Greenhouse Effect
Name: _______________________
Objective: To describe how the “greenhouse effect” affects temperature on the earth and to use evidence to
support whether the “greenhouse effect” is good or bad for the earth.
Introduction: Global warming is perhaps the “hottest” topic in today’s headlines. The cause of warming is
usually blamed on the “greenhouse effect” or “greenhouse gases.” The following simulation will allow you to
first examine how the “greenhouse effect” works in a greenhouse. You will then experiment with a simulation
of the earth’s atmosphere where the concentration of greenhouse gases can be varied. Finally, you will use the
results of the two simulations to describe how the “greenhouse effect” affects temperature on the earth and
discuss whether the “greenhouse effect” is good or bad for the earth.
Before diving into the whole issue of global warming, try to picture sitting in an enclosed car on a cold but
sunny day … pretty comfortable, isn’t it. Now imagine sitting in that same car on a hot, sunny day. Don’t hold
that image too long. You’ll fry just thinking about it.
Go to http://phet.colorado.edu/en/simulation/greenhouse
Part I: Greenhouse Simulation

Select the “Glass Layers” tab.
1. What do the yellow stars represent and where do they originate from? What about red stars?
2. Record the approximate temperature “inside the greenhouse” before adding glass panes. ___________

Add one glass pane.
3. What do the sunlight photons do when they hit the glass from the top?
4. **What do the infrared photons do when they hit the glass from the bottom? Be specific.
5. What is the new temperature “inside the greenhouse?” ___________________
6. **Based on the observations of the photons, why does the temperature go up so much?
7. What happens to the temperature as additional glass panes are added?
8. **Explain why this happens by observing the photons.
Part II: Earth Simulation

Select the “Greenhouse Effect” tab.
9. Which greenhouse gases are considered by the simulation?

The thermometer represents the average global temperature.
10. What is the average global temperature for the “today” simulation?
11. Is the behavior of the photons more similar to the greenhouse simulation with or without glass panes?
Why?

Reduce the greenhouse gas concentration to “None”.
12. Is the behavior of the photons more similar to the greenhouse simulation with or without glass panes?
13. What is the average global temperature?
14. **Considering the behavior of the photons, why does the temperature drop so much?

Increase the greenhouse gas concentration to “Lots.”
15. What is the average global temperature?
16. Considering the behavior of the photons, why does the temperature increase?
17. Experiment with other periods in earth’s history or add clouds and record interesting observations.
Part III: Photon Absorption
 Turn on the photon gun and play around with the controls to get familiar with the simulation. Once ready,
follow the following instructions:
-
-
Turn on the ray gun so it fires one photon every 4 seconds or so.
Once it is firing at that pace, click the button to make CH4 (methane) the molecule in the path of the
photon.
Start counting the photons and recording the behavior of them when they reach methane. The two
choices for behavior are either:
o Absorbed and deflected
o Passed through
Stop recording once 10 photons have been fired at the molecule
-
Repeat the above steps for CO2, H2O, and N2
Gas
Individual Data
Class Data
Number Number passing Number
Number passing
absorbed through
absorbed
through
CH4
CO2
H2O
N2
18. Categorize the above gases as either “Greenhouse Gases” or “Not Greenhouse Gases”.
19. According to this activity, what differentiates a greenhouse gas from one that is not? Be specific as to
what is occurring with the molecule’s shape.
20. Can you come to any conclusion on strength of greenhouse gases based upon class data? Why or why
not?

Here is information about composition of the atmosphere for three planets in our solar system. Use this
information to answer the following questions.
21. If water is found in greater concentration in the Earth’s atmosphere, why do you think CO2 gets most of
the publicity?
22. Here is a challenge: How might CO2 increasing in concentration create a positive feedback loop with
water vapor concentration?
Part IV: Conclusion
 Go to this link: http://earthguide.ucsd.edu/virtualmuseum/climatechange2/11_3.shtml and answer the
following questions:
23. List all the sources and all the sinks for methane as referenced in the article.
24. Summarize the section on methane hydrates.
25. Your parents come up to you and ask if the greenhouse effect is “good or bad” for humans. Answer this
question drawing on information from this assignment. (5 point formative assignment)