Solarization refers to a phenomenon in physics where a material undergoes a temporary change in color after being subjected to high energy electromagnetic radiation, such as ultraviolet light or X-rays. Clear glass and many plastics will turn amber, green or other colors when subjected to X-radiation, and glass may turn blue after long term solar exposure in the desert. It is believed that solarization is caused by the formation of internal defects, called color centers, which selectively absorb portions of the visible light spectrum. Solarization may also permanently degrade a material's physical or mechanical properties, and is one of the mechanisms involved in the breakdown of plastics within the environment.
The term solarization is also used to describe sterilisation of soil or plant material by cooking the material in a plastic bag. In this case the sun's radiation is converted to heat by absorption, heating the material above 60 C, which kills off most harmful pathogens. The UV in the light may also have a germicidal effect on the surface material.