Visible Light and Infrared Heat
- Hothouses can be made from a variety of materials, including glass, fiberglass and plastic. Radiation in the form of visible light passes through the walls of the hothouse and is absorbed by the plants, soil, rocks, planters and other objects in the hothouse. These objects also give off radiation, but in the form of infrared heat. Visible light can easily pass through glass but infrared heat cannot. This energy becomes trapped in the hothouse and raises the temperature inside.