ULTRAVIOLET RAYS AND ITS ENVIRONMENTAL EFFECTS.

Ultraviolet radiation is one form of radiant energy coming from the sun. The various forms of energy, or radiation, are classified according to wavelength, measured in nanometers (one nm is a millionth of a millimeter). The shorter the wavelength, the more energetic the radiation. In order of decreasing energy, the principal forms of radiation are gamma rays, X rays, UV (ultraviolet radiation), visible light, infrared radiation, microwaves, and radio waves. There are three categories of UV radiation: 1. UV-A, between 320 and 400 nm 2. UV-B, between 280 and 320 nm 3. UV-C, between 100 and 280 nm The most dangerous solar radiations are the UV ones, such as: UV-A, UV-B, and UVC. Therefore, we must appreciate that the protective role of the ozone layer in the upper atmosphere is so vital that scientists believe life on land probably would not have evolved - and could not exist today - without it. description of the study and used methods. [ABSTRACT FROM AUTHOR]