Water Cycle Demonstration
Materials:
- 1 round plastic Pyrex dish
- 1 large plastic bottle cap
- Saran wrap/ cling wrap
- Water
Instructions:
1. Find a sunny spot in your home. The garden, patio, or a windowsill works well.
2. Put the plastic bottle cap at the center of the dish.
3. Pour water around the bottle cap, making sure that no water spills into the cap itself. The cap should not float in the water, so don't pour too much. If the cap is floating even with just a little water, hold it down by placing a rock in the middle.
4. Cover the dish with the cling wrap, making sure it is sealed tightly over the dish and no air can come in or out of the dish.
5. Leave your dish out in the sun and check on it every few hours.
6. Once you notice that there is water on the cling wrap, you are just a few hours away from the final result!
7. Go back to your water cycle when the day has cooled, usually after the sun goes down. If there is no more water on the cling wrap, peel it off and look into the cap. What do you see?
When the sun heated the water in the dish, it evaporated. Water vapor couldn't escape into the air because the cling wrap was wrapped tightly around the dish, so it evaporated and stayed within the area covered by the cling wrap. When condensation occurred, the water droplets clung to the cling wrap. At the stage of precipitation the water falls or drips down back onto the dish. Ideally, some water will fall into your bottle cap, which originally had no water in it. This shows that the water cycle did happen within your closed system.
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