GBlab5GHGs

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School

University of Colorado, Boulder *

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Course

1070

Subject

Geography

Date

Dec 6, 2023

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docx

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6

Uploaded by BrigadierGorilla17107

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Lab 5 Report Name: ___Grant Bowditch_________________ Partners: _Chase, Carter, _______________ Please paste your Excel data and graph below this line. Highlight everything you need in Excel, copy, and then use ‘Paste Special’ to paste as an image (e.g., PNG, PDF, etc.). You can take a screenshot as well and paste it here, but please make sure it is easily viewable by your TA.
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 heat or IR radiation. The plastic sheets act like a blanket like the atmosphere and traps the radiation and heat, otherwise known as the greenhouse effect. 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 absorb or trap and 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 down.
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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. 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 and reflecting IR radiation and heating the atmosphere. Whereas the sheets might represent all Greenhouse gases OTHER than water vapor that are not as good at absorbing. 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?
This is because the water absorbs a lot of the heat or IR radiation and thus has a similar temperature to the IR 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 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 and reflecting IR radiation, and thus is best at keeping the atmosphere warm. So, in dry areas, there is less IR radiation absorbed and reflected down, which results in a cooler atmosphere and 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. One potential source of error for experiment 2 could be heat loss to the surroundings of the hot pot, which would result in lower temperatures than expected and skewed results. To reduce this error, you could potentially insulate the hot pot or isolate it in an area where it doesn’t lose as much heat.
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 readings. 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 skew the results. Also, while placing each successive plastic sheet over the thermometer while holding it, it could’ve moved and read a different spot in the sky. A way to reduce this would be to have some sort of tripod to put the thermometer on to get consistent readings, and an accurate spot in the sky. 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 - a massive difference in reflective capability. This melting of the ice will cause higher sea levels as well as further melting of polar and glacial ice.
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