Climate in a Jar

Purpose:

To observe the greenhouse effect in a direct, hands-on way. To consider experimental design and other physical principles that contribute to energy transfer.

Materials:

3-12 Glass, 1 quart canning jars

Plastic Wrap

Rubber Bands or Metal Rings

2 Heat Lamps of equal intensity (to provide infrared energy)

3-12 Thermometers that fit inside glass jars

Optional:

Lighters/matches, sodium bicarbonate (baking soda, NaHCO₃) and acetic acid (vinegar, CH₃COOH), water, salt, small plants, wood, paper, or other sources of carbon dioxide, methane, oxygen, or variables to experiment

Method:

Simple Version

1. Place two open jars side by side, and put thermometers that read the same temperature inside them. Be careful not to lay the thermometers so they touch the glass. Note the temperature on each. 

2. Introduce a source of carbon dioxide or methane to one of the jars and seal it with plastic wrap quickly. This can be either exhaling into the jar, using dry ice gas, using baking soda and a tiny bit of vinegar, burning a small piece of wood or paper, or using decaying vegetation.

3. Leave the Control jar open. Allow both jars to come to the same temperature (if using a warm source of carbon dioxide) and then place under heat lamps at the same distance, on their sides. Wait at least 2 minutes, or up to 5 minutes. 

4. Quickly remove and read the thermometers and note both temperatures. Jars with more carbon dioxide should read 2-6 degrees F *higher*.

Variables

1. You can try this experiment with adding carbon dioxide and a plant to “fix” the gas, or using water, salt water, and shaking the jars after carbon dioxide addition to see various effects of different natural combinations. 

2. Try to control for sources of error. Metal conducts heat faster than air, glass, or water, so be careful not to use metal lids, or determine if metal rings are causing difficulty. Exhaling will produce only small amounts of carbon dioxide, compared to burning organic matter or a chemical reaction with sodium bicarbonate and acetic acid. Thermometers absorb infrared heat from the lamps directly, so you may need to control for that by placing them upside-down on top of a strip of paper (so they don’t touch the glass). 

3. You can try this experiment under even, direct sunlight as well as lamps. The lamps will produce MORE infrared than actual sunlight (distance) but the same effect can be observed. 

4. If you get an unexpected result, analyze why that may have happened and how you can better control for variables.