The Water Cycle

What will you learn?

Wow! You have learnt the three states of matter, namely solid, liquid and gas. This book will now help you understand what the water cycle is and the processes that are involved in the water cycle. You will understand how these three states of matters are involved in the processes of water cycle that help us recycle the water on earth.

As you read each page, you may wish to click on "Teacher Lesley", "Teacher Cindy" and "Teacher Robert" for more learning points. Teacher Lesley will ask you a question about the topic. Teacher Cindy will give you a hint on the question and Teacher Robert will provide you with his thoughts and answer to the question.

On some pages, there is a video link which will illustrate to you visually what the content is about.

You can also click on the "play" button on the audio bar at the bottom of each page to listen to the content of this book.

Picture source:
http://israelity.com/wp-content//rain-blog.jpg

http://www.dillon3.k12.sc.us/RainCloud.gif

Content of this book

Page 1-3   : Introduction and goals
Page 4-5   : General information about water cycle
Page 6      : Evaporation
Page 7-8   : Condensation
Page 9      : Precipitation
Page 10     : Collection
Page 11     : Summary
Page 12-13: Revising what you have learnt
Page 14    : Further studies or extension

Picture source:

http://community.seas.columbia.edu/weatherstation/glo/images/diag_water_cycle.gif

Recall that matter naturally exists in 3 forms: Solid, liquid, and gas. Likewise, water exists not only in the liquid state, but also in the solid and gas state as ice and water vapor.

Picture source:

http://www.physics.utoronto.ca/~smorris/edl/icespikes/Ice_Spike3.jpg

http://www.battelle.org/environment/publications/envupdates/summer2004/gfx/water.jpg

http://cache.eb.com/eb/image?id=93820&rendTypeId=4

The earth has a limited amount of water. The water in your glass may have fallen from the sky as rain just last week, but the water itself has been around pretty much as long as the earth has! The dinosaurs that roamed the earth millions of years ago also drink the same water as we do now!

The water cycle explains how the water is recycled and used for so many years. The water cycle is a series of processes that changes water from one form to another form and back again while in the earth atmosphere.

Let us now learn each of these processes in more detail. These processes are evaporation, condensation, precipitation and collection.

Picture source:

http://photo2.si.edu/dino/cretac.gif

http://www.timeshares.marriott-vacations.com/common/marriott-timeshare/images/photo_big_beach_resorts.jpg

Evaporation is the process of changing liquid into gas. The sun heats up the water (liquid form) in rivers or lakes or the ocean and turns water into water vapor (gas form). The water vapor leaves the river, lake or ocean and goes into the earth atmosphere (air).

Here is a video of steam (water vapor) coming out from a spring.
http://www.youtube.com/watch?v=DMvdWSFJnmY




Picture source:

http://www.kidzone.ws/water/

http://www.smg.gov.mo/dm/learnmet/rain.jpg

You don't have to look at something as far away as a cloud to notice condensation, though*. You can see condensation right at your home! Pour a glass of cold water on a hot day and watch what happens. Water forms on the outside of the glass. That water didn't somehow leak through the glass! It actually came from the air. Water vapor in the warm air, turns back into liquid when it touches the cold glass**.

Here is a video of condensation taking place when a glass of cold water is left on a warm day.

http://www.youtube.com/watch?v=bymT5AcV-C4

Picture source:

http://www.acornadvisors.com/Kitchen%20Newsletters/2007-06-07_Ice_Cold/ISP_Water_Glass.jpg

* Content taken from http://ga.water.usgs.gov/edu/watercyclecondensation.html

** Content taken from http://www.kidzone.ws/water/

When the cloud becomes too heavy and can no longer hold all those water droplets to remain suspended in the air, they fall back to the earth as precipitation. Precipitation occurs in a variety of forms: Hail, rain, sleetsnow. or

Here is a video of how snowing looks like.
http://www.youtube.com/watch?v=XkVGqaehD5Y

Here is a video of how raining looks and sounds like.

http://www.youtube.com/watch?v=LtDoav0qVoE&feature=related

Picture source:

http://www.zianet.com/msaxton/TX/arcticblast07/index.html

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. This process is called collection. When water 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*.

Picture source:
http://www.azwater.gov/dwr/Content/Find_by_Program/Drought_and_Conservation/Teacher_Resources/images/EarthsWaterCycle.jpg

* Content taken from http://www.kidzone.ws/water/

In summary, water recycles itself through the water cycle. Water enters the earth atmosphere by a process known as evaporation, and then in condensation it forms clouds. Lastly, through precipitation, the water falls back down to earth where it is collected in lakes, rivers, ocean or land. This cycle then repeats itself over and over again and hence recycles the water.

If you would like to watch an animated video of the water cycle, please click here.

Picture source:
http://www.windows.ucar.edu/tour/link=/earth/Water/images/water_cycle_ucar_jpg_image.html

Now that you have learnt the water cycle and its processes, try the following questions.

Number the steps in the water cycle given that the first step is as shown:

Water is evaporated from the land, river, ocean, etc. __1__

a) The clouds give off precipitation in the form of rain, snow or hail. _____

b) Water vapor rises into the atmosphere where it condenses to form clouds _____

c) The water then goes back into the land, ocean to begin the cycle again _____

Idea source:
http://www.cdli.ca/CITE/water_cycle.pdf

Add the terms listed below to the diagram of the water cycle.

1) Collection 2) Precipitation 3) Evaporation 4) Condensation




Picture and idea source:
http://www.kidzone.ws/water/cactivity1.htm

Congratulations! You have learnt the key processes of the water cycle. However, there can be more learning for those who would like to pursue this topic in more details. Should you like to learn more on your own outside the curriculum for primary 3, you can find more information at this website.

http://www.mbgnet.net/fresh/cycle/index.htm

Picture source:
http://www.kidzone.ws/water/