the action of natural atmospheric conditions on any material exposed to them. Includes both physical disintegration and chemical decomposition caused by the elements; of rock and rock mantle mainly by temperature extremes, solution, and hydrolysis; of timber mainly by moisture changes causing alternate shrinking and swelling by oxidation, and by the erosive effects of rain, hail and wind-blown particles of dust and sand. Does not include fungal decay., the combined detrimental influences of the outdoor environment (for example sunlight, ozone, oxygen, humidity, temperature) on a material