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What Happens to Air Containing Water Vapor?

All of the water on Earth is in constant motion, including water vapor in the air. The water cycle, sometimes called the hydrologic cycle, explains this movement. Within the water cycle, air containing water vapor interacts with the world in a variety of ways, all of which are the basis by which life exists.

Evaporation
- Water vapor in the air is mainly due to evaporation. About 90 percent of water in the air is evaporated from lakes, rivers, oceans and seas, while the other 10 percent is produced through plant transpiration. The amount of water vapor in the air that is returned to the Earth as precipitation is roughly the same as the amount of water evaporated.
Condensation
- After water vapor enters the air, it begins the process of condensation. Condensation occurs when water vapor enters cooler air, which then forms clouds. Even without clouds, water vapor in the air is constantly present. The volume of water estimated to be in the atmosphere at any time is roughly 3,100 cubic miles, which is about 0.001 of the total water volume of Earth.
Behavior
- Though the amount of water vapor traveling through the air is great, the atmosphere does not have a high ability to store it. Water in the air is constantly in motion and returns to the ground as precipitation relatively quickly. In this way, the evaporation to precipitation portion of the water cycle is like a highway, moving water around the world to areas it would not otherwise reach.
Precipitation
- Of the water vapor evaporated from the oceans, about 90 percent falls back into the oceans as precipitation. The remaining 10 percent is transported, then falls on land as precipitation. Precipitation can take the form of rain, sleet, hail or snow depending on the conditions in which it falls. This process, from evaporation to precipitation, takes about 10 days from beginning to end.

Nature