What is a Watercycle?
Round and Round we go - The Water Cycle
Water is the only substance on earth that naturally exists in 3 states - solid (ice), liquid (water) and gas (water vapour). Water continuously cycles between each state forming the water cycle. Water from lakes and oceans evaporates to from water vapour, water vapour in the atmosphere forms clouds, clouds produce rain and snow. As a result, water is constantly recycled.
Facts:
There is the same amount of water on earth now, as there was 1 million years ago. In fact, the water we use now is the same water that the dinosaurs drank.
Experiment:
More than 97% of the water in the world is salty, but rain is not. The water cycle helps purify water as it evaporates, constantly recharging our freshwater. Make your own water cycle and see how it's done.
You'll need:
A large mixing bowl, water, salt, a drinking glass shorter than the height of the bowl, several clean marbles, plastic wrap, and a large elastic or masking tape
What to do:
- To create your 'ocean' put about 5cm (2 inches) of water in the bowl. Add about a tablespoon of salt and stir it around. Taste the mix, it should taste salty (if it doesn't, add more salt).
- Set the glass right side up in the bowl. If it floats at all, add a few marbles to weigh it down. This creates the 'land' part of the water cycle.
- Stretch the plastic wrap over the top of the bowl leaving a very little bit of slack. Put the elastic around the edges to hold it in place or tape it in place with the masking tape.
- Put a marble or two in the center of the plastic wrap, directly over the glass. You want the plastic to dip down slightly, but not touch the glass.
- Place your water cycle outside or in a window in direct sunlight. Leave it for several hours.
What Happened?
Just like in the real water cycle the sun causes some of the 'ocean' water to evaporate. When the water vapour hits the plastic it condenses into a fine mist on the plastic or 'clouds'. The droplets become bigger and bigger and eventually fall back down as 'rain'. If you taste the water that was collected in the cup (where the 'rain' fell over 'land') you will find that it is clean fresh water and not salty at all. When water evaporates, impurities such as salt and other contaminants get left behind.
Modified from
http://www.emints.org/ethemes/resources/S00000329.shtml