Ultraviolet

Ultraviolet is electromagnetic radiation with wavelengths shorter than visible violet light and longer than X-rays. Its photons can drive chemical reactions and damage biological tissue.

Electromagnetic spectrum: The full range of electromagnetic radiation, ordered by frequency or wavelength. Ultraviolet occupies the region between visible light and X-rays.
Ultraviolet germicidal irradiation: The use of short-wavelength ultraviolet radiation to inactivate microorganisms. UV-C damages microbial genetic material, enabling disinfection of air, water, and surfaces.
UVA: Ultraviolet radiation with wavelengths of about 315 to 400 nanometers. UVA is the longest-wavelength ultraviolet band and penetrates deeply into skin.
DNA photodamage: Molecular damage to DNA caused when absorbed light energy alters its chemical structure. Ultraviolet can form DNA lesions that lead to mutations if unrepaired.
Ultraviolet wavelength: The wavelength interval conventionally assigned to ultraviolet radiation, roughly 10 to 400 nanometers. Its boundaries distinguish ultraviolet bands and explain their different interactions.
Ultraviolet astronomy: The study of astronomical objects through their ultraviolet emissions. Hot stars and energetic gas often emit strongly at ultraviolet wavelengths.
UVB: Ultraviolet radiation with wavelengths of about 280 to 315 nanometers. UVB drives sunburn and directly damages DNA more efficiently than UVA.
Skin cancer: A group of cancers arising from cells in the skin. Cumulative ultraviolet exposure is a major preventable risk factor.
Photon: A quantum of electromagnetic radiation that carries energy and momentum. Ultraviolet photons carry more energy than visible-light photons.
Fluorescence: Light emission by a substance after it absorbs radiation, typically at a longer wavelength. Ultraviolet excitation makes otherwise hidden fluorescent materials visible.

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