Very low frequency the bottom of the ionosphere called the D layer at 60 to 90 km (37 to 56 miles) altitude, which reflects VLF radio waves. The conductive ionosphere and the conductive Earth form a horizontal "duct" a few VLF wavelengths high, which acts as a waveguide confining the waves so they don't escape into space. The waves travel in a zigzag path around the Earth, reflected alternately by the Earth and the ionosphere, in TM (transverse magnetic) mode. VLF waves have very low path attenuation, 2-3 dB per 1000 km, with little of the "fading" experienced at higher frequencies, This is
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