Final answer:
Downslope winds flowing from high elevations to valleys are known as mountain or katabatic winds, and they are a key component of the rain shadow effect, which leads to arid conditions on the leeward side of mountains.
Step-by-step explanation:
The downslope winds that flow from high elevations down to valleys or plains are known as mountain or katabatic winds. These winds are part of a broader weather phenomenon that can result in dramatic changes in climate on different sides of mountain ranges, known as the rain shadow effect. The process begins when moist air from the ocean rises over a mountain range, cooling and condensing to bring precipitation to the windward side of the mountains. As the air mass passes over the top and descends on the leeward side, it becomes warmer and drier, leading to arid conditions in the valley below.