UNIT 6
SURFACE WATER
RIVER
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A river is a flow of water that is bigger and deeper than a
stream.
STREAM
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A stream is a very small river that originates in mountains.
LAKE
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A lake is a large area of water surrounded by land.
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Most lakes on the Earth contain fresh water.
GLACIER
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A glacier is an area of moving ice.
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Glaciers form in high altitudes.
OCEAN
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An ocean is a huge area of salt water.
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There is
only one ocean, called the World
Ocean.
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The World Ocean consists of
five interconnected parts:
·
The Pacific ocean.
·
The Atlantic ocean.
·
The Indian ocean.
·
The Artic ocean.
·
The Southern ocean.
GROUNDWATER
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Groundwater is water found below the surface of the Earth.
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Most groundwater comes from rainfall.
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A spring is the place where the ground water meets
the Earth´s surface.
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We find groundwater in layers of sandstone called aquifers.
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Below an aquifer there is a layer of clay that traps the
water.
-
To get
groundwater out of aquifers we use pipes and wells.
THE THREE STATES OF WATER
We can find water
in nature in three different states:
LIQUID WATER
-
Rain, water in rivers, lakes and oceans are examples of water in a
liquid state.
GASEOUS WATER
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Clouds, steam, fog and mist are examples of water in a gaseous state.
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It is quite difficult to see water in this state.
SOLID WATER
-
Ice, snow and hail are examples of water in a solid state.
CHANGES IN THE STATES OF WATER
CONDENSATION:
GAS TO LIQUID
-
Condensation is the change from
the gaseous state to the liquid state.
EVAPORATION: LIQUID TO GAS
-
Evaporation is the change from
the liquid state to the gaseous state.
FREEZING: LIQUID TO SOLID
-
Freezing is the change from
the liquid state to the solid state.
MELTING:
SOLID TO LIQUID
-
Melting is the change from
the solid state to the liquid state.
SUBLIMATION:
SOLID TO GAS
-
Sublimation is the change from
the solid state to the gaseous state.
DEPOSITION:
GAS TO SOLID
-
Deposition is the change from
the gaseous state to the solid state.
THE WATER CYCLE
EVAPORATION
-
The Sun heats water in rivers, lakes and oceans and turns
it into vapour.
CONDENSATION
-
Vapour from the air cools and turns into clouds.
PRECIPITATION
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When a big amount of water condenses, it falls as
precipitation: rain, snow or hail.
COLLECTION
-
When water falls, it forms rivers, lakes, oceans…
USES OF WATER
RECREATIONAL USE
-
We use water for a lot of recreational activities, for example: fishing,
swimming, sailing…
HYDROPOWER
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Water is a renewable source of energy
-
We use the hydropower to produce electricity.
AGRICULTURAL USE
-
We use approximately 70% of the water in the world for irrigation.
AT HOME
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We use water for drinking, showering, cooking and washing.
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A person in Spain uses approximately 50 litres of water per day.
