Ridge Soaring
RIDGE SOARING
A number of different tactics are useful in ridge soaring. The most appropriate one for a given circumstance is dictated by the shape or size of a hill, and the idiosyncrasies of resulting airflow. A simple way to analyze hills for their utility in ridge soaring is to distinguish between sections of terrain that act as collectors and/or dividers. Slopes and bowls that more or less directly face the wind will collect it and concentrate any available lift. But slopes angled away from the wind, or protrusions into it, tend to deflect or divide the flow, either ruining lift or focusing the wind elsewhere. Which parts of a mountain function in which way depends upon the existing conditions – primarily wind strength and direction, plus countless other interrelated factors. Such relationships constantly shift with changes in weather and sun angle.
Even a concave feature that collects and concentrates wind from a broad area may not always produce good lift. Whether it’s a shallow indentation or an impressive canyon, changes in wind or sun angle can transform it from a terrific lift source to a deadly sinkhole – or the reverse – in less than an hour. A convex feature can be even more unpredictable. It may tend to divide wind flow, but if wide enough and oriented properly, might itself act as an individual ridge or thermal trigger. Depending on other surrounding influences, a particular mountainside could even switch back and forth from one effect to the other every few minutes.A number of different tactics are useful in ridge soaring. The most appropriate one for a given circumstance is dictated by the shape or size of a hill, and the idiosyncrasies of resulting airflow. A simple way to analyze hills for their utility in ridge soaring is to distinguish between sections of terrain that act as collectors and/or dividers. Slopes and bowls that more or less directly face the wind will collect it and concentrate any available lift. But slopes angled away from the wind, or protrusions into it, tend to deflect or divide the flow, either ruining lift or focusing the wind elsewhere. Which parts of a mountain function in which way depends upon the existing conditions – primarily wind strength and direction, plus countless other interrelated factors. Such relationships constantly shift with changes in weather and sun angle.Even a concave feature that collects and concentrates wind from a broad area may not always produce good lift. Whether it’s a shallow indentation or an impressive canyon, changes in wind or sun angle can transform it from a terrific lift source to a deadly sinkhole – or the reverse – in less than an hour. A convex feature can be even more unpredictable. It may tend to divide wind flow, but if wide enough and oriented properly, might itself act as an individual ridge or thermal trigger. Depending on other surrounding influences, a particular mountainside could even switch back and forth from one effect to the other every few minutes.As a slope changes shape beneath the onrushing sailplane, you’ll need to make adjustments on a moment-by-moment basis. For example, even a small protrusion lying upwind, lower than the slope you’re on, may interrupt lift a mile or more downwind – and potentially thousands of feet higher. If you come upon such a disturbance and have enough altitude or speed to sail across it, you can probably expect a return of dependable lift just beyond. But some hills are so low that a loss of three or four hundred feet means landing out, and the critical decision whether to continue or turn back must be timely. Study the route ahead before flying close to hills of any kind, and continually use imagination to anticipate how the air will flow.It’s usually best to attack the nearest or highest point within reach first, and then explore progressively higher ground as you climb – or lower peaks if you fail to maintain height. A high, steep slope may sometimes provide good lift well below the crest, making it possible to arrive there low and gradually climb. But if instead you lose altitude, the slope encroaching from below will continually shrink your usable airspace. So, the closer you are to terrain that extends above you, the more important it is to either climb or get away.