The Four Spheres of the Earth “Extraordinarily complex, extremely diverse, infinitely renewing, and yet ultimately fragile” Tom. L. McKnight
What is Physical Geography? If you think about the world we live in you’ll probably agree that it is roughly divided into (1) things of natural origin, and (2) things of cultural origin (created by people). Natural things are also called physical or environmental. Physical geography is about the physical elements of our world: landforms, soils, rivers, air masses, ecosystems, and so on.
What is Physical Geography? Physical geography asks: How do things differ from place to place? How are things distributed in space? What are the relationships between things?
Key Concepts of the Environment Environment means the surroundings; from the French word “environs”, meaning around. The global environment is an all-inclusive, interacting, and interdependent system. A change in one part of the system has the potential for causing change somewhere else in the system. No event takes place in isolation.
The Global Environment The global environment has four components: the lithosphere, hydrosphere, atmosphere, and biosphere. The interactions of the four spheres are dynamic and constant. An ecosystem is a biological community (i.e. plants and animals) formed by the interaction of living things in a particular environment with one another and with their habitat.
What is the Biosphere? The biosphere is composed of all living organisms (plants, animals, one-celled organisms). Evolved about 3.5 billion years ago Most of the planet’s life is found from 3 meters below the ground to 30 meters above it and in the top 200 meters of the oceans and seas. Includes portions of the hydrosphere, the lithosphere, and the atmosphere.
What is the Hydrosphere? It is all the water in the world. Physical forms Solid Liquid Gas Includes the oceans, rivers, lakes, and even the moisture in the air. 97% of the earth’s water is in the oceans. The remaining 3% is fresh water; ¾ of the fresh water is solid and exists in ice sheets.
What is the Lithosphere? It is the outer layer of the Earth’s crust composed of soil and rocks. This crust is inorganic and is composed of mineral. Can change with movement of plates Earthquakes Mountain-building Volcanoes Continental Drift
What is the Atmosphere? It is the layer of air surrounding the Earth. Primarily nitrogen (79%) and oxygen (21%) A small amount is composed of carbon dioxide. Provides gases for respiration and other gases Protects organisms from UV rays Absorbs energy from the sun and acts as an insulator Ultraviolet light Ultraviolet light Earth