Earth's Spheres

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Slide 1: 

The Earth System Connections among the great spheres

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Our Home Planet A closed system ! Has well-defined continents and ocean basins Only planet presently known to support life About 4.5 billion years old Very dynamic, both internally and externally

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Earth As A Closed System Closed system: exchange of energy but negligible exchange of mass with surroundings Mass conserved within system (no gain or loss)

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Four Spheres Within Closed System Within this closed system are four major, interlinked components: Geosphere Hydrosphere Atmosphere Biosphere Energy and matter are exchanged between these components.

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Why can Earth sustain life ? Not too close or far from Sun, thus preventing life from freezing or frying Large enough to hold atmosphere Abundance of water Temperature range to allow water to exist in liquid (very important) as well as gaseous, and solid forms. The interaction of the four components or “spheres” of the Earth system. Distance from the sun, Atmosphere, water

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Earth’s Four Spheres

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Geosphere Geosphere: The solid, inorganic Earth, including Earth’s surface and layers of its interior. The Earth is composed of nested shells that are classified according to their chemical and mechanical characteristics.

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crust mantle core lithosphere asthenosphere mesosphere outer core inner core Composition Mechanical Characteristics liquid solid solid brittle solid solid (but nearly liquid) Earth’s Layers: Composition and Mechanical Characteristics Primarily iron and nickel Primarily silica plus iron and magnesium Primarily silica plus light metallic elements

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Lithosphere contains both crust and uppermost (brittle) layer of mantle Geosphere: Chemical and Mechanical Characteristics Combined

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Some important roles of the Geosphere: Contributor of particulate matter (e.g. volcanic ash) to atmosphere. Ultimate contributor of salts to the ocean (due to ions being released from weathered rock). Ultimate source of nutrients for all living things. Important contributor of atmospheric gases (from volcanoes) Movement of plates produces barriers that aid in the isolation of population of organisms (and therefore influences evolution).

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The Dynamic Geosphere Processes that occur beneath Earth’s surface are manifest in earthquakes and volcanism. These phenomena are linked to the movement of tectonic plates that, in turn, is driven by internal Earth processes. Earthquakes Plate Boundaries Volcanoes

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97 percent of the earth's water is in the oceans. The remaining 3 percent is fresh water (mostly in ice sheets, but also in the air as vapor, and below Earth’s surface as groundwater). The presence of liquid surface water makes our planet unique. Surface temperatures of oceans (blue= coldest red= warmest) Hydrosphere:The hydrosphere is composed of all of the water in the Earth system, including water in the oceans, rivers, lakes, air, and below Earth’s surface. Hydrosphere

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Hydrosphere Some important roles of the hydrosphere: Moderates climate Transfers heat Organisms need water to transport nutrients and waste Water is essential in many of Earth’s processes, from mineral formation to the weathering and erosion of rock. The hydrosphere controls temperature and transportation

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The Cryosphere is part of the hydrosphere. The cryosphere is on Earth’s surface where water is in solid form, including sea ice, lake ice, river ice, snow cover, glaciers, ice caps, ice sheets, and frozen ground (which includes permafrost)

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Most of our atmosphere is located close to the earth's surface where it is most dense. The air of our planet is 79% nitrogen and just under 21% oxygen; the small amount remaining is composed of carbon dioxide and other gases. Atmosphere: The atmosphere is the body of gases that surrounds our planet. Atmosphere

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Some important roles of the atmosphere: Contains the gases that living things need for survival (e.g., carbon dioxide for photosynthesis, and oxygen for aerobic respiration). Transfers heat. Ozone in stratosphere protects living things from excess ultraviolet radiation. Plays a part in weathering and erosion. Atmosphere

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Biosphere Most of Earth’s life is found from about 3 meters below the ground to 30 meters above it and in the top 200 meters of the oceans and seas. Biosphere: The sphere that includes all living organisms. Plants, animals, and microbes are all part of the biosphere. It also includes organic matter not yet decomposed. But…life can thrive in the most unlikely places, from hot springs to ice caps.

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Some important roles of the biosphere: Aids in weathering (e.g. formation of acids in soil). An important step for certain elements (especially carbon). Helps the formation of some minerals. Photosynthesis maintains the oxygen content of the atmosphere. Biosphere I’m starting to understand how all the spheres are related!

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A Recent Addition to Biosphere: Human Activity The presence of humans and the extent of human influence can be appreciated by looking at satellite photos. Even at night, evidence of human activity can be seen. White dots: major centers of human population Yellow patches: fires from slash-and-burn farming Red patches: natural gas burning in major oil fields

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Interconnectedness of Spheres To appreciate how strongly interconnected the Earth’s spheres really are, we need only to think about what happens to substances within the system. For example, the carbon cycle. At any given point in time, carbon occurs in all of the great spheres.

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Earth’s Spin and Tilt Earth is not just a static lump of rock ! As it spins on its tilted axis, different areas of Earth are exposed to different amounts or intensities of the Sun’s energy. This gives us seasons.

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Considering Interactions Between the Spheres Identify some interactions that are represented in this picture.

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What interactions are in this picture?

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What interactions are in this image?

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A forest fire is another small example of how Earth’s spheres interact.

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Interactions Between Spheres: Cause and Effect Initial Conditions Geosphere: The ground could have been very permeable, preventing moisture from being retained in the upper part of the soil profile. Hydrosphere: The area could have been prone to fire due to lack of precipitation. Atmosphere: The fire could have started due to a lightning strike. Biosphere: Dead wood, leaves and needles may have enhanced the ability of the fire to start and spread. Each of the spheres added to the conditions necessary for a fire.

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How the fire impacts the Geosphere Heat from the fire causes rocks to crack (therefore enhancing weathering). Soil erosion is also enhanced by the removal of vegetation. Ash particles from the fire change the chemistry of the soil.

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How the fire impacts the Atmosphere Smoke and ash particles are carried by wind to other areas. Increased precipitation elsewhere is enhanced due to the ash particles acting as nucleation centers for water droplets. Gaseous pollutants such as carbon dioxide (CO2) are produced during the burning of the vegetation and carried into the air by the wind.

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How the fire impacts the Hydrosphere Heat from the fire further removes moisture from the air, soil, and vegetation through the process of evaporation. Increased silt in streams due to enhanced erosion (particles are then deposited as sediment).

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How the fire impacts the Biosphere (part 1) Immediate destruction of habitat in burn area. Smoke in the air may have coats the lungs of animals, including people, and affects their ability to breathe. Ash particles in water clogs the gills of fish and other aquatic organisms.

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4. On the positive side, nutrients released from ash from the fire can, on the long term, benefit future plant communities. 5. Also, seeds of some plants may require that their outer shells be burned before they can germinate (so the forest fire benefits these plants). How the fire impacts the Biosphere (part 2)

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Examples of events that may have something to do with interactions between components of the Earth system: Initiation of ice ages Mass extinctions Global climate change El Nino events. Interactions in the Earth’s spheres can impact the entire globe.

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Everything that happens in the biosphere is dependent on what is happening in the geosphere, hydrosphere, and atmosphere. The Bottom Line

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