By Cammie Goodman

What makes planet Earth different from our solar systems other planets?Water

Earth is the only planet with bodies of liquid water on its surface. Without water, life on Earth would not be possible. Energy from the sun keeps water moving and

changing, but the amount of Earths water stays about the same.

How Water Cycles

The water cycle is the movement of water between Earth’s surface and atmosphere.

• Water moves from the oceans and land into the air and back again.

• Recall that a cycle is a set of events that happen over and over.

• It does not have a beginning or end. But you can think of the water cycle as having four main steps.

Step 1 The sun warms liquid water on

Earth’s surface in oceans and lakes.

The sun’s energy makes some of the liquid water change to a gas.

The change from a liquid to a gas is called evaporation. Recall that water in the form of a gas is called water vapor.

The water vapor rises into the air. It moves from Earth’s surface into the atmosphere.

Step 2 As water vapor rises, it

cools off. When it gets cool enough,

the water vapor changes back to liquid water.

This change from a gas to a liquid is called condensation.

The water vapor condenses into tiny droplets of liquid water.

These droplets form clouds.

Step 3 Droplets of liquid water in

clouds combine with other droplets and grow.

When they become too big and heavy, they fall into Earth’s surface as precipitation.

Precipitation is water that falls from the atmosphere.

It includes rain, snow, hail and sleet.

Liquid and frozen water fall from the atmosphere to Earth’s surface as precipitation.

Also, water vapor in the atmosphere condenses directly onto Earth’s surface to form liquid drops called dew.

Step 4 Some precipitation falls into the oceans. Some

falls on land. Some of this water sinks into the ground.

Some of it flows downhill over the ground. Water that flows over the ground is called runoff.

It flows into bodies of water, such as rivers, lakes, and oceans. There, evaporation keeps the water cycle going.

The Water Cycle Animation Video

The Water Cycle Video

BrainPop Video- The Water Cycle

Bill Nye the Science Guy - Water Cycle

Lesson Review

1.In the water cycle, what happens during evaporation?

a.Water vapor changes to liquid waterb.Water falls to the ground from cloudsc.Liquid water changes to water vapord.Water flows over the ground.

2. During condensation

a.Water vapor changes to liquid waterb.Liquid water changes to water vaporc.Water sinks into the groundd.Water falls to the ground from clouds

3. Where does precipitation begin to form?

a.In oceansb.In lakesc.Under the groundd.In clouds

4. The water cycle has

a.A beginning and an endb.No beginning and no endc.Only a beginningd.Only an end