Light from the sun; also called sunshine. The majority of the energy from the sun is divided into three parts: ultraviolet radiation, wavelengths less than about 0. 4 μm; visible radiation, wavelengths between about 0. 4 and 0. 7 μm; infrared radiation, wavelengths greater than about 0. 7 μm. There are conflicting conventions as to whether all three regions are referred to as light, or whether that term should only be applied to the visible portion of the spectrum. The ultraviolet radiation is sometimes called short waves and the infrared region, long waves.