Sastrugi Sastrugi Sastrugi, or zastrugi, are sharp irregular grooves or ridges formed on a snow surface by wind erosion, saltation of snow particles, and deposition, and found in polar and open sites such as frozen lakes in cold temperate regions. The ridges are usually perpendicular to the prevailing winds; they are steep on the windward side and sloping to the leeward side. Smaller irregularities of this type are known as ripples (small, ~10 mm high) or wind ridges. Larger features are especially troublesome to skiers and snowboarders. Traveling on the irregular surface of sastrugi can be very tiring, and can risk
Surface wave detection by animals ridges; this was shown with electrophysiology. The same experiment also showed that adding ridges to neuromasts that did not previously have ridges also altered the receptive fields for those neuromasts. This suggests that local water flow is important in direction detection. "A lineatus" and other surface wave detecting fish have a limited range in which they can detect surface waves. The ratio of source distance/swim distance ranges between 0.84 and 1.20, and the means range from 0.98 to 1.07. This translates to an accuracy of 85% or higher when stimuli are 6–19 cm from the fish, decreasing to 76% at