Atmospheric duct by the ionosphere. The reduced refractive index due to lower densities at the higher altitudes in the Earth's atmosphere bends the signals back toward the Earth. Signals in a higher refractive index layer, "i.e.," duct, tend to remain in that layer because of the reflection and refraction encountered at the boundary with a lower refractive index material. In some weather conditions, such as inversion layers, density changes so rapidly that waves are guided around the curvature of the earth at constant altitude. Phenomena of atmospheric optics related to atmospheric ducting include the green flash, Fata Morgana, superior mirage, mock mirage
Waves Radio annual Scottish Week celebrations. Following the success of the initial broadcasts the station returned every summer, with the introduction of additional broadcasts made over the Christmas periods in 1994 and 1995. The station ceased broadcasting in July 1996 and was unable to transmit over the festive period due to the announcement of the full-time licence. After gaining a full-time licence, Waves Radio launched on 6 December 1997, from its current studios at Blackhouse Circle. Glenn Moir is the stations news editor, responsible for producing the daily local news bulletins. These are broadcast at 8.30am, 12.30pm and 5.30pm Monday - Friday.