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 detection by animals to test certain wave properties. Wave characteristics are measured optically. This is done by shining a laser (often helium-neon) at the water surface. Reflections and distortions of the laser’s beam are picked up by a photodiode. Fishes' movements are videotaped with a high-speed camera from above the testing tank so that the precise timing and nature of their responses’ to stimuli can be reviewed. "Aplocheilus lineatus" assumes a hunting posture at the water surface in which it holds the top of its head within 200 μm of the water surface. On perception of appropriate wave stimuli, fish first turn towards