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ASTRO 101 Lab4_The Greenhouse Effect

Learning Goals: Students will be able to

• Compare and contrast “light photons” and “infrared photons”.

• Identify what happens to light photons when they get to Earth and why the temperature of the earth and its atmosphere changes.

• Design experiments to observe how clouds change the photons behavior

• Design experiments to observe how greenhouse gases change the photons behavior • Compare and contrast cloud behavior and greenhouse gas behavior.

• Use the Photon Absorption tab to identify if molecules are Greenhouse Gases and give the microscopic evidence that supports your ideas.

• Explain why inside a building or car sometimes is a different temperature than outside.


• Discover when the “Ice Age” was and what was has changed about the composition of the greenhouse gases.

Important simulation information:

➢ When you start The Greenhouse Effect or use ,the earth temperature is reset to cold and light photons start coming from the sun.

➢ You might want to use the speed , pause , and step tools to help you watch the photon and temperature changes.

➢ Investigate the three tabs at the top of the simulation. Play around with these and various settings inside each tab to get a feel for how the simulation works before continuing on to the Directions below.


In a separate Word document, answer questions 1 through 6 and the Extension (on second page). Make sure to fully answer each question and all of its parts for full credit.

1. Define “light photons” and “infrared photons”

a. How are they represented in the simulation?

b. If you were talking to a friend about what you observe, how would you explain what is happening with the energy from the sun and the energy from the Earth?


“Light photons” are presented as white particles moving from the Sun to the Earth.

While “infrared photons” are presented as red particles moving from the Earth to the atmosphere.


Explanation: the energy emitted from the sun goes into the Earth and heats up the surface of the Earth, and the energy reflected from the Earth would escape from the Earth. However, some of the energy will be reflected back by the clouds in the atmosphere, finally maintaining the temperature relatively stable.

2. In the winter, weather reporters often day “It will be a very cold night because there are no clouds.”

a. Use the sim to see if you can understand why this could be true.

b. Describe your observations.

c. Would there be a difference between daytime and nighttime cloud effects? If so, what are they?

2a: If there are no clouds, more “infrared photons” would escape from the Earth and never come back to the Earth, resulting that the temperature decreases. Then it turn out to be a cold night.

2b: However, as I change the number of the clouds, it seems that little change occurs to the temperature 2c: Yes. At daytime, clouds will absorb the light photons, directly reducing the number of light photons to the Earth, finally decreasing the temperature of the Earth surface. However, at nighttime, clouds would block the escaping of the “infrared photons” from the Earth to warm up the Earth.

3. How can you make the greenhouse gases act similar to clouds?

a. Explain what you did.

b. Give the evidence to prove you made them act alike in a few different situations.

3a: I changed the number of the greenhouse gas to see how the temperature change.

3b: As I increase the concentration of the greenhouse gas, the temperature increases because much more infrared photons are blocked back to the Earth to warm up the surface. Instead, when I decrease the concentration of the greenhouse gas, the temperature decreases obviously.

4. What do you notice about greenhouse gas effect on photons that is different from clouds? Give examples from situations that you made in the sim to support your ideas.

I notice that the greenhouse gas effect on photons becomes more evident than the cloud.

For example, when I changed the greenhouse gas concentration into “Lots” direction, the infrared phonons were reflected and the temperature increased a lot. While when I changed the number of the clouds, a small amount of infrared photons were reflected back to the Earth but no obvious change was observed in temperature.

5. Use the Photon Absorption tab to identify which of the molecules provided in the sims are Greenhouse Gases. State microscopic evidence that supports your ideas.

The greenhouse gases are mainly determined by the reflection and absorption of the infrared photons, I set the infrared photon to pass through every kind of the pure gases: CH4, CO2, H20, N2, O2. And I

observe that N2 and 02 can barely reflect the infrared photons. H20 and CH4 can partly reflect the photons. Only C02 could reflect relatively much infrared photons, which suggests that it is the greenhouse gas.

6. Why do you think the inside of a car feels so much warmer than its surroundings on sunny days?

a. How can you use the sim to test your ideas?

b. Describe your experiment and state some evidence that explain the different temperatures on a microscopic level using photons.

6.Because the glass layers of the car will also absorb energy from the sun and reflect the infrared photons back to the car to heat up the car.

6a: I try to test my idea through adjusting the number of the glass layers to see how the temperature change.

6b: When I adjust the number of the glass layer from 0 to 3, it is observed that the number of the reflected infrared photons increases, and the temperature increases evidently.

Extension: Discover when the “Ice Age” was and what was has changed about the composition of the greenhouse gases. Include citations for your answers. How did the sim developers usee research information in the sim design?

There are many suggestions and perceptions on the issue, including: - a worldwide climate change - the placement of the continents - the greenhouse affect - changes in the earths orbit - and changes in the Suns energy among others. I am going to concentrate on The Greenhouse Effect and how it possibly caused our last Ice Age.

Changes in the concentration of carbon dioxide in the atmosphere is a strong candidate to explain why the overall climate of Earth changes. As you are aware, carbon dioxide influences the mean global temperature through the greenhouse effect. Solar radiation entering the Earths atmosphere is predominately short wave, while the heat radiating form the earth is long wave. As we have learned in class, water vapor, methane, carbon dioxide, along with traces of other gases in our atmosphere absorb this long wave radiation. Because the atmosphere of the earth doesnt allow this long wave radiation to leave, the solar energy is then trapped and forces the temperature of the earth to increase. If not for the presence of our atmosphere, earths temperatures would be well below the freezing point for water.

Throughout a million year period, the average amount of carbon dioxide in our atmosphere is affected by four primary fluxes. Flux of carbon dioxide due to (a) metamorphic degassing, (b) weathering of organic carbon, ( c) weathering of silicates, and (d) burial of organic carbon. The degassing reactions as in volcanic activity and the combing of organic carbon with oxygen release carbon dioxide into the atmosphere. While the burial of organic carbon found in soils and mud from swamps removes the carbon dioxide from our atmosphere. This organic carbon is buried before it is able to decay.

Plate tectonics disrupt these carbon fluxes as well, and in a variety of ways. Some tending to elevate and others tending to lower the atmospheric carbon dioxide level. Some experts believe that the early warm trend 55 million years ago was caused by elevated atmospheric carbon dioxide and that a subsequent decrease in atmospheric carbon dioxide led to the cooling trend over the past 52 million years. One theory proposed as the cause of this decrease in carbon dioxide levels in our atmosphere is that mountain uplift lead to enhance weathering of silicate rocks, and thus the removal of carbon dioxide from the atmosphere.

The sim developers could adjust the concentration of each type of gas to observe how the temperature would evolve.




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