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School
University of Colorado, Boulder *
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Course
1070
Subject
Geography
Date
Dec 6, 2023
Type
docx
Pages
6
Uploaded by BrigadierGorilla17107
Lab 5 Report
Name: ___Grant Bowditch_________________
Partners: _Chase, Carter,
_______________
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[EMBED EXCEL DATA / GRAPH HERE]
Intro Question 1 (5pts):
What percent of incoming solar radiation is absorbed by the atmosphere?
22.6 %
Intro Question 2 (5pts):
The thick red arrows in the diagram represent fluxes of infrared radiation. To
get an idea of how opaque the atmosphere is to IR radiation coming off the
surface, calculate the percent of IR emitted from the surface that is absorbed
by the atmosphere.
0.899 or about 90%
Question 1 (10 points):
The pot of hot water in Experiment 2 can be considered a simulation of the
warm surface of the Earth with the plastic sheets simulating the effects of
the atmosphere. In this case, the IR thermometer measurement simulates
the amount of radiation escaping through Earth’s atmosphere.
In the outdoor Experiment 4 you measured the infrared radiation coming
back down from the sky, with the plastic sheets also simulating the effects of
the atmosphere. This time, the IR thermometer reading simulates the
amount of radiation returned to the ground by the atmosphere.
a.
When you add plastic sheets, does the amount of IR radiation escaping
into the room from the hot pot (or, by analogy, escaping from the Earth
into space) increase or decrease? What physical processes are making
this happen?
Its decreases. This is caused by absorption and each added layer absorbs
more IR radiation.
b. In the sky experiment, does the addition of plastic sheets increase or
decrease the amount of IR radiation entering the IR thermometer? What
physical processes are making this happen?
It increases the amount of IR radiation entering the thermometer. The sheets
resemble the layers of the atmosphere and clouds that reflect the IR
radiation back down towards earth (or back into the thermometer). The more
layers the higher reflection capabilities which results in a higher amount of IR
radiation.
Question 2 (10 points):
Greenhouse gases (GHGs) absorb certain wavelengths of longwave radiation.
GHGs in the atmosphere then re-emit this longwave radiation in all
directions, much of which is returned to Earth’s surface. This is called “the
Greenhouse Effect” and without it, life as we know it could not exist on Earth.
The most prevalent molecules in the atmosphere,
N
2
and O
2
, are NOT
GHGs
since they do not absorb or emit well in the infrared.
a. Does the introduction of more water vapor, carbon dioxide, and other
Greenhouse gases into the atmosphere correspond to an increase or
decrease in the number of plastic sheets?
It corresponds to an increase in plastic sheets. This is because with more
layers, not as much GHG’s can escape through, and they’re reflected back
down.
b. In theory, should an increase of Greenhouse gases in the atmosphere lead
to warmer or cooler surface temperatures? Explain your answer.
An increase in greenhouse gases should lead to a warmer surface temperature. This is because
greenhouse gases in the atmosphere absorb some of the radiation being emitted from earth,
which causes the atmosphere to get warmer. As the atmosphere gets warmer, it makes Earth’s
surface warmer as well.
Question 3 (10 points):
a. Using bullet points, clearly list and label the following:
o
the IR temp. measured through 1 sheet of plastic with a
hot water background (Experiment 2)
51.7º Celsius.
o
the IR temp. measured through the plastic cup full of water
with a hot water background (Experiment 3)
19.1º Celsius.
o
the dial temperature measured in the plastic cup full of
water (Experiment 3)
22º Celsius.
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b. Over the heated hot pot, why is the measured IR temperature through the
plastic cup full of water (Experiment 3) lower than the IR temperature
measured through one sheet of plastic (Experiment 2)?
The reason for this is because the cup full of water represents the water
vapor in the atmosphere, which is the best greenhouse gas at absorbing IR
radiation and heating the atmosphere. Whereas the sheets might represent
all Greenhouse gases OTHER than water vapor.
c. Over the heated hot pot, why is the measured IR temperature through the
plastic cup full of water similar to the dial temperature of the water in the
plastic cup itself?
Question 4 (10 points):
The composition of the atmosphere is as follows: Nitrogen 78%, Oxygen
21% , Water (as vapor and water/ice clouds) about 1% , Argon 0.9% , and
Carbon Dioxide 0.04%. When you pointed your IR thermometer to the sky,
you measured the radiation emitted by molecules of the various substances
in the atmosphere.
a.
Which one of the five substances listed above do you think is
responsible for most of the emitted IR that you measured?
Water Vapor
b. Explain why dry regions (deserts) typically have cooler nights than
moist regions, even if the regions considered are both at the same
latitude, same altitude, and far from the oceans.
The reason for this is because water vapor in the atmosphere is the best
greenhouse gas at absorbing IR radiation, and thus is best at keeping the
atmosphere warm. So in
dry areas, there is less IR radiation absorbed, which
results in a cooler atmosphere and with that also comes cooler surface
temperatures.
Conclusion Question 1 (10pts):
Identify 1 potential physical or experimental source of error for Experiment 2
(hot water experiment with sheets) and explain how one might reduce that
error.
Conclusion Question 2 (10pts):
Identify 1 potential physical or experimental source of error for Experiment 4
(sky experiment with sheets) and explain how one might reduce that error.
One source of error for the outdoor experiment could be the height in the sky
that you took the reading. If you were to point the thermometer more
towards the horizon, your readings would be coming from further away than
if you pointed it directly up in the sky, which would definitely skew the
results.
Conclusion Question 3 (5pts):
98% of climate scientists agree that greenhouse gas loading is the primary
cause of the increase in surface air temperatures in the last 50 years. As
surface energy builds and the surface warms, explain one
feedback
(Links to
an external site.)
that could potentially amplify that temperature increase.
Or, explain one feedback that could potentially counteract or abate the
warming. Keep in mind that a feedback is initiated by the surface warming
itself (so references to asteroids or other external phenomena aren't going to
win points here).
One feedback loop that could amplify a temperature increase on Earth is the
melting/removal of ice. Rising atmospheric and surface temperatures are
causing the Arctic, Greenland, and Antarctic ice sheets to melt, and once
they do, temperature increases will be exacerbated. This is because the ice
sheets reflect 84% of incoming solar radiation, whereas water reflects as low
as 5% of incoming solar radiation. This is a massive difference in reflective
capability,
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