Occurs when the horizontal winds move air against mountain ranges, forcing air to rise as it passes over the mountains.

The answer would be:
Precipitation sometimes occurs when the horizontal winds move air against mountain ranges, forcing air to rise as it passes over the mountains.
This happens when the air is forced to move from low elevation to high elevation due to rising terrain. This causes the air to cool adiabatically. This increases the relative humidity and causes clouds to form, under certain conditions it can also create precipitation.