Útfjólublá

Útfjólublá, often abbreviated as UV, refers to electromagnetic radiation with a wavelength shorter than visible light but longer than X-rays. It occupies a portion of the electromagnetic spectrum ranging from approximately 10 nanometers to 400 nanometers. Sunlight is a primary source of UV radiation, though artificial sources like tanning beds and germicidal lamps also emit it.

UV radiation is categorized into three main types based on wavelength: UVA (315-400 nm), UVB (280-315 nm), and UVC (100-280 nm). The Earth's ozone layer effectively absorbs most UVC and a significant portion of UVB radiation, meaning that the UV reaching the surface is predominantly UVA and some UVB.

The effects of UV radiation on biological organisms are varied. In humans, moderate exposure to UVB is essential for the synthesis of vitamin D, which plays a crucial role in bone health. However, excessive exposure can lead to detrimental effects such as sunburn, premature skin aging, and an increased risk of skin cancer. UV radiation can also damage the eyes, potentially causing cataracts.

Industrially, UV light has applications in sterilization and disinfection due to its ability to kill microorganisms. It is also used in curing inks and resins, and in phototherapy for certain skin conditions. The study of útfjólublá is a significant area within physics and atmospheric science.