Water and The Water and The Water CycleWater Cycle

Water on EarthWater on EarthWater is a dominant feature on Earth’s surface and is

essential for life.

• Salt water and freshwater make up Earth’s water supply.

• In the water cycle, water circulates from Earth’s surface to the atmosphere and back again.

• Water plays an important role in people’s lives.

Salt water and freshwater Salt water and freshwater make up Earth’s water make up Earth’s water supply.supply.

About About 9797 percent of the Earth’s water percent of the Earth’s water

Unsafe to Unsafe to drinkdrink because of high levels of salt because of high levels of salt

In general, found in Earth’s oceans, which cover In general, found in Earth’s oceans, which cover some some 7171 percent of the planet’s surface percent of the planet’s surface

Also found in some of Earth’s Also found in some of Earth’s lakeslakes

Earth’s Water Water covers some Water covers some two-thirdstwo-thirds of the planet. of the planet.

Salt Water

Water without saltWater without salt

Makes up only Makes up only 33 percent of our water supply percent of our water supplyFreshwater

FreshwaterFreshwater Much of Earth’s freshwater is locked in Much of Earth’s freshwater is locked in glaciersglaciers, large areas of , large areas of

slow moving ice, and in the ice of the Arctic and Antarctic regions.slow moving ice, and in the ice of the Arctic and Antarctic regions.

Surface waterSurface water is water that is found in Earth’s streams, rivers, and is water that is found in Earth’s streams, rivers, and lakes.lakes.

Less than one percent of Earth’s water supplyLess than one percent of Earth’s water supply

Streams, rivers, and lakes are common sources.Streams, rivers, and lakes are common sources.

PrecipitationPrecipitation is water that falls to Earth’s surface as rain, snow, is water that falls to Earth’s surface as rain, snow, sleet, or hail.sleet, or hail.

Most available freshwater is Most available freshwater is groundwatergroundwater, water found below , water found below Earth’s surface.Earth’s surface.

Some naturally bubbles from the ground to the surface as a Some naturally bubbles from the ground to the surface as a spring.spring.

Most obtained by digging wells Most obtained by digging wells

The Water CycleThe Water Cycle Water is the only substance on Earth that occurs naturally as a solid, a Water is the only substance on Earth that occurs naturally as a solid, a

liquid, and a gas, or liquid, and a gas, or water vaporwater vapor..

The The water cyclewater cycle is the movement of water from Earth’s surface to the is the movement of water from Earth’s surface to the atmosphere and back ; it is driven by the sun’s atmosphere and back ; it is driven by the sun’s energyenergy..

EvaporationEvaporation—water turns from liquid to gas.—water turns from liquid to gas.

CondensationCondensation —the rising gas cools and condenses, or —the rising gas cools and condenses, or changes from a vapor into tiny liquid droplets, to form changes from a vapor into tiny liquid droplets, to form clouds.clouds.

PrecipitationPrecipitation —if the droplets in clouds become heavy —if the droplets in clouds become heavy enough, they fall back to Earth as rain, snow, sleet, or enough, they fall back to Earth as rain, snow, sleet, or hail.hail.

RunoffRunoff —excess water that isn’t absorbed as —excess water that isn’t absorbed as groundwater flows over land and collects in streams, groundwater flows over land and collects in streams, rivers, and oceans.rivers, and oceans.

Water plays an important Water plays an important role in role in people’s lives.people’s lives.

Water ProblemsWater Problems Lack of available Lack of available

freshwater, which can be freshwater, which can be caused by droughts or caused by droughts or overuseoveruse

Contaminated, or polluted, Contaminated, or polluted, water can harm humans, water can harm humans, plants, and animals.plants, and animals.

Flooding can damage Flooding can damage property and threaten lives.property and threaten lives.

Water BenefitsWater Benefits

Provides us with food to eatProvides us with food to eat

Important source of energyImportant source of energy

Provides us with recreation, Provides us with recreation, including swimming, including swimming, fishing, surfing, and sailingfishing, surfing, and sailing