What happens when a prevailing wind reaches a mountain range?

When a prevailing wind meets a mountain, the mountain deflects the wind and causes it to flow parallel to the range. On low ranges and hills, strong up and down drafts occur as the wind goes up over the mountain and down into the valleys. If there is a pass in the mountain, the air rushes through at a considerable speed, causing turbulence for some distance as it rushes into the flatter land.