Caustic effects due to sunlight reflections from skyscrapers: simulations and experiments.

Reflections from glass fronts of curved shape buildings are discussed. Irradiance within the respective caustics can become quite large with regard to regular sun irradiance and can lead to thermal effects. These may cause problems as has been reported for some existing buildings. The phenomena are theoretically discussed for a variety of systems made of segments of cylindrical mirrors using ray tracing models. In particular, six parameters are varied which have an influence on the caustic: building height, building width, radius of curvature, building orientation as well as sun elevation and azimuth angles. In addition, experiments have been performed for various curved shape mirrors and smallscale models of an existing building, for which problems are known to exist. In particular, we investigated the resulting caustic forms visually as well as with infrared cameras to visualize respective thermal effects. Results can explain all features of reported problems. Providing a link to everyday life and modern architecture, the topic is suitable for introducing mirror optics experimentally at school and undergraduate aswell as theoretically at undergraduate and graduate level. [ABSTRACT FROM AUTHOR]