The Water Cycle

• The continual movement of water throughout our planet.

• A cycle is something that repeats.

The Water Cycle

• The water cycle is powered by the Sun.

• When liquid water is heated it turns into a gas called water vapor.

• When water vapor cools it turns back into liquid water.

Evaporation• Heat energy from the sun causes

water in puddles, streams, rivers, seas or lakes to change from a liquid to water vapor.

• This is called evaporation.

• Liquid heat water vapor

Condensation• Air carries water vapor high into the sky,

where it will cool. As heat leaves, water vapor turns back into liquid water droplets.

• This is condensation.

• Water Vapor heat liquid water

Cloud Formation• As water vapor cools and becomes liquid, dust is

trapped with it in the atmosphere.

• Clouds form when many tiny water droplets and dust particles collect together high in the atmosphere.

• Clouds form during the condensation phase of the water cycle.

• Water Droplets Dust Particles Clouds

Where else can you find examples of condensation?

• Hint - Where does the water come from on the outside of this glass?

• Why does this occur?

Precipitation

• When clouds become heavy with many condensed water droplets and dust particles, the drops fall to Earth as precipitation.

• Depending on the air temperature, it may fall as rain, snow, sleet or hail.

Transpiration• Transpiration is the process where

plants lose water from their leaves.

• It is similar to evaporation.

• Heat energy from the sun causes plants to “sweat” much like people.

• Transpiration causes water vapor to go into the air.

Accumulation

• After water falls to Earth, it runs across the land.

• Accumulation is the process in which water from surface runoff collects or pools back in large bodies of water.

• Oceans hold most of the water.

• Rivers, streams, lakes and groundwater also hold water.

EvaporationThe vapor rises

CondensationThe Clouds form

PrecipitationThe rain falls

Transpiration

The movement through plants

Water Cycle

Where is our water?• Scientists believe the water on Earth Scientists believe the water on Earth

today is the same water that has today is the same water that has been here since Earth was created.been here since Earth was created.

• Oceans and seas cover about Oceans and seas cover about

70-75% of Earth’s surface.70-75% of Earth’s surface.

• Earth is sometimes called the water Earth is sometimes called the water planet.planet.

• Oceans and seas are very deep and Oceans and seas are very deep and hold about 97% of all the water on hold about 97% of all the water on Earth.Earth.

• All of the water in the oceans and All of the water in the oceans and seas is salt water that people cannot seas is salt water that people cannot drink.drink.

Earth’s fresh water

• If 97% of Earth’s water is salt water in the oceans, then only 3% is non-salt water, or fresh water.

• Fresh water is what people, animals and plants need to survive.

• Of this small amount of fresh water, most is frozen in glaciers and polar ice caps.

• 2% of Earth’s water is frozen fresh water.

The rest of the fresh water

• Only 1% of Earth’s water is liquid fresh water. • It is found in groundwater, lakes, ponds, rivers,

the atmosphere and in people, plants and animals• Fresh drinking water is a limited resource.

Water – Just the Facts

• 97% of all Earth’s water is in the oceans and seas

• 3 % of all Earth’s water is fresh water

• 2% of all Earth’s water is fresh, frozen water in glaciers and ice caps

• 1% of all Earth’s water is fresh, liquid water in groundwater, lakes, rivers, streams, the atmosphere, people, plants, and animals

Do we have enough water?

Constructed Response:

• Describe one pathway water can take in the atmosphere. Begin with water that falls to Earth as rain and end with water in the clouds in the atmosphere.

• Write in complete sentences and use the back of the page if needed.

• Use these vocabulary words: evaporation, condensation and precipitation.