Sastrugi dunes, and the resulting drifting snow shapes are also popularly referred to as "barchans". Inuit of Canada call them "kalutoqaniq". When winds slacken, the drifted formations consolidate via sublimation and recrystallization. Subsequent winds erode kalutoqaniq into the sculptured forms of sastrugi. Inuit call large sculpturings "kaioqlaq" and small ripples "tumarinyiq". Further erosion may turn "kaioqlaq" back into drifting "kalutoqaniq". An intermediate stage of erosion is "mapsuk", an overhanging shape. On the windward side of a ridge, the base erodes faster than the top, producing a shape like an anvil tip pointing upwind. Sastrugi are more likely to form on first-year
Surface wave Zenneck–Sommerfeld surface wave, the trapped surface wave and the gliding wave. See also Dyakonov surface waves (DSW) propagating at the interface of transparent materials with different symmetry. Lower frequency radio waves, below 3 MHz, travel efficiently as ground waves. In ITU nomenclature, this includes (in order): medium frequency (MF), low frequency (LF), very low frequency (VLF), ultra low frequency (ULF), super low frequency (SLF), extremely low frequency (ELF) waves. Ground propagation works because lower-frequency waves are more strongly diffracted around obstacles due to their long wavelengths, allowing them to follow the Earth's curvature. The Earth has one refractive index and