Final answer:
The windward side of a mountain is more fertile than the leeward side due to increased precipitation caused by moist air rising over the mountain range and condensing. The leeward side experiences a "rain shadow" with less precipitation, resulting in less fertility.
Step-by-step explanation:
The windward side of a mountain is more fertile than the leeward side due to increased precipitation. When moist air from the ocean rises up over a mountain range, it cools and its water vapor condenses, causing precipitation to fall on the windward side. On the other hand, the air on the leeward side is dry, leading to little precipitation and creating a "rain shadow." This difference in precipitation levels contributes to the windward side being more fertile.