Radiant energy incident to the earth’s surface in direct and diffuse components can be categorized in different wavelength bands of ultraviolet (UV), visible and infrared (IR). Radiometric quantities, definitions and equations are presented. Climate plays a key role in degradation processes. Different climates will affect materials in varying ways. The two benchmarks for weathering studies include subtropical and desert climates. This paper will also discuss how several answers may be obtained and decisions made during a test or in the evaluation of its results.
Other responses to the survey included the need to compare materials to competitors, presumably to facilitate sales and marketing campaigns for a company. While almost all testing is in some way related to research and development, about 10% of the testing done was strictly for these purposes, while another 10% tested to ensure that their material would meet warranty claims, or other requirements.