Importance of the Atmosphere
Dana Desonie, Ph.D.
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Printed: August 4, 2016
AUTHOR
Dana Desonie, Ph.D.
www.ck12.org
C HAPTER
Chapter 1. Importance of the Atmosphere
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Importance of the
Atmosphere
• Define the atmosphere.
• Describe the roles the atmosphere plays on Earth.
Why is the atmosphere important?
Why is Earth the only planet in the solar system known to have life? The main reason is Earth’s atmosphere.
Organisms need the gases in the atmosphere to live. Water is also essential for life. Water vapor is one of the gases
in the atmosphere. Green algae, like in this photo, are primitive life.
The Atmosphere
The atmosphere is a mixture of gases that surrounds the planet. We also call it air. The gases in the atmosphere
include nitrogen, oxygen, and carbon dioxide. Along with water vapor, the atmosphere allows life to survive.
Without it, Earth would be a harsh, barren world.
The Atmosphere’s Importance
We are lucky to have an atmosphere on Earth. The atmosphere supports life and is also needed for the water cycle
and weather. The gases of the atmosphere even allow us to hear.
The Atmosphere and Living Things
Most of the atmosphere is nitrogen, but it doesn’t do much. Carbon dioxide and oxygen are the gases in the
atmosphere that are needed for life.
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• Plants need carbon dioxide for photosynthesis. They use sunlight to change carbon dioxide and water into
food. The process releases oxygen. Without photosynthesis, there would be very little oxygen in the air.
• Other living things depend on plants for food. These organisms need the oxygen plants release to get energy
out of the food. Even plants need oxygen for this purpose.
The Atmosphere and the Sun’s Rays
The atmosphere protects living things from the Sun’s most harmful rays. Gases reflect or absorb the strongest rays
of sunlight (Figure 1.1).
FIGURE 1.1
The atmosphere shields Earth from the most harmful solar rays.
The Atmosphere and Earth’s Temperature
Gases in the atmosphere surround Earth like a blanket. They keep the temperature in a range that can support life.
The gases keep out some of the Sun’s scorching heat during the day. At night, they hold the heat close to the surface,
so it doesn’t radiate out into space.
The Atmosphere and Earth’s Water
The image below shows the role of the atmosphere in the water cycle (Figure 1.2). Water vapor rises from Earth’s
surface into the atmosphere. As it rises, it cools. The water vapor may then condense into water droplets and form
clouds. If enough water droplets collect in clouds, they may come together to form droplets. The droplets will fall
as rain. This how freshwater gets from the atmosphere back to Earth’s surface.
The Atmosphere and Weather
Without the atmosphere, there would be no clouds or rain. In fact, there would be no weather at all. Most weather
occurs because the atmosphere heats up more in some places than others.
The Atmosphere and Weathering
Weather makes life interesting. Weather also causes weathering. Weathering is the slow wearing down of rocks on
Earth’s surface. Wind-blown sand scours rocks like sandpaper. Glaciers of ice scrape across rock surfaces like a file.
Even gentle rain may seep into rocks and slowly dissolve them. If the water freezes, it expands. This eventually
causes the rocks to crack. Without the atmosphere, none of this weathering would happen. Rocks at the surface
would be pristine and unaltered.
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Chapter 1. Importance of the Atmosphere
FIGURE 1.2
The atmosphere is a big part of the water
cycle. What do you think would happen to
Earth’s water without it?
The Atmosphere and Sound
Sound is a form of energy that travels in waves. Sound waves cannot travel through empty space, but they can travel
through gases. Gases in the air allow us to hear most of the sounds in our world. Because of air, you can hear birds
singing, horns tooting, and friends laughing. Without the atmosphere, the world would be a silent, eerie place.
Summary
• The atmosphere is made of gases that are essential for photosynthesis and other life activities.
• The atmosphere is a crucial part of the water cycle. It is an important reservoir for water, and the source of
precipitation.
• The atmosphere moderates Earth’s temperature. Weather takes place in the atmosphere.
• Without air, Earth would be silent.
Review
1. What gases are used and expelled by photosynthesis and respiration?
2. How does the atmosphere keep Earth’s temperature moderate?
3. How does the atmosphere play an important role in the water cycle?
Explore More
Use the resource below to answer the questions that follow.
MEDIA
Click image to the left or use the URL below.
URL: https://www.ck12.org/flx/render/embeddedobject/58915
1. What is the atmosphere?
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2.
3.
4.
5.
6.
Where does weather occur?
What does the atmosphere protect us from? Which layer?
What would happen if we didn’t have the protective layer in the previous question?
What happens in the mesosphere?
What is made in the thermosphere?
References
1. Laura Guerin. The atmosphere shields Earth from the most harmful solar rays . CC BY-NC 3.0
2. Laura Guerin. The atmosphere is a big part of the water cycle . CC BY-NC 3.0
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