That is dynamic soaring [1] which is I guess a subset of slope soaring, and is pretty rare and nuts. It generally requires flying in the lee of a slope rather than in front of it.

Regular slope soaring is relatively more sedate, fun and accessible if you have the right slope.

[1] https://en.wikipedia.org/wiki/Dynamic_soaring

> Dynamic soaring is sometimes confused with slope soaring which is a technique for achieving elevation.