Science.

1. Lesson 2.4
Earth’s
Atmosphere

2. Objectives
describe the
characteristics of Earth’s
atmosphere; and
At the end
of the
lesson, you
should be
able to:
1
identify the importance of
the hydrologic cycle.
2

3. Learn about it!
Atmospheric Composition
● The bulk of the atmospheric composition of Earth is
nitrogen and oxygen in which together comprises 99%.
● Only 0.9% is argon and the remaining 0.1% is trace gases.
● Carbon dioxide and ozone, although available in minute
amounts, are very essential to life on Earth.

4. Learn about it!
Atmospheric Composition
Atmospheric composition of Earth.

5. Learn about it!
Layers of the Atmosphere
● The atmosphere
is made up of 5
major layers
○ troposphere,
○ stratosphere,
○ mesosphere,
○ thermosphere,
○ exosphere.
Layers of the atmosphere

6. Learn about it!
• Troposphere is where humans and most of the biosphere
reside, and is the lowest layer.
• Stratosphere contains the ozone layer.
• Mesosphere is where meteorites burn up.
• Thermosphere is a layer with extremely high temperatures.
• Exosphere is the outermost layer of the atmosphere, and
the layer in contact with outer space.
Layers of the Atmosphere

7. Learn about it!
The Stratospheric and Tropospheric Ozone
Good and bad ozone.
• Stratospheric ozone is
good while tropospheric
ozone is bad.
• These harmful ozones
when inhaled, can irritate
the lungs and breakdown
lung tissues. Plants are
also affected by this
tropospheric ozone.

8. Learn about it!
Atmosphere’s Role in the Hydrologic Cycle
Steps in the hydrologic cycle
• The atmosphere is a crucial
part of the water cycle. It
serves as the reservoir of
large amounts of water.
• Therefore, the atmosphere
is an efficient medium to
move water around the
globe.

9. Key Points
The 5 layers of the atmosphere are: troposphere,
stratosphere, mesosphere, thermosphere, exosphere
Nitrogen and oxygen make up bulk of the gases in the
atmosphere
The atmosphere is crucial in enabling and maintaining
life on Earth.
1
2
3

10. Check Your Understanding
1. It is the coldest layer of the atmosphere.
2. It is the layer where bad ozone is found
3. It is a layer that protects us from the sun’s harmful UV
radiation.
4. It protects Earth from the impact of space debris.
5. It is the atmospheric layer where humans live.
Identify the layer of the atmosphere being
described in each item.

11. Challenge Yourself
What will happen if there will be no more hydrological cycle?

12. Bibliography
Naotatsu Shikazono. 2012. Introduction to Earth and Planetary System Science: New View of Earth,
Planets and Humans,Germany:Springer Science & Business Media.
Renu Anand. 2016.The Story of Planet Earth,New Delhi: The Energy and Resources Institute (TERI).
Ronald Martin. 2012. Earth's Evolving Systems: The History of Planet Earth, Massachusetts: Jones &
Bartlett Publishers.
Michael Pidwirny. 2016. Chapter 4: Solar Radiation and Earth: Single chapter from the eBook
Understanding Physical Geography, Our Planet Earth Publishing.
Rubin, Kenneth. 2016. Geochemistry Lecture 33 Accessed March 17, 2017.
https://www.soest.hawaii.edu/krubin/GG325/lect33.pdf.