The type of rainfall caused by mountains in the way is called orographic rainfall.

Here's how it works:

1. Moist air mass: Air carrying moisture moves towards a mountain range.

2. Forced uplift: As the air mass encounters the mountain, it is forced to rise.

3. Cooling and condensation: As the air rises, it cools. Cool air can hold less moisture, so the water vapor in the air condenses into clouds.

4. Rainfall: The condensed water vapor falls as precipitation on the windward side of the mountain (the side facing the oncoming air).

This is why the windward side of a mountain range often experiences more rainfall than the leeward side.