U

Ultraviolet (UV) radiation

Ultraviolet (UV) radiation: A type of electromagnetic radiation that is produced by the sun. UV radiation is not visible to the naked eye. Most UV radiation is blocked by ozone high in the Earth's atmosphere, but some of it reaches the Earth’s surface. Being exposed to too much UV radiation can cause a sunburn, and over time it can lead to skin cancer and eye damage. Too much UV radiation can also harm plants.