19308

This article contains a common misconception about the greenhouse effect. It states, “The newly detected gas is chemically similar to sulfur hexafluoride–another strong absorber of solar radiation . . .” (emphasis mine). While this statement may be true, it is irrelevant to the greenhouse efficiency of a gas. The mechanism of the greenhouse effect involves absorption of terrestrial radiation. A greenhouse substance admits incoming radiation, with its principal power density in the visible band, but stops the outgoing radiation, with its principal power density in the infrared band. This is why cars get so hot in the sun: The windows are transparent in the visible but not in the infrared.

Gerald A. Larson
Huntsville, Ala.