Inside the greenhouse the visible light is absorbed by the plants and soil and is converted into heat, which is then emitted by the plants and soil in form of infrared radiation. (scientificamerican.com)
But instead of allowing the waste heat to dissipate in the form of infrared radiation, secondary structures surrounding the filament capture this radiation and reflect it back to the filament to be re-absorbed and re-emitted as visible light. (sciencedaily.com)
All objects, including our bodies, throw off heat in the form of infrared radiation, an invisible and benign wavelength of light. (sciencedaily.com)