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Geographical Eye Special: Planet Earth
Programme 3: Precipitation
Activity 1
(a) Number the diagrams below in order from 1 to 8 to show the process that leads to precipitation.
Sometimes the droplets
collide and grow.
Water vapour rises in the
warm air.
Water evaporates as it is
Once the air is saturated,
heated. It changes from a
if it cools further then the
liquid into a gas (water vapour). water vapour condenses and
a cloud is formed.
The sun’s energy warms up
the earth’s surface.
As warm air rises, it cools,
and the air become
saturated.
Water condenses onto dust
and smoke particles in the
atmosphere, forming tiny
droplets.These form clouds.
When cloud droplets
become too heavy to
remain floating, they fall to earth
as rain, snow, hail or sleet.
© Channel Four Learning
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Net NotesPLUS
Geographical Eye Special: Planet Earth
Programme 3: Precipitation
Activity 1
(b) Convectional Rainfall
Convectional rainfall is particularly common in equatorial regions, such as Brazil’s rainforests, where it is
very hot all year round.
Number the diagrams below in order from 1 to 6 to show the process that leads to convectional rainfall.
1) As the air rises, it cools to
the dew point, forming
cumulus clouds.
2) This leads to very heavy
convectional rainfall.
3) The morning sun heats the
ground and the air above it.
4) The surface water
evaporates quickly.
5) Hot air containing a
lot of water vapour
expands and rises.
6) More and more rising and
cooling water vapour forms
cumulonimbus clouds.
(c) Relief rainfall
Rain also falls as a result of the relief (shape) of the land.
Annotate the diagram below to show the process that leads to relief rainfall.
Use the following vocabulary in your annotations:
• temperature
• water vapour
• condensation
• clouds
• moist air
© Channel Four Learning
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Net NotesPLUS
Geographical Eye Special: Planet Earth
Programme 3: Precipitation
Activity 1
(d) Frontal Rainfall
Frontal rainfall occurs when warm, moist air from the tropics meets cold dry air from the polar regions.
Number the diagrams below in order from 1 to 4 to show the process that leads to frontal rainfall.
The warm air cools as it rises, and
widespread clouds are formed as
water vapour condenses.
The rain begins well ahead of the
advancing front, and continues as
the front advances.
The warmer air is lighter than the
colder air, and is forced to rise over it.
The front is where a mass of warm
moist air meets a mass of cold dry air.
© Channel Four Learning
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Net NotesPLUS
Geographical Eye Special: Planet Earth
Programme 3: Precipitation
Activity 1
(e) Predicting the Weather
Satellites orbiting the Earth help us to predict the weather.
Add captions to the images stating how weather forecasting is important to different industries.
© Channel Four Learning
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Net NotesPLUS
Geographical Eye Special: Planet Earth
Programme 3: Precipitation
Activity 1
(f) Prevailing Winds
The weather is largely determined by the Earth’s major winds. Air flows from areas of high pressure
to areas of low pressure. The winds are caused by the heating of the sun.
(i) Label the parts of the diagram below with the numbers of the sentences describing them.
1
Air moves from the midlatitudes to the poles, where
it cools and sinks in a region
of high pressure. This
causes a flow of very cold air
away from the poles. This is
the Polar Cell.
2
The Earth’s surface is heated
most around the equator. The
hot moist air rises, setting up a
convection cell and leaving an
area of low pressure. As the
air rises, it cools, spreads out
and descends again near the
subtropics. Some of this air
streams back to the equator as
the ‘trade winds’. This is the
Hadley Cell.
© Channel Four Learning
3
Some air moves from the
subtropics towards the
poles. As the warm air
meets cold air from the
polar regions, it rises over
it in a low-pressure region.
Some of this air flows back
towards the tropics. This is
the Ferrel Cell.
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Net NotesPLUS
Geographical Eye Special: Planet Earth
Programme 3: Precipitation
Activity 1
(ii) The winds on the Earth’s surface tend to blow into areas of low pressure and out of areas of
high pressure.
On the diagram below, label two areas of low pressure and two areas of high pressure.
(iii) The winds don’t blow in a simple north-south direction because of the Earth’s rotation.
Label the trade winds on the diagram below.
The prevailing winds in Britain blow from a ...................... direction.
© Channel Four Learning
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Net NotesPLUS
Geographical Eye Special: Planet Earth
Programme 3: Precipitation
Activity 1
(g) Anticyclones
Anticyclones are associated with areas of high pressure, and settled weather.
(i) Draw annotated diagrams for statements 2, 3 and 4 below to show how an anticyclone is formed.
(ii) Use the images to help you complete statements 5 and 6.
1. Satellite image showing
high-pressure, anticyclonic
conditions over Britain.
2. Anticyclones are formed
when cold air descends and
warms up.
3. As the air descends, it gets
warmer, causing the moisture
to evaporate, so clouds cannot
form.
4. So anticyclones are
associated with cloud-free
conditions.
5. In autumn and winter,
anticyclonic conditions lead to
6. In summer, anticyclonic
conditions lead to
© Channel Four Learning
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Net NotesPLUS
Geographical Eye Special: Planet Earth
Programme 3: Precipitation
Activity 1
(h) Cyclones: Tropical Storms
Some of the world’s most devastating weather occurs in Bangladesh as a result of extremely lowpressure cyclones.
Number the diagrams below in order from 1 to 6 to show how tropical cyclones are formed.
The winds rotate in a vortex that can be
1000 kilometres across.
As it rises, the air cools rapidly, causing water
vapour to condense and fall as rain.
Tropical storms or cyclones form
over seas warmer than 27ºC.
Very moist, hot air rises rapidly from the
surface of the sea.
The centre of the vortex is quite calm. This
is called the eye of the storm. It can be
observed using satellite images.
The process of condensation produces huge
amounts of heat, resulting in violent winds.
Driven by the spin of the Earth, these winds
rotate, rising rapidly around a centre of
extremely low pressure.
(i) Produce a glossary for all the vocabulary in bold print above.
© Channel Four Learning
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