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 and predictable waves, as dictated by surface tension and gravity. The water surface has a dampening effect which causes an abnormal dispersion pattern in which waves decrease in amplitude, speed and frequency with distance from the source. Short-wavelength (higher frequency) waves disperse faster than longer wavelength waves, resulting in higher frequencies at the front of the wave-train and lower frequencies at the tail; a fish detects this as a downward-sweeping frequency modulation. A vast amount of the research on surface wave detection has been done in the surface-feeding topminnow/killfish "Aplocheilus lineatus". Schwartz (1965) demonstrated that this species has exceptionally well-developed