The low-precipitation area on the leeward side of a mountain range is called a rain shadow.

Here's why:

* Windward Side: When moist air rises up the windward side of a mountain range, it cools and condenses, leading to precipitation.

* Leeward Side: The air that descends the leeward side has already released most of its moisture. This dry air creates a "shadow" of low precipitation on the other side of the mountain.