Environmental Science
Name: ______________________________
Title
Goal: The student will describe the composition of the Earth’s atmosphere and describe the layers of the
Earth’s atmosphere.
Vocabulary:
1. Atmosphere
2. Troposphere
3. Stratosphere
4. Ozone
Notes: Chapter 7.1: The Atmosphere
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Earth is surrounded by a ____________________ of gases known as the atmosphere
_____________________, oxygen, carbon dioxide and other gases are all parts of this mixture
The atmosphere changes constantly as these gases are _________________ and ________________________
(ex: _______________________ take in O2, give off CO2; plants take in CO2 and give off O2; volcanic eruptions
___________ gases; cars add and remove gases)
Our atmosphere (this layer of gases) is what makes _______________ possible on the Earth by insulating Earth’s
surface, slowing the rate at which ________________from the sun is lost, thus allowing us to survive
Extends from the ___________________ of Earth to hundreds of kilometers ___________________ the surface
How Photosynthesis Changed the Atmosphere
• Earth’s __________________ atmosphere probably contained very little ______________________; early
organisms (bacteria) __________________________ the ability to perform photosynthesis
• During photosynthesis, some ________________________ from water and carbon dioxide formed oxygen gas,
which entered the _____________
• As plants multiplied, oxygen in the air ______________________________
• _____________________________, during cellular respiration, release carbon dioxide into the atmosphere,
creating the balance between the two; thus, sustaining the balance for life on _________________and keeping the
_________________within a temperature range for life to exist
Composition of the Atmosphere
• AIR = 78% ________________________ (entering when volcanoes erupt, dead plants and animals decay) and
21% ___________________________ (primarily produced by plants); remaining 1% is made up of water vapor,
argon, carbon dioxide, methane and other gases
• Most important gases for ____________________________ is oxygen (cellular respiration); carbon dioxide for
________________ (photosynthesis)
• Atmosphere protects Earth’s organisms by: ___________________________ from sun’s ultraviolet radiation,
allows light to reach the ________________________ and keeps the Earth’s temperatures stable
Air Pressure
 Earth’s atmosphere is pulled toward Earth’s surface by _____________________ making the atmosphere denser
near the surface
 Almost the entire mass of Earth’s atmospheric gases are located with ________________ of the surface; fewer
_______________ molecules are found at altitudes above 30 km (less pressure to push downward)
 Air becomes less dense as elevation ____________________; breathing becomes more difficult the higher you go
The Layers of the Atmosphere
• Atmosphere is divided into 4 individual ________________ (less dense the farther away from Earth) based on
________________________________ changes that occur at different distances above the Earth’s surface
• Troposhere – _____________________ to the earth; extends from surface outward about 18 km; contains 90% of
atmosphere’s gases; layer where weather occurs; most _____________________atmospheric layer; temperature
decreases as altitude increases
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Stratosphere – extends from 18 km to about 50 km (about 30 miles); temperature _________________ as altitude
increases as a result of _____________________ in the stratosphere absorbing the sun’s ultraviolet energy and
warming the air
Ozone (O3) is a molecule made up of _____________________ oxygen; almost all O3 is concentrated in ozone
layer in the stratosphere; Because ozone ____________________ UV radiation, it reduces the amount of UV
___________________________ that reaches the Earth. UV rays cause damage to __________________cells
Mesosphere – extends from 50 to 80 km; _____________________ layer of the atmosphere, measured as low as 93 degrees C.
Thermosphere – extends from 80 to 550 km; located _______________________from Earth’s surface; nitrogen
and oxygen absorb _____________________ radiation which results in temperatures above 2000 degrees C.
(wouldn’t feel hot because air particles are so far apart they never ________________, so little heat is transferred)
Nitrogen and oxygen (lower region of thermosphere) ___________________ harmful radiation (x-rays, gamma
rays) causing them to become electrically charged (called ions). The lower region of the atmosphere is sometimes
called the ionosphere. These _______________ radiate energy as light and oftentimes ___________________ in
spectacular colors in the night sky (North and South poles)
Lesson Reflection:
Draw the layers of the atmosphere. Color and label the diagram.
Assessment:
1. Describe the composition of Earth’s atmosphere
2. Describe a characteristic of each layer of the atmosphere.
Lesson Extension (Technology/Application/Connection to Real World):
Watch YouTube Video on Felix Baumgartner’s free fall from space!