Greenhouse Effect: Part I

Greenhouse Effect: Part I

Website: http://phet.colorado.edu/en/simulation/greenhouse. Click on “Run Now” to run the simulation.

What do the yellow dots moving down represent?____________________________________

What do the red dots represent?__________________________________ Watch them carefully. Do they all move upwards? __________________________________ Why or why not? (Slow down the animation to see this more clearly.)

Today

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

H

O (water vapor) CO

(carbon dioxide) CH

(methane) N

O (nitrous oxide)

(ppm means “parts per million”)

Record the temperature on the thermometer:

K (kelvin)

°F (degrees Fahrenheit)

°C (degrees Celsius)

1750

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.

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

H

O (water vapor) CO

(carbon dioxide) CH

(methane) N

O (nitrous oxide)

Record the temperature on the thermometer:

K (kelvin)

°F (degrees Fahrenheit)

°C (degrees Celsius)

Ice Age

Click on “Ice Age” on the right side of the screen to set the atmosphere to the proportions for Earth’s last major ice age. Wait a few minutes for the temperature to stabilize.

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

H

O (water vapor) CO

(carbon dioxide) CH

(methane) N O (nitrous oxide)

Record the temperature on the thermometer:

K (kelvin)

°F (degrees Fahrenheit)

°C (degrees Celsius)

Glass Layers

Click on the “Glass Layers” tab at the top of the screen. On the right side of the screen, set the Number of Glass Panes to “1”.

Watch the yellow photons carefully. Do they pass through the glass or are they blocked? ___________________

Watch the red photons carefully. Do they pass through the glass or are they blocked? _____________________

(Move the slider at the bottom of the screen to slow down the animation if necessary.) Record the temperature on the thermometer: __________K, ___________ °F.

Your family’s car has been parked outside on a cold but sunny day. When you get in the car, it is much warmer than the air outside. Explain how this can happen.

Photon Absorption

Click on the “Photon Absorption” tab at the top of the screen.

A methane molecule sits in the middle of the screen. Use the slider on the left side of the screen to shoot some infrared photons at the molecule. Do all the photons pass through the molecule? ____________________

When a photon gets absorbed, what happens next? ______________________________ _______________

When a new photon is emitted, is it always sent in the same direction? _________________________________

Use the buttons on the right side of the screen to test different molecules. Record your observations in the table below. Write “yes” if any photons get absorbed; write “no” if no photons get absorbed.

Which gases absorb photons?

Infrared Photons Visible Photons CH

(methane)

CO

(carbon dioxide) H

O (water vapor) N

(nitrogen) O

(oxygen)

Which three gases contribute to the greenhouse effect in our atmosphere?

Which two gases do NOT contribute to the greenhouse effect?

Greenhouse Effect: Part II

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.

Directions: Steps in bold font require a written response. A double asterisk is placed in front of questions requiring a complete response.

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.

1) **Hypothesize why the inside of a car feels so much warmer than its surroundings on sunny days.

2) Go to http://phet.colorado.edu/en/simulation/greenhouse 3) Click the ‘Reset All’ Button to start the simulation again.

Part I: A Greenhouse Simulation

Both the yellow and red stars represent forms of energy in the form of photons: the yellow are visible light, the red are heat.

4) Record the approximate temperature “inside the greenhouse” before adding glass panes.

5) Add one glass pane.

6) **What do the sunlight photons do when they hit the glass from the top?

7) **What do the infrared photons do when they hit the glass from the bottom? Be specific.

10) What happens to the temperature as additional glass panes are added?

11) **Explain why this happens by observing the photons.

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

Part II: The Earth Simulation

13) Select the “Greenhouse Effect” tab.

14) Which greenhouse gases are considered by the simulation?

15) Which time period do the default conditions represent?

The thermometer represents the average global temperature.

16) What is the average global temperature for the “today” simulation?

17) Is the behavior of the photons more similar to the greenhouse simulation with or without glass panes?

18) Reduce the greenhouse gas concentration to “None”.

19) Is the behavior of the photons more similar to the greenhouse simulation with or without glass

20) What is the average global temperature?

21) **Considering the behavior of the photons, why does the temperature drop so much?

22) Increase the greenhouse gas concentration to “Lots.”

23) What is the average global temperature?

24) **Considering the behavior of the photons, why does the temperature increase?

25) Experiment with other periods in earth’s history or add clouds and record interesting observations.

Part III: Completely answer the following questions. YOU MUST USE EVIDENCE FROM YOUR OBSERVATIONS OF THE SIMULATION TO SUPPORT YOUR ANSWERS.

1. How does the “greenhouse effect” affect temperature on the earth?

2. How is the “greenhouse effect” similar to blankets on a bed?