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Wave Soaring

Wave lift is found on the lee side of mountains. Crests of the wave are found at a distance between 5-50km from the top of the mountain. The mountain wave is often recognized by the presence of mountain cap clouds, roll (rotor) clouds, and lenticular clouds. Turbulence is often found at the crests and troughs where the air is unstable due to adiabatic heating and cooling. Most soaring pilots seek wave flights above 10,000 feet. In this area ground clues are not very useful. Often it is very difficult to pick out other aircraft, as there is very little contrasting background informa-tion. A white glider against the sky does not offer a very good target for the eyes. The transition in and out of the wave can be quite turbulent. While in the wave rates of climb can be quite dramatic, they are usually silky smooth. The subsequent rides down can leave surprisingly little time to make good decisions, especially when you are preoccupied with turbulence. While general visibility is usually good, there is increased hazard of the clouds forming either below or around aircraft quickly which presents a whole host of attendant dangers. At altitude we have a disparity between true and indicated airspeed, which cannot be sensed. Lee waves are ripples in the atmosphere downwind of obstructions. As is seen with a rock in a stream, this ripples have an upgoing and a downgoing part and underneath the crest of the waves are areas of turbulence. These waves generally require stable air capping a convective layer, and wind at different layers sharply contrasted. They are usually associated with cold fronts with cold air undercutting warm. Flying in mountain waves presents a number of hazards. Turbulence in the area of the rotor clouds can be quite severe. Clouds may form and obscure the ground and other obstructions. Navigation at these altitudes can be difficult as one can become disoriented easily. Strong winds aloft can also lead to navigation and glider performance misjudgements. Variable ground winds are often associated with wave conditions and can lead to dangerous landing conditions.. In the wave itself icing conditions can arise, affecting both the sailplane externally and internally in the cockpit. Oxygen systems are required. This represents another source for equipment failure not normally encountered in soaring.