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
Rough Waves Shukei (), whose still-extant paintings include a number of dynamic and mysterious images of sea waves, among them "Egret, Moon, and Wave" and "The Wind and the Waves". "Rough Waves" also reflects the influence of Tawaraya Sōtatsu, who specialized in gloomy landscapes, but is nevertheless an independent interpretation by Ogata of the frightening and violent force of the sea. "Rough Waves" impressed Ogata’s follower Sakai Hōitsu, who in 1805 created his work "Waves", in which he tried to convey a similar frightening atmosphere and a premonition of danger. At some time in the past, Hōitsu's family had commissioned work from