Beyond the visible spectrum, sunlight emits ultraviolet radiation with wavelengths shorter than 380nm – commonly referred to as UV – and infrared radiations with wavelengths greater than 780nm. Ultraviolet radiation arriving on earth surface is divided into UVB (280-315nm) and UVA (315-380nm). At sea level, about 10 percent of radiation is UV, 50 percent is visible and 40 percent is infrared