The Water CycleThe Water Cyclep. D34-D37p. D34-D37

What happens during the What happens during the water cycle?water cycle?

•Water is recycled.Water is recycled.

•It changes from a liquid to It changes from a liquid to a gas.a gas.

•Then the gas changes Then the gas changes back to a liquid.back to a liquid.

What forces make the water What forces make the water cycle work?cycle work?

•SunSun

•WaterWater

•Air Air

•LandLand

EvaporationEvaporation

The sun warms the ocean, The sun warms the ocean, causing the water to enter causing the water to enter the air as water vapor.the air as water vapor.

This is the change from This is the change from liquid to gas.liquid to gas.

CondensationCondensation

•Water vapor high in the Water vapor high in the atmosphere cools and atmosphere cools and changes from a gas to a changes from a gas to a liquid. liquid.

•These water drops form These water drops form clouds.clouds.

PrecipitationPrecipitation

•Inside clouds, water drops hit Inside clouds, water drops hit each other and stick each other and stick together.together.

•Eventually they become too Eventually they become too big to stay in the air.big to stay in the air.

•They fall to earth as rain, They fall to earth as rain, sleet, snow, or hail.sleet, snow, or hail.

More About PrecipitationMore About Precipitation

•Some precipitation collects Some precipitation collects in lakes, rivers, and other in lakes, rivers, and other bodies of water.bodies of water.

•Some soaks into the ground.Some soaks into the ground.•Some falls back into the Some falls back into the

ocean.ocean.

Ocean WaterOcean Water

•Ocean water is a mixture Ocean water is a mixture of water and dissolved of water and dissolved solids, mostly salts.solids, mostly salts.

•Sodium chloride is the Sodium chloride is the most common ocean salt. most common ocean salt. You know it as “table salt”.You know it as “table salt”.

Why is ocean water salty?Why is ocean water salty?

•Most of the salt comes from Most of the salt comes from land.land.

•Water flowing over land Water flowing over land breaks away rocks.breaks away rocks.

•Over time, salts from these Over time, salts from these broken rocks enter the broken rocks enter the oceans.oceans.

Salt Water FactsSalt Water Facts

• Ocean water is a bit saltier near the Ocean water is a bit saltier near the equator, because it is hotter and equator, because it is hotter and evaporation occurs faster. (salt is evaporation occurs faster. (salt is left behind)left behind)

• Ocean water is less salty near the Ocean water is less salty near the poles, because it is colder. There is poles, because it is colder. There is less evaporation here. (warmth is less evaporation here. (warmth is needed for evaporation)needed for evaporation)

Final ThoughtFinal Thought

•Water vapor entering the Water vapor entering the air from the ocean has lost air from the ocean has lost its saltiness. its saltiness.

•This is why precipitation This is why precipitation falls as fresh water instead falls as fresh water instead of salty water.of salty water.