Sastrugi breaking equipment—ripples and waves are often undercut and the surface is hard and unforgiving, with constant minor topographic changes between ridge and trough. The words "sastrugi" and "zastrugi" are Russian-language plurals; the singular is "sastruga" or "zastruga". The form "sastruga" started as the German-language transliteration of the Russian word заструга (plural: заструги). A Latin-type analogica singular "sastrugus" is used in various writings on exploration of the South Pole, including Robert Falcon Scott's expedition's diaries and Ernest Shackleton's "The Heart of the Antarctic". Under the action of steady wind, free snow particles accumulate and drift like the sand grains in barchan
Surface wave detection by animals 14 cm. As the wave source gets farther from a fish, the fish’s ability to accurately determine distance decreases until it can no longer detect the waves. "A lineatus" uses the shape of the waveform to determine distance by analyzing how much the waveform has changed since it was generated; this amount of change is extremely predictable and regular. The surface waveform has high frequencies near source, and lower frequencies farther away due to the dampening effect of the water surface; the amount of decrease diminishes with distance. "A lineatus’" possible use of the wavefront’s curvature can be excluded since