Here's why:
* Mountains create rain shadows: The windward side of a mountain (the side facing the wind) receives the most precipitation. As air rises over the mountain, it cools and condenses, releasing rain or snow. By the time the air reaches the leeward side (the other side of the mountain), it's drier, creating a "rain shadow."
* The "dry side" can still get precipitation: While the leeward side generally receives less precipitation than the windward side, it's not always completely dry. Factors like the overall climate, the height of the mountain, and the direction of prevailing winds can influence precipitation patterns on both sides.
So, instead of a specific term, it's more accurate to talk about the windward (wetter) and leeward (dryer) sides of a mountain, even if the leeward side receives some precipitation.