evaporation Evaporation!


What is evaporation?
Evaporation from the oceans is the primary mechanism supporting the surface-to-atmosphere portion of the water cycle. Evaporation is when the sun heats up water in rivers or lakes or the ocean and turns it into vapor or steam. The water vapor or steam leaves the river, lake or ocean and goes into the air.


The rate of evaporation depends upon:

Wind speed: the higher the wind speed, the more evaporation

Temperature: the higher the temperature, the more evaporation

 Humidity: the lower the humidity, the more evaporation

Examples in the real world:

1. Wet streets after a rain eventually dry out when the sun shines.

2. Wet clothes are put into a dryer and come out dry.



The amount of water evaporating is about the same as the amount of water delivered to the Earth as precipitation. Evaporation is more prevalent over the oceans than precipitation, while over the land, precipitation routinely exceeds evaporation. Only about 10 percent of the water evaporated from the oceans is transported over land and falls as precipitation. Once evaporated, a water molecule spends about 10 days in the air. The process of evaporation is so great that without precipitation runoff, and ground-water discharge from aquifers, oceans would become nearly empty.

If you ever find yourself stranded on an island in need of salt, just get a bowl, add some seawater, and wait for the sun to evaporate the water, leaving the salt. Much of the world's table salt is produced within evaporation ponds, a technique used by people for thousands of years.


[msti 260] [the water cycle] [condensation] [precipitation] [runoff] [percolation] [glossary]