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 that further analysis of waves must happen at higher levels in the nervous system. The African clawed frog ("Xenopus laevis") responds to surface waves. It is able to locate wave directions at least to within ± 5° and they can localize and distinguish between two different water waves coming simultaneously from two insects in different directions. Xenopus has approximately 200 lateral-line organs located along the sides of its body, and also around its eyes, head and neck. It is claimed these are used to navigate and detect prey either striking the water or struggling but the role of these organs