Water Cycle

What Is Water Cycle?

Water cycle is also known as hydrologic cycle or hydrological cycle. It describes how water moves continuously on Earth.

Water loops through different stages – evaporation, condensation, precipitation and flow. It then goes back to the evaporation stage.

The whole cycle starts all over again and hence the name “water cycle”.

Water Cycle Learning Chart

For teachers and homeschoolers, here is a very helpful teaching aid — water cycle chart.

This 17″ x 22″ water cycle charts is a great visual learning resource in the classroom and homeschool.

The layout is simple and clear. The colorful illustration is easy to understand. It is printed on quality paper, perfect as a durable wall poster!

Stages Of The Water Cycle

Water covers 70% of the Earth’s surface and makes up approximately 60% of our bodies. This amazing natural resource is essential for life in both animals and plants.

Besides having many amazing properties, water is the only substance that appears on Earth naturally in all three physical states of matter — gas (water vapor), liquid (water), and solid (snow, ice). Most other substances only exist in one state in nature.

As water goes through the different stages of the water cycle, it changes from one form to anther by absorbing or releasing heat energy in the process.

Water cycle diagram

Evaporation

Evaporation over the ocean

Evaporation takes place wherever there is exposed water, e.g. on the surface of the ocean, rivers or lakes, when we sweat, when animals sweat and when plants transpire.

When the sun heats up exposed water, the water on the surface turns into vapor and goes into the air.

Evaporation can happen at any temperature, but warm water evaporates faster than cold water. If you boil the water, you can see steam rising from the surface. That is a fast, visible evaporation.

Even when you cannot see steam or vapor, evaporation can still be happening although at a much slower rate. You can try this Evaporation –> Distillation experiment to see how water can evaporate even at room temperature.

Condensation

Water condensation on a leaf

When water vapors in the air rise and reach the upper atmosphere, the cold temperature causes them to release heat and change back into liquid. These fine water droplets hang on dust particles in the air to form clouds.

In this Can You Make Rain experiment, condensation takes place on the bottle’s wall to form water droplets. This is a very neat experiment and also a water cycle all by itself.

Precipitation

Precipitation is rain

As water droplets collide and condense together in the upper atmosphere, they grow larger and heavier.

When the water droplets’ fall speed exceeds the cloud updraft speed, they fall out of the cloud as precipitation in the form of rain, freezing rain, sleet, snow or hail.

Flow

River flow

Through precipitation, water falls back onto the Earth’s surface.

Some water flows downward and ends up in the sea, lakes or rivers. Some soaks into the ground and becomes ground water, which feeds the plants or runs through the soil ending up in the ocean. Some is consumed by animals.

From there, the water cycle starts all over again.

water cycle in a bag using markers and blue water

Simple Water Cycle In A Bag Experiment

Prep Time: 15 minutes
Active Time: 40 minutes
Total Time: 55 minutes
Difficulty: Low

In this simple “water cycle in a bag” experiment, we will observe the different stages of the water cycle process up close.

Materials

  • a ziplock plastic bag (I used 2 Gallon bag)
  • color markers (e.g. Sharpie Permanent Markers or any non-erasable markers)
  • water
  • blue food coloring (optional)
  • packing tape

Tools

  • adult supervision

Instructions

  1. Draw the watercycle diagram.
    Water cycle drawn on a ziploc bag using makers
  2. Warm up the water until steam starts to rise but do not let it boil.
  3. Add blue food coloring into the water to represent ocean water.
  4. Pour the water into a ziplock bag and zip it up.
  5. Hang the bag upright on the window (or the door like I did) using packing tape.
  6. As the water evaporates, vapors rise and condense at the top of the bag. A white patch can be seen resembling clouds in the upper atmosphere.
  7. After a while, water droplets appear on the inside of the bag. As they become bigger, they will eventually slide downward. The sliding down resembles the flow stage that brings water back into the sea. 
    Drawn illustration of precipitation, surface flow and condensation in Water Cycle In A Bag Simple Science Experiment For Kids Condensation
  8. If the water is still warm or if the bag is left on the window facing sunlight, it will keep cycling through the four different stages of the water cycle.

Notes

Explore more about the water cycle by answering these questions.

  • Can you describe the relationship between the water cycle and living things?
  • How does snow fit into the water cycle process?
  • What causes soil erosion?
  • Have you seen the four stages of the water cycle appear in our daily lives?

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