Get a glass of water and put it on the table
next to you. Take a good look at the water. Now -- can you guess how old
it is? The water in your glass may have fallen from the sky
as rain last week, but the water itself has been around as long
as the earth has!
When the first fish crawled out of the ocean onto the land, your glass of water was part of that ocean. When the Brontosaurus walked through lakes feeding on plants, your glass of water was part of those lakes.
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. Look at the photo.
Does water evaporate only from rivers, lakes and oceans? No, people sweat (perspire and plants transpire, that is, plants lose water out of their leaves). This process is called transpiration. The combination of *evaporation and *transpiration is called evapotranspiration. Look at the photo.
When water falls back to earth as precipitation, it may fall back in the oceans, lakes or rivers or it may end up on land. When it ends up on land, it will either soak into the earth and become part of the “ground water” that plants and animals use to drink or it may run over the soil and collect in the oceans, lakes or rivers where the cycle starts all over again.
Different types of *collection:
- *Surface run-off: the excess of rain flows over the land
- *Infiltration/Percolation (groundwater flow or groundwater recharge): process where water moves downward from surface water to groundwater.
1. Let's see if you have understood the water cycle. Click here
2. Complete the chart
|The Word Starts With this Letter||Hint||Answer|
|W||A substance that is very important to us. We need it to live, and it covers over two thirds of the surface of the Earth.||_____________________________|
|O||A large body of water on the surface of the earth.||_____________________________|
|E||A process in which liquid water turns into water vapor (a gas).||_____________________________|
|P||In transpiration, water from these objects evaporates into the atmosphere.||_____________________________|
|C||A fluffy-looking object in the sky that contains tiny water droplets or ice particles. It is formed when water vapor condenses.||_____________________________|
|R||This type of precipitation is water that falls from clouds in a liquid state.||_____________________________|
|S||This type of precipitation is water that falls from clouds in a fluffy, frozen state.||_____________________________|
|R||A large, flowing body of water that usually empties into a sea or ocean.||_____________________________|
|W||The process in which water circulates from the oceans to the clouds to the land to the rivers, and then accumulates back into the oceans.||_____________________________|
Check3. Complete the blanks in the paragraph below (the first letters are already filled in)
4. Watch this video that summarizes the water cycle very well. Use your earphones. Enjoy it!5. Now, an interactive game to summarize what you have learnt