Water vapor or moist air rising over a mountain will cool and precipitate as rainfall.
As water vapor, or moist air approaches a mountain, it will rise because the mountains are in the way. The higher you go up a mountain the colder it becomes. Because of the colder temperature up the mountain, the moist air will cool down to reach what is known as its dew point. The moisture in that air then condenses into clouds and eventually, rain. This is why the heaviest rain occurs on the windward slope of a mountain.
What happens to water vapor as it rises over the mountain is it will cool and precipitate as rainfall.
<h3>Further explanation</h3>
Water vapor is the gaseous phase of water and it is one state of water within the hydrosphere. It can be produced from evaporation or liquid water boiling or from the ice sublimation. As water vapor rises over the mountain is it will cool and precipitate as rainfall. Air forced to rise over a barrier of mountains or hills. Rain itself is the liquid water in droplets form that condensed from atmospheric water vapor and become heavy enough to fall under gravity. It is a major component of the water cycle and it is responsible for depositing most of the fresh water on the Earth.
If a air volume contains the maximum amount of water vapor and the temperature is decreased, then some water vapor will condense to form liquid water. Then the clouds form as warm air containing water vapor rises and cools at higher altitudes. These water droplets gather to form clouds and precipitation.
