Why is it called the “greenhouse” effect?

The greenhouse effects gets its name from agricultural greenhouses, which also trap heat. In that sense, the name “greenhouse effect” is a good name, because both greenhouses and the greenhouse effect trap heat and keep something (the greenhouse or the planet) warmer than it would be otherwise. However, the precise way in which the greenhouse effect traps heat is a bit different from that of a greenhouse. Greenhouses stay warm primarily by preventing warm air from escaping them. In contrast (and as shown in Figure 7.1.1–4), the greenhouse effect warms a planet by slowing the escape of infrared light, not by suppressing the movement of air.