By using a temperature sensor, we can relate changes in sunlight to the temperature of the air being trapped in a container.

How is the atmosphere like a greenhouse?

The greenhouse effect is the name scientists use to describe how heat can build up in the earth’s atmosphere.

A majority of the energy from the sun arrives at the earth as visible radiation. This energy passes through our atmosphere and warms the surface of the earth. The warmed surface re-emits radiation but this radiation is not visible as it is in the infrared. Some of this infrared radiation is absorbed by our atmosphere. Our atmosphere absorbs more of the infrared radiation when water vapor, carbon dioxide, and methane are present. The more readily the infrared is absorbed, the greater the net energy gain from sunlight.

The effect of this process was examined using a model in the Greenhouse gases activity. In this activity you will measure the phenomenon in a real greenhouse setting. A glass enclosure — a real greenhouse — works in the same way as the atmosphere to capture heat from sunlight.

• temperature sensor
• clear plastic food container without lid
• plastic wrap (large enough to cover the container)
• rubber band
• awl or scissors (to make a hole in plastic container)
• dirt
• clock

This activity addresses NSES standards for earth and space science and inquiry at grades 5-8
(http://books.nap.edu/readingroom/books/nses/6d.html#es).

• Caution: Do not look directly at the sun or a sun lamp as eye damage will result.
• Care should be taken while punching the hole in the plastic food container with the awl or scissors so no injury will result.

1. Obtain a clear plastic food container without a lid. Any size and shape container will do as long as the container’s width is larger than the metal portion of the temperature probe. The container shown just happens to be round.
2. Place a small amount of dirt in the bottom of the container.
3. Have an adult punch a small hole halfway up the side of the plastic food container. Place the temperature sensor through the side of the container.
4. Prepare a clear plastic wrap cover that will be held on by a rubber band.

Ordinary glass or clear plastic will transmit light but absorb infrared radiation. Knowing this, predict what will happen to the temperature under these two conditions:

a) container in sunlight without the cover;
b) container in sunlight with the plastic cover.

Draw your prediction on the graph below. Imagine that you will collect temperature data in sunlight for 20 minutes. For the first 10 minutes the container will have no cover. For the second 10 minutes the container will be covered with plastic. If you are indoors, the sun will be replaced by a bright light. Make the same prediction for that situation. You will need to move the time axis to include 1200 seconds (20 minutes) by clicking and dragging on the axis.

1. Place your container outside in direct sunlight or inside under a bright light.
2. Collect temperature data for 10 minutes with no cover.
3. Cover the container with plastic wrap.
4. Continue to collect temperature data for at least 10 more minutes.
5. You can repeat the experiment and save more datasets on the same graph, using the buttons on the left.

1. How did the temperature change inside your container with no cover?
2. What caused the change in temperature, if any?
3. How did the temperature change after the cover was put on?
4. What caused the change in temperature, if any?
5. How is this situation like the atmospheric “greenhouse effect”? How is it different?

Try the same experiment with a light-colored material in the container, such as sand or sugar or salt. Does it make a difference? Why?

• How would the readings change throughout a complete day (24 hours)?
• What if the surface was more reflective? You were using a dark (dirt) surface, now try a light (sugar) surface.
• What would happen if you added other materials to your container like plants or pollutants, etc.?
• How would an atmosphere of another color affect the temperature within the container?