liquid outer core. • The outer core surrounds the solid inner core, which begins at a depth of 5,150 km.

13. Chapter 2 Section 1 Earth: A Unique Planet Earth’s Interior, continued The diagram below shows the layers of Earth’s interior.

14. Chapter 2 Section 1 Earth: A Unique Planet Structure of the Earth

15. Chapter 2 Section 1 Earth: A Unique Planet Earth as a Magnet • Earth’s magnetic field extends beyond the atmosphere and affects a region of space called the magnetosphere. • Scientists think that motions within the liquid iron of Earth’s outer core produce electric currents that in turn create Earth’s magnetic field.

16. Chapter 2 Section 1 Earth: A Unique Planet Earth’s Magnetic Field

17. Chapter 2 Section 1 Earth: A Unique Planet Earth’s Gravity • Gravity is the force of attraction that exists between all matter in the universe. • According to Newton’s law of gravitation, the force of attraction between any two objects depends on the masses of the objects and the distance between the objects. • The larger the masses of two objects are and the closer together the objects are, the greater the force of gravity between the objects will be.

18. Chapter 2 Section 1 Earth: A Unique Planet Earth’s Gravity, continued Weight and Mass • Weight is a measure of the strength of the pull of gravity on an object. • An object’s weight depends on its mass and its distance from Earth’s center. Weight and Location • Because the distance between Earth’s surface and its center is greater at the equator than at the poles, the weight of an object at the equator is about 0.3% less than its weight at the North Pole.

19. Section 2 Energy in the Earth System Chapter 2 Objectives • Comparean open system with a closed system. • Listthe characteristics of Earth’s four major spheres. • Identifythe two main sources of energy in the Earth system. • Identifyfour processes in which matter and energy cycle on Earth.

20. Section 2 Energy in the Earth System Chapter 2 Earth-System Science • Some Earth scientists combine knowledge of several fields of Earth science in order to study Earth as a system. • systema set of particles or interacting components considered to be a distinct physical entity for the purpose of study • All systems have boundaries, and many systems have matter and energy that flow though them. • Even though each system can be described separately, all systems are linked. A large and complex system, such as the Earth system, operates as a result of the combination of smaller, interrelated systems.

21. Section 2 Energy in the Earth System Chapter 2 Earth-System Science, continued • The operation of the Earth system is a result of interaction between the two most basic components of the universe: matter and energy. • Matter is anything that has mass and takes up space. • Energy is defined as the ability to do work. Energy can be transferred in a variety of forms, including heat, light, vibrations, or electromagnetic waves. • A system can be described by the way that matter and energy are transferred within the system or to and from other systems.

22. Section 2 Energy in the Earth System Chapter 2 Earth-System Science, continued Closed Systems • A closed system is a system in which energy, but not matter is exchanged with the surroundings. Open Systems • An open system is a system in which both energy and matter are exchanged with the surroundings.

23. Section 2 Energy in the Earth System Chapter 2 Earth-System Science, continued The figure below compares open and closed systems.

24. Section 2 Energy in the Earth System Chapter 2 Earth-System Science, continued The Earth System • Technically, all systems that make up the Earth system are open. • However, the Earth system is almost a closed system because matter exchange is limited. • Energy enters the system in the form of sunlight and is released into space as heat. • Only a small amount of dust and rock from space enters the system, and only a fraction of the hydrogen atoms in the atmosphere escape into space.

25. Section 2 Energy in the Earth System Chapter 2 Earth-System Science, continued Reading Check What types of matter and energy are exchanged between Earth and space?

26. Section 2 Energy in the Earth System Chapter 2 Earth-System Science, continued Reading Check What types of matter and energy are exchanged between Earth and space? Dust and rock come to Earth from space, while hydrogen atoms from the atmosphere enter space from Earth. Solar energy enters Earth’s atmosphere and reradiated energy leaves Earth.

27. Section 2 Energy in the Earth System Chapter 2 Earth’s Four Spheres • Matter on Earth is in solid, liquid, and gaseous states. The Earth system is composed of four “spheres” that are storehouses of all of the planet’s matter. The Atmosphere • atmospherea mixture of gases that surrounds a planet or moon • The atmosphere provides the air you breathe and shields Earth from the sun’s harmful radiation.

28. Section 2 Energy in the Earth System Chapter 2 Earth’s Four Spheres, continued The Hydrosphere • hydrospherethe portion of Earth that is water • Water covers 71% of Earth’s surface. • Water in the hydrosphere occur in the form of oceans, lakes, rivers, streams, glaciers and ice sheets, and groundwater.

29. Section 2 Energy in the Earth System Chapter 2 Earth’s Four Spheres, continued The Geosphere • geospherethe mostly solid, rocky part of Earth; extends from the center of the core to the surface of the crust • The geosphere includes all of the rock and soil on the surface of the continents and on the ocean floor. • The geosphere also includes the solid and molten interior of Earth.

30. Section 2 Energy in the Earth System Chapter 2 Earth’s Four Spheres, continued The Biosphere • biospherethe part of Earth where life exists; includes all of the living organisms on Earth • The biosphere is composed of all of the forms of life in the geosphere, in the hydrosphere, and in the atmosphere, as well as any organic matter that has not decomposed. • The biosphere extends from the deepest parts of the ocean to the atmosphere a few kilometers above Earth’s surface.

31. Section 2 Energy in the Earth System Chapter 2 Earth’s Energy Budget • The transfers of energy between Earth’s spheres can be thought of as parts of an energy budget. • The first law of thermodynamics states that energy is transferred between systems, but it cannot be created or destroyed. • The second law of thermodynamics states that when energy transfer occurs, matter becomes less organized with time. Thus, the universe’s energy is spread out more uniformly over time. • The constant exchange of matter and energy between Earth’s spheres happens through chemical reactions, radioactive decay, the radiation of energy ,and the growth and decay of organisms.

32. Section 2 Energy in the Earth System Chapter 2 Earth’s Energy Budget, continued The figure below shows Earth’s energy budget.

33. Section 2 Energy in the Earth System Chapter 2 Earth’s Energy Budget, continued Reading Check Define energy budget.

34. Section 2 Energy in the Earth System Chapter 2 Earth’s Energy Budget, continued Reading Check Define energy budget. An energy budget is the total distribution of energy to, from, and between Earth’s various spheres.

35. Section 2 Energy in the Earth System Chapter 2 Earth’s Energy Budget, continued Internal Sources of Energy • When Earth formed about 4.6 billion years ago, its interior was heated by radioactive decay and gravitational contraction. • The decay of radioactive atoms still generates enough heat to keep Earth’s interior hot. Earth’ interior also retains much of the energy from the planet’s formation. • By the process of convection, the heat in Earth’s interior is transferred through the layers of Earth and is released at Earth’s surface.

36. Section 2 Energy in the Earth System Chapter 2 Earth’s Energy Budget, continued External Energy Sources • Earth’s most important external energy source is the sun. • Solar radiation warms Earth’s atmosphere and surface. This heating causes the movement of air masses, which generates winds and ocean currents. Many chemical reactions on Earth also require solar energy. • Another important external source of energy is gravitational energy from the moon and sun. This energy helps generate tides that cause currents and drive the mixing of ocean water.

37. Section 2 Energy in the Earth System Chapter 2 Cycles in the Earth System • A cycle is a group of processes in which matter and energy repeatedly move through a series of reservoirs. • A reservoir is a place where matter or energy is stored. • Many elements on Earth cycle between reservoirs. These cycles rely on energy sources to drive them. • The length of time that energy or matter spends in a reservoir can vary from a few hours to several million years.

38. Section 2 Energy in the Earth System Chapter 2 Biogeochemical Cycle

39. Section 2 Energy in the Earth System Chapter 2 Cycles in the Earth System, continued The Nitrogen Cycle • In the nitrogen cycle, nitrogen moves from the air to soil, from soil to plants and animals, and back to air again. • Nitrogen is removed from air mainly by the action of nitrogen-fixing bacteria in the soil. • The nitrogen enters plants, which are eaten by animals. The nitrogen is returned to the soil by decay and by animal wastes. • Chemical processes that occur in the soil then release the nitrogen back into the air.

40. Section 2 Energy in the Earth System Chapter 2 Cycles in the Earth System, continued The figure below illustrates the nitrogen cycle.

41. Section 2 Energy in the Earth System Chapter 2 Cycles in the Earth System, continued Reading Check Identify two nitrogen reservoirs on Earth.

42. Section 2 Energy in the Earth System Chapter 2 Cycles in the Earth System, continued Reading Check Identify two nitrogen reservoirs on Earth. Answers should include two of the following: the atmosphere, animals, soil, and plants.

43. Section 2 Energy in the Earth System Chapter 2 Cycles in the Earth System, continued The Carbon Cycle • Carbon moves through all four spheres through the carbon cycle. • In the short-term carbon cycle, plants convert carbon dioxide, CO2, from the atmosphere into carbohydrates. When organisms’ bodies break down the carbohydrates and release some of the carbon back into the air as CO2 or through their organic wastes as CO2 or methane, CH4. • In the long-term carbon cycle, carbon is stored in the geosphere in a type of rock called a carbonate.

44. Section 2 Energy in the Earth System Chapter 2 Cycles in the Earth System, continued The figure below illustrates the carbon cycle.

45. Section 2 Energy in the Earth System Chapter 2 Cycles in the Earth System, continued The Phosphorus Cycle • During the phosphorus cycle, phosphorus moves through every sphere except the atmosphere. • Phosphorus enters soil and water when rock breaks down, when phosphorus in rock dissolves in water, or when organisms excrete phosphorus in their waste. • Plants absorb phosphorus through their roots and incorporate the phosphorus into their tissues. • Animals absorb the phosphorus when they eat the plants. When the animals die, the phosphorus returns to the environment through decomposition.

46. Section 2 Energy in the Earth System Chapter 2 Cycles in the Earth System, continued The Water Cycle • The movement of water from the atmosphere to Earth’s surface and back to the atmosphere is called the water cycle. • In the water cycle, water changes from liquid water to water vapor through the energy transfers involved in evaporation and transpiration. During these processes, water absorbs heat and changes into a gaseous state. • When the water loses energy, it condenses to form water droplets, such as those that form clouds and fall to Earth’s surface as precipitation.

47. Section 2 Energy in the Earth System Chapter 2 Humans and the Earth System • All natural cycles can be altered by human activities. • The carbon cycle is affected when humans use fossil fuels. • The nitrogen and phosphorus cycles are affected by agriculture. • Humans must be careful to moderate their influences on natural systems.

48. Chapter 2 Section 3 Ecology Objectives • Defineecosystem. • Identifythree factors that control the balance of an ecosystem. • Summarizehow energy is transferred through an ecosystem. • Describeone way that ecosystems respond to environmental change.

49. Chapter 2 Section 3 Ecology Ecosystems • Ecology is the study of the complex relationships between living things and their nonliving, or abiotic environment. • ecosystem a community of organisms and their abiotic environment • An ecosystem may be as large as an ocean or as small as a rotting log. The largest ecosystem is the entire biosphere.

50. Chapter 2 Section 3 Ecology Ecosystems, continued • Organisms that make their own food are called producers. Most producers use energy from the sun to produce their own food. • Consumers are organisms that get their energy by eating other organisms. Consumers may get energy by eating producers or by eating other consumers. • Some consumers get energy by breaking down dead organisms. These consumers are called decomposers. • To remain healthy, an ecosystem needs to have a balance of producers, consumers, and decomposers.