Very low frequency because VLF waves are reflected from the bottom of the ionosphere, while higher frequency shortwave signals are returned to Earth from higher layers in the ionosphere, the F1 and F2 layers, by a refraction process, and spend most of their journey in the ionosphere, so they are much more affected by ionization gradients and turbulence. Therefore, VLF transmissions are very stable and reliable, and are used for long distance communication. Propagation distances of 5000 to 20000 km have been realized. However, atmospheric noise (sferics) is high in the band, including such phenomena as "whistlers", caused by lightning. VLF waves can
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.