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 as 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.