Hill
soaring can result when the wind blows up the side of a hill or at right
angles to a ridge (creating ridge lift). Some steep ridges provide a
powerful updraft that a glider use to gain significant height by soaring
parallel to the ridge, turning at each end as appropriate. The updraft
normally extends well above the top of the hill or ridge.
In particular conditions, wind over mountains can produce more powerful lift called wave. I experienced hill soaring on my first flight.
More about hill soaring later...