Climate Change weather, compared

The National Academy issued its report on 12 June 1956. In some ways its findings were reassuring. Contrary to widely circulated speculation, it denied that nudear-bomb tests had caused discernible changes in climate or weather conditions. In its assessment of the effects of radioactive fallout, the study concluded that the amount of radiation produced by weapons tests to that time did not present a major health hazard. Compared with the exposure the U.S. population received firom X rays and from natural background radiation that comes from cosmic rays and radioactive substances in rocks and the soil, the doses from fallout were small. The report also declared "It appears that radiation problems, if... 

How well can we predict long-term effects Because weather has been studied for a period of time that is minuscule compared with the age of the earth, the factors that control the earth s climate in the long range, such as changes in the sun, are not clearly understood. For example, we do not understand what causes the earth s periodic ice ages. So it is difficult to estimate the impact of the increasing carbon dioxide levels. 

A number of studies have been conducted to investigate how well SLP accomplishes these goals for selected polymer-based materials [1 ]. From these, reasonable estimates of lifetime were obtained as compared to actual values of time to failure observed for outdoor exposures. Some of the predictions covered the entire degradation pathway, for which changes in material properties generally followed a trend similar to that measured during outdoor weathering. The SLP methods employed varied somewhat from study to study and all used measured climate data to test their models. 

Accelerated aging is achieved in artificial weathering by increased loads compared with outdoor weathering (e.g., radiation intensity). Here, the number of simulated climate factors is reduced (e.g., night and winter periods are neglected) or their cyclic change is neglected (e.g., temperature and humidity variations) [208]. 

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