"The sun produces its strongest electromagnetic radiation in the ultra-
violet (UV) and visible light portion of the spectrum.
In addition, the atmosphere lets most of the visible light (400–750 nm) through.
This allows our world to be illuminated, but it filters out the higher frequency UV radiation that is just outside the visible spectrum.
The radiation filtered out includes all the extremely harmful UV-C (100–280 nm) and most of the UV-B light (280–315 nm), excessive exposure to which causes sunburn and skin cancer." CMI