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
Tropical wave tropical waves can extend northward as far as the desert southwest of the United States, producing spells of intensified shower activity embedded within the prevailing monsoon regime. A screaming eagle is a tropical wave whose convective pattern loosely resembles the head of an eagle. This phenomenon is caused by shearing from either westerly winds aloft or strong easterly winds at the surface. These systems are typically located within 25 degrees latitude of the equator. Rain showers and surface winds gusting to are associated with these waves. They move across the ocean at a rate of . Strong thunderstorm activity can