Atmospheric refraction Atmospheric refraction is considered in measuring the position of both celestial and terrestrial objects. Astronomical or celestial refraction causes astronomical objects to appear higher above the horizon than they actually are. Terrestrial refraction usually causes terrestrial objects to appear higher than they actually are, although in the afternoon when the air near the ground is heated, the rays can curve upward making objects appear lower than they actually are. Refraction not only affects visible light rays, but all electromagnetic radiation, although in varying degrees. For example, in the visible spectrum, blue is more affected than red. This may cause astronomical
A/B Sound System eliminate the comb-filtering effect.” An A/B system is used in the Avon Theatre at the Stratford Festival in Canada. Stratford Festival sound designer William Fallon said, "I've found that it has also helped in creating separation and clarity in large production numbers, by being able to send half the cast down one path and the other half down another, either based on parts, blocking, leads vs ensemble, etc." A/B Sound System An A/B Sound System is a type of Sound reinforcement system or Public address system. Unlike a more typical sound reinforcement system, an A/B Sound System provides two electrically