The Four Spheres of the Earth

“Extraordinarily complex, extremely diverse, infinitely renewing, and yet ultimately fragile” Tom. L. McKnight

What is Physical Geography?What is Physical Geography?

If you think about the world we live in you’ll If you think about the world we live in you’ll probably agree that it is roughly divided into probably agree that it is roughly divided into (1) things of natural origin, and (2) things of (1) things of natural origin, and (2) things of cultural origin (created by people). Natural cultural origin (created by people). Natural things are also called physical or things are also called physical or environmental.environmental.

Physical geography is about the physical Physical geography is about the physical elements of our world: landforms, soils, rivers, elements of our world: landforms, soils, rivers, air masses, ecosystems, and so on.air masses, ecosystems, and so on.

What is Physical Geography?What is Physical Geography?

Physical geography asks: Physical geography asks: How do things differ from place to place?How do things differ from place to place? How are things distributed in space?How are things distributed in space? What are the relationships between things?What are the relationships between things?

Key Concepts of the EnvironmentKey Concepts of the Environment

Environment means the Environment means the surroundingssurroundings; from ; from the French word “the French word “environsenvirons”, meaning ”, meaning aroundaround..

The global environment is an all-inclusive, The global environment is an all-inclusive, interacting, and interdependent system. A interacting, and interdependent system. A change in one part of the system has the change in one part of the system has the potential for causing change somewhere else potential for causing change somewhere else in the system. No event takes place in in the system. No event takes place in isolation.isolation.

The Global EnvironmentThe Global Environment

The global environment has four components: The global environment has four components: the the lithospherelithosphere, , hydrospherehydrosphere, , atmosphereatmosphere, , and and biospherebiosphere..

The interactions of the four spheres are The interactions of the four spheres are dynamic and constant.dynamic and constant.

An An ecosystemecosystem is a biological community (i.e. is a biological community (i.e. plants and animals) formed by the interaction plants and animals) formed by the interaction of living things in a particular environment of living things in a particular environment with one another and with their habitat.with one another and with their habitat.

WhatWhat is the Biosphere? is the Biosphere?

The biosphere is composed of all living organisms The biosphere is composed of all living organisms (plants, animals, one-celled organisms).(plants, animals, one-celled organisms).

Evolved about 3.5 billion years agoEvolved about 3.5 billion years ago Most of the planet’s life is found from 3 meters below Most of the planet’s life is found from 3 meters below

the ground to 30 meters above it and in the top 200 the ground to 30 meters above it and in the top 200 meters of the oceans and seas.meters of the oceans and seas.

Includes portions of the hydrosphere, the lithosphere, Includes portions of the hydrosphere, the lithosphere, and the atmosphere.and the atmosphere.

What is the Hydrosphere?What is the Hydrosphere? It is all the water in the world.It is all the water in the world. Physical formsPhysical forms

SolidSolid LiquidLiquid GasGas

Includes the oceans, rivers, Includes the oceans, rivers, lakes, and even the moisture lakes, and even the moisture in the air. 97% of the earth’s in the air. 97% of the earth’s water is in the oceans. The water is in the oceans. The remaining 3% is fresh water; remaining 3% is fresh water; ¾ of the fresh water is solid ¾ of the fresh water is solid and exists in ice sheets.and exists in ice sheets.

What is the Lithosphere?What is the Lithosphere? It is the outer layer of the Earth’s It is the outer layer of the Earth’s

crust composed of soil and rocks.crust composed of soil and rocks. This crust is inorganic and is This crust is inorganic and is

composed of mineral.composed of mineral. Can change with movement of Can change with movement of

platesplates EarthquakesEarthquakes Mountain-buildingMountain-building VolcanoesVolcanoes Continental DriftContinental Drift

What is the Atmosphere?What is the Atmosphere?

It is the layer of air surrounding the Earth.It is the layer of air surrounding the Earth. Primarily nitrogenPrimarily nitrogen (79%) and (79%) and

oxygen (21%)oxygen (21%) A small amount is composed of carbon A small amount is composed of carbon

dioxide. dioxide. Provides gases for respiration and Provides gases for respiration and other gases other gases Protects organisms from UV raysProtects organisms from UV rays Absorbs energy from the sun and acts as Absorbs energy from the sun and acts as

an insulatoran insulator

Ultraviolet light

Ultraviolet light

Earth