The Water Cycle
By Sarah Lane
May 27, 2004, 11:33


Topic: The Water Cycle

ClassBrain Visitor:

Hi. I need to know about all the processes involved in the water cycle. Like, I know about transpiration, evaporation, and condensation but I don't really know how and when they work during the water cycle. I also need to know all about osmosis and what role it plays in the water cycle.

ClassBrain Response:

With the help of a few sources, we will try to answer your question as clearly as possible.

The Water Cycle

Water moves from the sky to Earth and back to the sky again. This is called the Water Cycle or Hydrologic pattern. Water falls to Earth in the form of rain, sleet, snow, or hail. Some of that water soaks into the ground and is stored as groundwater. The rest flows into streams, rivers, lakes and oceans. The sun then warms that water and changes some of it into water vapor. This is called evaporation. Plants give off water vapor in a process called transpiration. The heated water vapor rises into the sky and forms clouds. When the vapor in the clouds condenses and becomes heavy, it falls back to Earth as rain, sleet, snow or hail. The water cycle then starts all over again.


As far as osmosis and the role it plays in the water cycle, it works throughout plants to help them grow. During the transpiration cycle that we talked about earlier, plants move water from the soil through roots and stems to leaves and into the outside air. Water enters the roots in a process called osmosis. Osmosis is the push that water gives as it tries to make plant roots as full of water as the damp soil around them. When the root is full of water, osmosis works to carry water through cell membranes into the xylem (think of xylem as pipes) that carry the water from roots to stems to leaves. Osmosis through these cells is called root pressure.

Hopefully that explains things for you. If you need more information, check out the Environmental Protection Agency. They have some really cool materials on this subject.

Learn more about the water cycle with the help of Google

© Copyright 2003 by