Download The Biosphere

The Four Spheres
of the Earth
“Extraordinarily complex, extremely
diverse, infinitely renewing, and yet
ultimately fragile” Tom. L. McKnight
What is Physical Geography?
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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
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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
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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?
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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?
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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?
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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
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Earthquakes
Mountain-building
Volcanoes
Continental Drift
What is the Atmosphere?
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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