Much of the sun's light passes through the earth's atmosphere and strikes the ground. The light that's reflected back up is often of a different wavelength than the incoming light. Climate Data Information explains that these wavelengths can be absorbed by molecules of greenhouse gases, which raises the temperature of the air. Water vapor, caused by evaporation, acts over a broad range of wavelengths. Carbon dioxide and methane are just as effective at absorbing energy, but over a shorter part of the spectrum.