PHET Greenhouse Effect Simulation
Website: http://phet.colorado.edu/en/simulation/greenhouse. 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?
Today
Record the composition of the atmosphere
(on the right side of the screen):
H2O (water vapor)
CO2 (carbon dioxide)
CH4 (methane)
N2O (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):
H2O (water vapor)
CO2 (carbon dioxide)
CH4 (methane)
N2O (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):
H2O (water vapor)
CO2 (carbon dioxide)
CH4 (methane)
N2O (nitrous oxide)
Record the temperature on the
thermometer:
K (kelvin)
°F (degrees
Fahrenheit)
°C (degrees Celsius)
Questions:
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?
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
CH4 (methane)
CO2 (carbon
dioxide)
H2O (water vapor)
N2 (nitrogen)
O2 (oxygen)
Visible Photons
Which three gases contribute to the greenhouse effect in our
atmosphere?____________________________
Which two gases do NOT contribute to the greenhouse effect?
_______________________________________
Analysis:
1. 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. If you were a weather person, how might you use what you understand
about clouds and the effect on temperature to predict night-time weather
for a summer month like June?
2. 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.
Extension: (Phase 3 only) Discover when the “Ice Age” was and what was has
changed about the composition of the greenhouse gases. Include cites for your
answers. How did the sim developers use this research information in the sim design?