Investigate atmospheric greenhouse effect

Interactive Activity

 

Objective

Using a simulation, apply the scientific method to investigate the atmospheric greenhouse effect and its role in atmospheric energy transfer.

Background Reading

Before attempting the activity, review The Greenhouse Effectin Chapter 19 ofThe Sciences, as well as the website(NASA), to gain some background on the atmospheric greenhouse effect and its role in both atmospheric warming and climate change. The video(YouTube, 1:24) provides a short descriptive summary of the important points.

Introduction to the Simulation

1.After completing the background reading for this assignment, go to The Atmospheric Greenhouse Effect simulation on the PhET simulations website at: https://phet.colorado.edu/en/simulation/legacy/greenhouse. Click theplayarrow on the simulation graphic to run the web-based simulation or clickDOWNLOADto run the simulation locally on your device.

Simulation requirements:This interactive simulation isoptimized for use on computers (MACs or PCs) and may not run on some tablets, notebooks, cell phones, or other devices. Running the simulation will require an updated version ofsoftware (free). If you do not or are not sure if you have Java on your computer, go to.If you cannot get the simulation to run, consultThe PhET Simulation Troubleshooting Guideon the course website.

2. Explore and experiment on the three different tabs (areas) of the simulation. While experimenting, think about how the energy transfer processes involved in the atmospheric greenhouse effect are being visualized in the simulation.

Greenhouse effect tab Observe the effects of greenhouse gases on both incoming (solar) radiation and outgoing terrestrial (infrared) radiation and atmospheric temperature. Yellow stars simulate photons of incoming solar energy (visible radiation), while red stars simulate photons of outgoing terrestrial energy emitted from Earths surface (infrared radiation). The termphotondescribes a packet of electromagnetic radiation. You can simulate atmospheres with different concentrations of greenhouse gases at different times in Earths history, or manually adjust the concentration of greenhouse gases, and observe the effect on atmospheric temperature.Cloudsmay also be virtually placed in the atmosphere to observe their effects on air temperature.

 

Glass layers tab Create a greenhouse by adding glass panes to the atmosphere and observing the effect of a virtual glass ceiling on atmospheric temperature.

 

Photon absorption tabExperiment to determine the preference of different atmospheric gas molecules to absorb a certain type of radiation by shooting infrared or visible radiation at the molecules.

 

3. After getting oriented to the simulation, follow the steps below to perform four different experiments.Before beginning, be prepared to write down hypotheses and observations for the experiments.

Experiments

 

Experiment 1: The Atmospheric Greenhouse Effect and Temperatures Through History

In this experiment, you will observe the atmospheric greenhouse effect and how different concentrations of greenhouse gases at different times in Earths history affected atmospheric temperature.

Before completing the experiment,write down ahypothesis,based on your current understanding, that predicts the correlation between the concentration of greenhouse gases in the atmosphere and atmospheric temperature.

1.Experiment setup:click on theGreenhouse Effecttab at the top of the simulation screen.

2.Experiment procedure:

a. ClickReset Allat the bottom right of the screen. ClickYesin the box that pops up.

b. In theGreenhouse Gas Compositionbox, move the slider tonone. The simulation will run automatically for an atmosphere withnogreenhouse gases.

c. As the simulation runs, carefully observe the number and paths of bothsunlight photons(also called solar, or visible radiation) andinfrared photons(also called terrestrial, or infrared radiation), and the change in temperature on thethermometer. If needed, slow the simulation down in order to accurately observe what is happening.Write down your observations.

d. Allow the simulation to run until the thermometer settles on a temperature (when the atmosphere reachesequilibrium).Record this temperature.This is the equilibrium temperature of an atmosphere withnogreenhouse gases orclouds. Note that the temperature may fluctuate slightly once it reaches equilibrium, so do not be concerned about the exactness of your recorded temperature.

e. Click the button forTodayin theAtmosphere During…box.The simulation will now illustrate the atmospheric greenhouse effect and resulting atmospheric temperature for todays atmosphere.

f. As the simulation runs, again carefully observe the number and paths of bothsunlight photonsandinfrared photons, and the change in temperature on the thermometer. If needed, slow down the simulation in order to accurately observe what is happening. Note the difference in photon paths for the atmosphere with greenhouse gases compared to without.Write down your observations.

g. The greenhouse gases in the atmosphere are:water vapor (H2O), carbon dioxide (CO2), methane(CH4),andnitrous oxide (N2O).PPM is the abbreviation for parts per million.Record thegreenhouse gas compositionvalues forCO2, CH4,N2O, andH2O.

h. Allow the simulation to run until the thermometer settles on a temperature (when the atmosphere reachesequilibrium).Record this temperature.Note that the temperature may fluctuate slightly once it reaches equilibrium, so do not be concerned about the exactness of your recorded temperature.

i. Click the button next toIce Agein theAtmosphere During…box. The simulation will now illustrate the atmospheric greenhouse effect and resulting atmospheric temperature during an ice age.

j. Repeat the above stepsf through hto make observations and record the equilibrium temperature for the atmosphere during an ice age.

 

Experiment 1 – Results and Conclusions

1. Based on your observations while conducting the experiment, formulate a written discussion that describes the effect of

a. The atmosphere (with or without greenhouse gases) on incoming energy from the sun

b. Atmospheric greenhouse gases on outgoing Earth energy

2. Compare the observed values of equilibrium temperature for each of the simulated atmospheres in Experiment 1. Then, formulate a written statement that generalizes the effect of greenhouse gases on the atmospheres equilibrium temperature.

 

Experiment 2: The Effect of Clouds on Atmospheric Temperature

In this experiment, you will observe the effect of clouds on atmospheric temperature.

Before completing the experiment,write down ahypothesis,based on your current understanding, that predicts the effect of clouds on atmospheric temperature.

1.Experiment setup:click on theGreenhouse Effecttab at the top of the simulation screen.

2.Experiment procedure:

a. Repeat stepsa through dinExperiment 1. (Note that the equilibrium temperature should be the same as the one recorded in step d of Experiment 1).

b. In theOptionsbox next toNumber of Clouds, placethree cloudsinto the atmosphere by clicking theuparrow three times, so that3is showing.

c. As the simulation runs, carefully observe the number and paths of bothsunlight photonsandinfrared photons, as well as the change in temperature on the thermometer. If needed, slow down the simulation in order to accurately observe what is happening.Write down your observations.

d. Again, allow the simulation to run until the thermometer settles on an equilibrium temperature. This is the equilibrium temperature of an atmosphere withnogreenhouse gases andwithclouds.Record this temperature.

 

Experiment 2 – Results and Conclusions

1. Based on your observations while conducting the experiment, formulate a written discussion that describes the effect of clouds on

a. Incoming energy from the sun

b. Outgoing Earth energy

2. Develop a written statement describing the effect of clouds on the equilibrium temperature of the atmosphere.

 

Experiment 3: Glass Layers

In this experiment, you will observe what happens to the air temperature in arealgreenhouse, by placing virtual glass panes in the atmosphere.

Before completing the experiment,write down ahypothesis,based on your current understanding, that predicts the effects of the glass panes on atmospheric temperature.

1.Experiment setup:click on theGlass Layerstab at the top of the simulation screen.

2.Experiment procedure:

a. ClickReset Allon the right side of the screen. The simulation will start running automatically for an atmosphere withnogreenhouse gases andnopanes of glass in the atmosphere.

b. As the simulation runs, carefully observe the number and paths of both sunlight photons (visible radiation) and infrared photons (terrestrial radiation), and the change in temperature on the thermometer. If needed, slow the simulation down in order to accurately observe what is happening.Write down your observations.

c. Allow the simulation to run until the thermometer settles on an equilibrium temperature. This is the equilibrium temperature of an atmosphere withnogreenhouse gases or glass panes.Record this temperature.(It should be the same as the one recorded in step d of Experiment 1.)

d. In theOptionsbox, next toNumber of Glass Panes, placeone glass paneinto the atmosphere by clicking theuparrow once so that1is showing.

e. Repeatstep babove.

f. Again, allow the simulation to run until the thermometer settles on an equilibrium temperature. This is the equilibrium temperature of an atmosphere withnogreenhouse gases andone glass pane.Record this temperature.

 

Experiment 3 – Results and Conclusions

1. Based on your observations while conducting the experiment, formulate a written discussion that describes the effect of glass panes on

a. Incoming energy from the sun

b. Outgoing Earth energy

2. Based on your discussion above, explain why the termgreenhouseis used to describe the effect of atmospheric gases, such as carbon dioxide and water vapor, on atmospheric temperature.

NOTE:If you are not entirely sure of the meaning of the termgreenhouse, do some research on the topic before formulating your explanation.

 

Experiment 4: Photon Absorption

In this experiment, you will determine which gases in our atmosphere are greenhouse gases by shooting photons of both visible and infrared radiation at gas molecules and observing their reaction.

Before completing the experiment,write down ahypothesis,based on your current understanding, that predicts how each gas molecule will react when photons of visible or infrared energy are shot at it.

1.Experiment setup:click on thePhoton Absorptiontab at the top of the simulation screen.

2.Experiment procedure:

Construct a table like the one below. Complete the following steps to complete the table.

a. Click the button next toCH4in theAtmospheric Gasesbox. A methane gas molecule now sits in the middle of the screen.

b. Click the button next toInfrared Photon,underneath the photon gun.

c. Using the slider underneath the gun, shoot 50 infrared photons at the molecule at aslow enoughspeed that allows you to observe what is happening while counting off the 50 photons at the same time.

d. As photons are emitted from the gun, observe that some of the photons pass through the molecule, and some are absorbed by the molecule. It will be obvious when a photon is absorbed by the molecule. As you count off the 50 photons,make a tick mark on a piece of paper each time a photon is absorbed.

e. Out of the 50 photons shot at the molecule,tally up the number of photons thatwere absorbedby the molecule, and record this value.

f. With the gun still loaded withinfrared photons,repeat stepsc through eabove for the other four gases in theAtmospheric Gasesbox –CO2, H2O, O2 and N2.

g. Click the button next toVisible Photon,underneath the photon gun, to load the gun with visible photons to shoot at the gas molecules.

h. With the gun now loaded withvisible photons, repeat stepsc through eabove forallfive of the gases in theAtmospheric Gasesbox –CH4, CO2, H2O, O2 and N2.

Gas Molecule	# of Infrared Photons Absorbed (out of 50)	# of Visible Photons Absorbed (out of 50)
CH4 (methane)
CO2 (carbon dioxide)
H2O (water vapor)
O2 (oxygen)
N2 (nitrogen)

 

Experiment 4 – Results and Conclusions

1. Basedonlyon your observations while conducting the experiment, formulate a written discussion that describes howoxygenandnitrogen(the two primary components of Earths atmosphere) interacted with both incoming solar radiation and outgoing Earth radiation.

2. Basedonlyon your observations while conducting the experimentandthe known properties of a greenhouse gas:

a. Identify which gases tested are greenhouse gases and explain how this was determined.

b. Identify whichoneof the gas tested is the most effective at doing its job as a greenhouse gas and explain how this was determined.

Activity Submission

1.Create a document containing a report for each experiment. Your document should contain four paragraphs, one for each experiment.

a.Title each paragraph with the corresponding name for each experiment, as it is stated in the headings for the experiments above (e.g., Experiment 1: The Atmospheric Greenhouse Effect and Temperatures Through History).

b. For each experiment report:

i. Clearly and succinctly present your hypothesis for the experiment.

ii.Based on the information prompted for in the experimentsProcedureandResults and Conclusionssection, clearly and succinctly summarize your observations, results, and conclusions for the experiment, and include any data collected and calculations made.

iii.Clearly and succinctly evaluate the correctness of your hypothesis based on the information presented in part ii above.

c. Include your full name and the date you completed the activity at the top of the document.

 

2. Submit your document (in either.docx or .pdffileformat) as instructed in the assignment location within the Canvas course.