Basic Requirements
Ridge lift is generated when the wind blows against a hill, ridge, escarpment or ocean wave, causing the air to rise. In meteorology this is known as orographic lift. The wind creates a region of rising air directly above the slope which may extend some distance upwards and outwards from its face because the airflow follows the upward contour of the hill. However at near vertical cliffs, there is usually an area of turbulence with descending air near the base of the cliff. Downwind of the hill, lee waves can form that are also used by glider pilots to gain height but this should not be confused with slope lift.
Near slopes rather than vertical cliffs, the strongest lift is often to be found a flight path that intersects with an imaginary line emerging at right angles from the slope.
Long mountain ranges such as those found in Ridge-and-valley Appalachians in the United States, New Zealand, and Chile have been used by glider pilots to fly in excess of a thousand kilometers in a single flight. Birds, such as many seabirds (in particular albatross) and raptors, also use slopes in this way.
Read more about this topic: Ridge Lift
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