Scattering of Light by the Atmosphere

1. Lesson 22.3
Scattering of Light by the
Atmosphere

2. Objective discuss how light is
scattered as it passes
through Earth’s
atmosphere.
1
At the end
of the
lesson, you
should be
able to:

3. Learn about It!
• Light passes through the gases
in the atmosphere and ended
up being scattered.
• The color of the sky that you
can see is the scattered light
being sent toward you.
Scattering of Light by the Atmosphere
Earth’s atmosphere

4. Learn about It!
• The atmosphere is made of several gases, mostly nitrogen
and oxygen, which are capable of scattering the light
coming from the sun.
• Those with short wavelength are scattered the most,
whereas those with long wavelength are scattered the
least.
Scattering of Light by the Atmosphere

5. Learn about It!
• It is similar to the light passing through a prism wherein the
red light deflects the smallest while the violet light deflects
the most.
• However, instead of being merely deflected, the colors with
shorter wavelength tend to scatter in all direction, while the
colors with longer wavelength stay close to the original
direction of the white light.
Scattering of Light by the Atmosphere

6. Learn about It!
• Blue sky occurs because when
the sun is at or near the zenith,
the blue light passing through
the atmosphere is scattered in
all directions.
Blue Sky
Blue sky

7. Learn about It!
• The red light diverts only a little
from the original direction of the
white light.
• Zenith is the point in the sky
directly above the observer’s
location.
Blue Sky
Blue sky

8. Learn about It!
Blue Sky
You can see blue sky
during the day
because most of the
atmosphere scatters
blue color the most.

9. Learn about It!
• White light coming the sun is
scattered less because it
passes through the least
amount of gas in the
atmosphere. Thus, you still
perceive the light from the
sun as white.
Blue Sky
Blue sky

10. Learn about It!
• Even if the shortest wavelengths are scattered the most, the
sky still appears blue instead of violet.
• This occurs because some of the violet light rays are
absorbed by the upper atmosphere.
• Another reason is that human eyes are more sensitive to
blue light than to violet light.
Blue Sky

11. Learn about It!
• During sunrise or sunset, the
sky appears as shades of red,
orange, and yellow.
• Colors with longer
wavelengths are scattered the
least, and thus, they are the
ones reaching your eyes.
Sunset and Sunrise
Sunset

12. Learn about It!
Sunset and Sunrise
During sunrise or
sunset, light from the
sun passes through
the thickest gas in
the atmosphere,
causing the
wavelengths
scattered the least to
reach the eyes.

13. Learn about It!
White Clouds
Clouds
• Clouds appear white because
the water droplets in the
clouds scatter all the color
frequencies of white light
equally.
• Before and during the rainfall,
the clouds contain a large
amount of water droplets.

14. Learn about It!
• The clouds are too thick for the
light to pass through, and as a
result, the light ends up being
absorbed.
White Clouds
Clouds

15. Key Points
The color of the sky that you can see is the scattered light
being sent toward you.
Short wavelength are scattered the most, whereas those
with long wavelength are scattered the least.
1
2
Zenith is the point in the sky directly above the observer’s
location.
3

16. Key Points
Clouds are mass of water droplets floating in the
atmosphere that scatters light differently from that of the
surrounding atmosphere.
4

17. Check Your Understanding
Identify what is described in the statement.
1. This is the point in the sky directly above the observer’s
location. Hence, you see most of the sky as blue.
2. Colors red, yellow, and orange, have this wavelengths.
3. Colors blue and violet have this wavelengths.
4. These are mass of water droplets floating in the
atmosphere.
5. Along with oxygen, this is another abundant gas in the
atmosphere.

18. Challenge Yourself
1. What causes the varying colors of the sky?
Explain your answer.
1. How is light scattered in the atmosphere?

19. Bibliography
Birky, Jennifer. “The Physics of Rainbows.” Hesston College Physics Homepage. Accessed July 3, 2016.
http://www2.hesston.edu/Physics/Rainbows/research2_paper.htm.
Castro, Joseph. “Why Are Rain Clouds Dark?” Live Science. Accessed July 3, 2016.
http://www.livescience.com/39069-why-are-rain-clouds-dark.html.
Gibbs, Philip. “Why Is the Sky Blue?” The Original Usenet Physics FAQ. Accessed July 3, 2016.
http://math.ucr.edu/home/baez/physics/index.html.
Henderson, Tom. “Mirages.” The Physics Classroom. Accessed July 3, 2016.
http://www.physicsclassroom.com/class/refrn/Lesson-4/Mirages.
Thorsen, Steffen. “Atmospheric Phenomena: Halos, Sundogs and Light Pillars.” Time and Date AS. Accessed
July 3, 2016. http://www.timeanddate.com/astronomy/optical-phenomenon.html.