# Glass Layers

Part 1: Glass Layers (Greenhouse)

Click on the “Glass Layers” tab at the top of the screen of the Greenhouse Effect Simulation.

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.

Hypothesis: Write what happens to make the inside of a car feels so much warmer than its surroundings on sunny days.

I think that, since there is not much air circulation inside of a car when it is not turned on, the sunlight becomes trapped, therefore making the inside of the car very warm.

2a. What do the yellow dots moving down represent?

Sunlight photons

2b. What do the red dots represent?

Infrared light

2c. Record the approximate temperature “inside the greenhouse” before adding glass panes:

2 Fahrenheit

Prediction: Make a prediction about what will happen when you add a glass pane:

I think that the sunlight photons (yellow dots) will be able to pass through

2d. What do the sunlight photons do when they hit the glass from the top? Do they all do the same thing?

The sunlight photons pass through. They all do the same thing.

2e. What do the infrared photons do when they hit the glass from the bottom? Do they all do the same thing? Be specific.

The infrared photons either pass through or shoot back toward earth.

2f. What is the new temperature “inside the greenhouse?”

80 Fahrenheit

2g. Based on the observations of the photons, why does the temperature change?

The temperature changes because more sunlight photons are passing through.

Now add one more glass pane and watch. Then add the third glass pane.

2h. What happens to the temperature as additional glass panes are added?

The temperature inside increases.

2i. Explain why this happens by observing the photons.

The added pane is able to trap in the photons that passed through the first glass pane.

2k. Before proceeding to the earth, predict how what you have discovered regarding greenhouses might apply to the earth and its atmosphere.

The greenhouse gases that surround us in the atmosphere act very similarly to the glass panes shown in the simulation, because they are both able to capture and trap heat.

Part 2: The Earth’s Atmosphere

Click on the “Greenhouse Effect” tab at the top.

3a. What do the yellow dots moving down represent?

Sunlight photons

3b. What do the red dots represent?

Infrared photons

3c. Watch the red dots carefully. Do they all move upwards? Why or why not?

No, some of them move back down because they are being trapped by the greenhouse gases.

3d. Is the behavior of the photons more similar to the greenhouse simulation with or without glass panes?

It is more similar to the simulation with glass panes.

3e. Which time period do the default conditions represent?

They represent the conditions of todays.

With the Atmosphere set to “Today,” fill out the table below:

Record the composition of the atmosphere (on the right side of the screen):

 Gas Amount H2O 73% rel. humidity CO2 388 ppm CH4 1.843 ppm N2O .317 ppm

(ppm means “parts per million”)

Record the temperature on the thermometer:

 K (kelvin) 288 °F (degrees Fahrenheit) 59 °C (degrees Celsius) 13

Note: this indicates the average global temperature

Make a prediction about what will happen if you reduce the amounts of greenhouse gases:

I think the temperature will drop if there are less greenhouse gases.

Test your prediction: reduce the greenhouse gas concentration to “None”.

3f. Is the behavior of the photons more similar to the greenhouse simulation with or without glass panes?

It is more similar to the greenhouse simulation that has no glass panes.

3g. What is the average global temperature?

-1 Fahrenheit

3h. Considering the behavior of the photons, why does the temperature drop so much?

Because none of the infrared photons are being absorbed.

Test your prediction: increase the greenhouse gas concentration to “Lots.”

3i. Is the behavior of the photons more similar to the greenhouse simulation with or without glass panes?

With the glass panes

3j. What is the average global temperature?

Around 70 Fahrenheit

3k. Considering the behavior of the photons, why does the temperature increase?

The infrared photons are being absorbed, thus trapping heat.

Click on “1750” on the right side of the screen to set the atmosphere to the proportions for that date. Wait a few minutes for the temperature to stabilize. Fill out the table below.

Record the composition of the atmosphere (on the right side of the screen):

 Gas Amount H2O 70% rel. humidity CO2 280 ppm CH4 .730 ppm N2O .270 ppm

(ppm means “parts per million”)

Record the temperature on the thermometer:

 K (kelvin) 286 °F (degrees Fahrenheit) 56 °C (degrees Celsius) 13

Note: this indicates the average global temperature

3l. Which gas(es) changed from the “Today” value? Did each one go up or down?

The degrees Fahrenheit and Kelvin, they went down.

3m. What is the average global temperature? Is this hotter or cooler than the “Today” value? How does this agree/disagree with your experiments changing the greenhouse gas amounts from “none” to “a lot” in the previous part?

The average is 56 degrees Fahrenheit, which is cooler than it is today. Since there were less greenhouse gases, it correlates with what happened when there were no greenhouse gases in the atmosphere (the drop in temperature).

Click on “Ice Age” on the right side of the screen to set the atmosphere to the proportions for that date. Wait a few minutes for the temperature to stabilize. Fill out the table below.

Record the composition of the atmosphere (on the right side of the screen):

 Gas Amount H2O ? CO2 180 ppm CH4 .380 ppm N2O .215 ppm

(ppm means “parts per million”)

Record the temperature on the thermometer:

 K (kelvin) 272 °F (degrees Fahrenheit) 32 °C (degrees Celsius) 0

Note: this indicates the average global temperature

3n. Which gas(es) changed from the “1750” value? Did each one go up or down?

All of them changed, and all of them went down.

3o. What is the average global temperature? Is this hotter or cooler than the “Today” value? How does this agree/disagree with your experiments changing the greenhouse gas amounts from “none” to “a lot” in the previous part?

The average global temperature is 32 Fahrenheit. This is lower than the today value, and it also coincides with what happens when there are less greenhouse gases.

Part 3: Conclusions

From your observations and data above, what correlations did you find?

How does the greenhouse effect affect temperature on Earth? Is the greenhouse effect “good” or “bad” for Earth, or both? Why? Is there another planet in the solar system that has an extreme “global warming” phenomena due to the greenhouse gasses?

I found that without greenhouse gases, the earth would be much cooler, and with greenhouse gases, the earth would be much, much hotter. The greenhouse effect is good for earth in moderation, because the earth would be much too cold with greenhouse gases and much too warm to sustain life without them. The same greenhouse effect happens in Venus, but to a much more extreme degree. The atmosphere in Venus is made up mostly of carbon dioxide, which is a greenhouse gas. Here on earth, carbon dioxide makes up a very tiny fraction of our atmosphere, which explains why Venus has such extreme global warming.

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