What Are Ultraviolet Rays?

Ultraviolet rays are undetectable light rays with a wavelength longer than that of x-rays and shorter than that of noticeable light. The name 'ultraviolet' in Latin means 'beyond violet.' Violet is the colour of the shortest wavelength in a visible spectrum of light. The UV light has a wavelength which is even shorter than the violet light.

Thus ultraviolet rays from the sun are actually radiation from the sun which falls in the invisible area of the spectrum. The sun sends out ultraviolet rays in the UVA, UVB and UVC bands, but thanks to the ozone layer in the atmosphere, 99 percent of the ultraviolet radiation that reach the earth's surface is UVA. UVA rays are beneficial for plant life. It can also be used in dentistry and certain forms of medical procedures. UVB light induces Vitamin D for the skin. However a long term exposure to UVA, UVB and UVC rays can cause premature ageing and even skin cancer. A medically approved sunscreen cream can effectively block both UVA and UVB.