THE HYDROSPHERE. Do you konw……..? Where can we find water in our planet? Where can we find water in our planet? How is sea water different to water in.

THETHE HYDROSPHEREHYDROSPHERE

Do you konw……..?Do you konw……..?

• Where can we find water in our Where can we find water in our planet?planet?

• How is sea water different to water in How is sea water different to water in rivers?rivers?

• What is the water cycle?What is the water cycle?

• Why is important not to waste water?Why is important not to waste water?

• Some easy ways to save water?Some easy ways to save water?

WHERE IS WATER ON THE WHERE IS WATER ON THE EARTH?EARTH?

WHERE IS THERE WATER ON WHERE IS THERE WATER ON EARTH?EARTH?

• 97% of water on Earth is salt water. It is 97% of water on Earth is salt water. It is found in the oceans.found in the oceans.

• 3% of water on Earth is fresh water. It is 3% of water on Earth is fresh water. It is found in:found in:– Ice and snow from glaciars.Ice and snow from glaciars.– Below the surface: groundwater.Below the surface: groundwater.– In the atmosphere.In the atmosphere.– On the surface.On the surface.– In living beings.In living beings.

PROPERTIES OF WATERPROPERTIES OF WATER

• The water molecule is made up of three atoms: HThe water molecule is made up of three atoms: H22OO

• Water:Water:– Has no colour, no taste and no smell.Has no colour, no taste and no smell.– Is a poweful solvent.Is a poweful solvent.– Absorbs heat: so, water moderates the Earth’s climate by Absorbs heat: so, water moderates the Earth’s climate by

absorbing heat in summer and emitting heat in winter.absorbing heat in summer and emitting heat in winter.

SEA WATERSEA WATER

• Sea water is salty.Sea water is salty.

• It contains dissolved gasses: these gasses It contains dissolved gasses: these gasses are dissolved in the water by two process:are dissolved in the water by two process:

– The movement of the waves.The movement of the waves.– The aquatic beings.The aquatic beings.

• The temperature varies with depth:The temperature varies with depth:

It is highest at the surface.

It is lower in the deepest zones.

• MOVEMENTS PRODUCED IN THE MOVEMENTS PRODUCED IN THE OCEANS:OCEANS:

– WavesWaves: occur on the surface, and they are : occur on the surface, and they are caused by the wind. Waves mix water with the caused by the wind. Waves mix water with the air above the surface, dissolving a lot of air above the surface, dissolving a lot of oxygen.oxygen.

– CurrentsCurrents: are masses of water which : are masses of water which move like rivers through the sea. They move like rivers through the sea. They are produced by wind, and differences in are produced by wind, and differences in salinity.salinity.

– TidesTides: are the periodic rise and fall of : are the periodic rise and fall of the sea level. They are caused by the the sea level. They are caused by the gravitational attraction of the Moon and gravitational attraction of the Moon and the Sun.the Sun.

FRESH WATERFRESH WATER

• Fresh water is found on the continents.Fresh water is found on the continents.• It contains much less salt than sea water.It contains much less salt than sea water.• It is found in different forms:It is found in different forms:

– Streams: are water courses fed by rain.Streams: are water courses fed by rain.– Glaciers: are formed from the accumulation of snow on Glaciers: are formed from the accumulation of snow on

mountain tops.mountain tops.– Rivers: are permanent water courses. Rivers: are permanent water courses. – Lakes: are masses of water contained on depressed Lakes: are masses of water contained on depressed

areas.areas.– Groundwater: is water beneath the ground surface.Groundwater: is water beneath the ground surface.– Wetlands: are areas where the ground is inundated all Wetlands: are areas where the ground is inundated all

year round.year round.

THE WATER CYCLETHE WATER CYCLE

• Is the movement of water around, Is the movement of water around, over and through the Earth. It consist over and through the Earth. It consist on these processes:on these processes:

– Evaporation.Evaporation.– Evapotranspiration.Evapotranspiration.– Condensation.Condensation.– Precipitation.Precipitation.– Surface Runoff.Surface Runoff.

• EvaporationEvaporation: liquid water changes to gas. : liquid water changes to gas. Water passes from the hydrosphere to the Water passes from the hydrosphere to the atmosphere.atmosphere.

• EvapotranspirationEvapotranspiration: water evaporates : water evaporates from the leaves of plants.from the leaves of plants.

• CondensationCondensation: Water vapour changes to : Water vapour changes to liquid, forming clouds.liquid, forming clouds.

• PrecipitationPrecipitation: water in the clouds falls to : water in the clouds falls to the ground.the ground.

– Surface RunoffSurface Runoff: surface water moves : surface water moves across the land, forming rivers and across the land, forming rivers and streams.streams.

– InfiltrationInfiltration: surface water filters into : surface water filters into the ground, using the pores in the rocks. the ground, using the pores in the rocks.