We present an experiment investigating the physics of the atmospheric greenhouse effect that can be performed by undergraduate physics students. The students construct a three-channel spectral photometer to observe the infrared heat flux in the atmosphere. With this spectral photometer, the students observe the difference in heat flux between the portion of the IR spectrum that is absorbed by water vapor and carbon dioxide and the portion that is not absorbed by atmospheric constituents. The students discover that Earth's surface is warmed by radiation from the greenhouse gas absorption bands, and the radiation of heat to space is retarded by the absorption bands. One component of the experiment is performed on the ground and the other component is performed in the atmosphere using a high-altitude balloon. The students then compare their results to a simulation of infrared radiation transport in the atmosphere.

Supplementary Material

AAPT members receive access to the American Journal of Physics and The Physics Teacher as a member benefit. To learn more about this member benefit and becoming an AAPT member, visit the Joining AAPT page.