THE SPHERES OF EARTH

Lesson: The Four Spheres of Earth

 

Section 1: Definitions and Diagrams

The Earth is a complex system made up of different components that interact with one another. These components are organized into four "spheres"—the Hydrosphere, Geosphere, Atmosphere, and Biosphere. Let's take a closer look at each of these spheres.

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1. The Hydrosphere

• Definition: The hydrosphere refers to all the water on Earth. This includes oceans, rivers, lakes, glaciers, underground water, and water vapor in the atmosphere.

• Key Points:

  • Covers about 71% of Earth's surface.

  • Includes saltwater (oceans) and freshwater (rivers, lakes, groundwater).

  • The water cycle (evaporation, condensation, precipitation) is a key process in the hydrosphere.

• Diagram of the Hydrosphere:

  • A large body of water like an ocean with rivers flowing into it, clouds forming above, and ice caps at the poles.

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2. The Geosphere

• Definition: The geosphere is the solid, rocky part of Earth, including the crust, mantle, and core.

• Key Points:

  • The geosphere consists of the landforms on Earth's surface (mountains, valleys, plains) and the layers beneath the Earth's surface.

  • The movement of tectonic plates (causing earthquakes and volcanic activity) is a key part of the geosphere.

• Diagram of the Geosphere:

  • Earth’s layers, showing the crust, mantle, outer core, and inner core.

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3. The Atmosphere

• Definition: The atmosphere is the layer of gases surrounding Earth. It contains air and is essential for life, providing oxygen and protecting us from harmful solar radiation.

• Key Points:

  • Composed mainly of nitrogen (78%) and oxygen (21%), with trace gases like carbon dioxide and argon.

  • The atmosphere has several layers: troposphere (weather happens here), stratosphere, mesosphere, and thermosphere.

• Diagram of the Atmosphere:

  • A layered structure surrounding the Earth, with arrows indicating weather patterns like clouds and winds.

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4. The Biosphere

• Definition: The biosphere refers to all living organisms on Earth, from microscopic bacteria to large mammals and plants.

• Key Points:

  • The biosphere includes all ecosystems: forests, oceans, deserts, and the atmosphere.

  • Life on Earth exists in both the land and the water, and interactions between organisms are fundamental to the biosphere.

• Diagram of the Biosphere:

  • Representation of animals, plants, and microorganisms, including those in land (forests, grasslands) and water (oceans, rivers).

 

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