Download - 08 Rainfall Ppt 08
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Climate & Weather
RAINFALL
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Is this a common sight in
Singapore?
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• Rainfall refers to the amount of rain that an area receives over a period of time
• Rainfall is necessary to provide us with our supply of water
• Long periods without rain will cause droughts to occur. – Example: Sahel Desert (Africa)
• Persistent or continuous heavy rain may lead to floods that can damage property and claim lives. – Example: Low lying areas of Bangladesh
Effects of Rainfall
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Land that is terribly dried up because of the lack of rain
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High amounts of rainfall results in flooding
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Measuring Rainfall
• Rainfall is measured using an instrument called a rain gauge
Funnel
Copper cylinder
Glass Bottle Outer Casing
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Measuring Rainfall
• It consists of a funnel that collects and channels rainwater into a container
• The water collected in the glass jar is then poured into a measuring cylinder to show the reading
• It is measured in millimetres (mm) or centimetres (cm)
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Measuring Rainfall
• It is represented in the form of vertical columns in climograph
• It should be placed in an open area where there are no obstructions to block the rain
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Formation of Rain
• When the Sun’s rays heats up the surface of the Earth, the air above it is warmed up.
• This causes the water from the land and oceans, seas and lakes to change into water vapour. This process is called evaporation
• Plants also give out water vapour into the air through a process called transpiration
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Formation of Rain• As the warm air rises, it begins to cool
• As soon as the air cools below a certain temperature, the water vapour that it is holding changes into very small water droplets
• This process is called condensation
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Formation of Rain
• These tiny water droplets will remain suspended in the air
• When more water droplets are gathered together, clouds are formed.
• When the droplets of water become too big and heavy to float in the air, they will fall to the ground as rain. This process is termed precipitation.
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Air cools
Clouds Condensation
Precipitation