Download - The Population Policy of South Africa

LEARNER GUIDE
SOCIAL SCIENCE
africa's weather and climate
KEY CONCEPTS
Oblique sunrays: When the sun's rays are less direct as they strike the earth at an angle and
this results in cooler temperatures.
Inter-tropical convergence zone (ITCZ): An area near the equator where the
South Easterlies (primary winds), meet the North Westerlies (primary winds).
Convectional rain: When the earth is heated it gives off the heat which it has absorbed.
The air resting on the earth is heated by the heat which is radiated by the earth and it expands.
This air rises and cools as it does so. Condensation takes place and eventually it rains.
Relief/ orographic rain: Air blows from the sea towards the land and is
forced to rise by the mountains. As the air rises, it is cooled and condensation takes place.
Rain falls on the windward side of the mountain - the side of the mountain which faces the sea.
Leeward side of the mountain: A mountain range which runs parallel to the coast, has two
sides. The side which faces the interior is the leeward side whereas the side which faces the sea
is the windward side.
Temperature range: The difference between the coldest and hottest temperatures. The range
would be 14° if the hottest temperature is 24°and the coldest is 10°. Temperature range can be
determined for a day, a week, a month, a season, a year, etc.
Advection fog: When cold air meets warm air near a coastline and there is no
mountain to lift the air, condensation will take place at sea level and tiny water droplets are
formed.
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• www.dsd.gov.za
• www.population.gov.za
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CHIEF DIRECTORATE POPULATION AND DEVELOPMENT
www.population.co.za
Private Bag X901, Pretoria, 0001, SOUTH AFRICA
COPYRIGHT© 2014, Department of Social Development, Pretoria, South Africa
For further information:
Chief Directorate Population and Development
Department of Social Development
Private Bag X901, Pretoria, 0001
SOUTH AFRICA
www.population.co.za
Tel: 012 312 7769/ 7410
Fax: 012 312 7710/ 312 7932
Email: [email protected], [email protected],[email protected]
This publication is intended to support learning about population and development in the school curriculum and may be
copied/downloaded and distributed as required. Permission should be obtained from the copyright holder for any
changes to the format or content of this publication. Distribution for remuneration is not permitted.
COPYRIGHT© 2014, Department of Social Development, Pretoria, South Africa
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Department of Social Development
Population Support material
SOCIAL SCIENCE
africa;s weather and climate
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Africa's main climate regions
Africa's weather, specifically its temperature and rainfall, influences the type of climate found in
each area. Refer to topic 4 for details on weather.
Tropical Desert (Sahara Desert).
Temperatures: Can be very high
(33°C) in summer.
In winter the days are warm (as
high as 20°C) but the nights are
very cold (about 2°C).
Equatorial rainforest (Congo Basin).
Temperatures: High all
year ranging
between 24°C and 32°C.
Rainfall: High - about
2000 mm per year.
Tropical continent (ZAMBIA)
Temperatures: Summer temperatures
of about 26°C. Winter temperatures
of about 10°C. Rainfall: About 700mm
in the summer months.
Semi-desert (Northern Karoo).
Tropical Maritime (Mozambique).
Temperatures: Hot summer temperatures
of about 28°C. Warm winter temperatures
of about 18°C.
Rainfall:High rainfall mostly in the
summer months - about 1500 mm.
Temperatures: Can be very low
(-2°C) in winter and very high
(32°C) in summer.
Humid Sub-tropical (KZN).
Mediterranean (SW Cape).
Temperatures: Winter about
10°C. Summer about 26°C.
Rainfall: 650 mm in the winter.
africa's weather and climate
Department of Social Development
Temperatures: Warm summer
temperatures of about 27°C.
Moderately warm temperatures
in winter of about 16°C.
Rainfall: Mostly in summer about 1000 mm.
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Population Support material
SOCIAL SCIENCE
africa;s weather and climate
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Factors that influence the climate of Africa
Latitude:
• Places that are closer to the equator
Average annual
temperature for Africa.
are much hotter than places further north
and south. This is because the sun's rays
are more direct at the equator and more
oblique further from the equator.
• The primary winds converge around the
equator in an area which is called the
Inter-tropical Convergence Zone. Over
the equator, the air is heated, it expands,
rises, cools and then condenses. This
results in heavy downpours of
convectional rainfall. These heavy
downpours of rain ultimately result in a
low population density.
Atlas of the Biosphere,
Centre for Sustainability and the Global Environment.
• Air which diverges over the equator will subside and warm up over the tropical latitudes. This is
the cause of the low rainfall and desert conditions in the tropical latitudes, eg. areas like the Sahara
Desert have low population densities.
• Cape Town, in the Western Cape, which has a latitude of 34°S, receives cyclonic rain (with its cold
fronts) in winter, as it is located in the latitudinal path (40° - 30°), of the westerly winds.
Altitude:
• Temperatures drop as height increases. The air is thinner higher up with less water vapour and
carbon dioxide, and it cannot absorb the heat that is radiated by the earth. Mountainous places
in Africa are therefore cooler as they have high altitudes. Mt Kilimanjaro in Tanzania, has a snow
cover in spite of the fact that it is 2°South of the equator where it should be hot!
• Mountains near the sea can also influence rainfall as air blows from the sea and is lifted by the
mountains, cools, condenses and falls as relief rain.
africa's weather and climate
Department of Social Development
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Population Support material
SOCIAL SCIENCE
africa;s weather and climate
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Distance from the sea:
• As the water of the ocean takes longer to heat up and retains heat for a longer period of time
than the land, the coastal places are cooled in summer and warmed in winter by the moderating influence of the sea.
• Temperatures along the coast are therefore moderated and this small temperature range between
summer and winter allows places alongside the sea, to have a 'maritime climate'.
• As Africa is a large continent, the vast interior experiences a large temperature range which gives inland
areas a 'continental climate'.
• The interior parts of Africa often lie in the lee of coastal mountains which means they are in a rain
shadow and experience drier conditions than coastal areas.
Ocean Currents:
• Warm ocean currents tend to raise the temperatures
and the rainfall of the countries they flow past. Evaporation off warm seas allows for relief rainfall, eg. warm
Mozambique Current raises temperatures of cities along
South Africa’s east coast (Durban).
• Cold currents lower the temperatures and rainfall of
the places past which they flow. These currents are
found on the west coasts of countries, eg. the Benguela
Current which flows along the west coast of South
Africa.
Source: "http://www.seos-project.eu/modules/oceancurrents/oceancurrents-c04-p05.html" \h www.seos-project.eu
As there is less evaporation and less condensation, desert conditions are common along the western
coast, eg. Namib Desert.
• Advection fog is created by the meeting of warm and cold air along coastlines. This type of fog is
formed off the west coast of South Africa, when the warm air from the desert meets the cold air above
the cold Benguela Current.
africa's weather and climate
Department of Social Development
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Population Support material
SOCIAL SCIENCE
africa;s weather and climate
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Climate extremes result in areas of low population densities
DESERT
africa's weather and climate
Department of Social Development
EQUATORIAL FOREST
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Population Support material
SOCIAL SCIENCE
africa;s weather and climate
DESERT
True Deserts: Sahara and Namib
Semi-Deserts: Kalahari and Nubian
Bordering desert areas: In Africa the
southern part of the Sahara Desert which
frequently suffers from droughts is called
the Sahel. This area includes part of the
following countries: Somalia, Ethiopia,
Sudan, Chad, Niger, Mali, Burkino Faso
and Mauritania.
In South Africa the bordering desert areas
are also referred to as semi-desert Karoo
areas. These are found in parts of the
Northern Cape, the Western section of
North West Province, the western section
of the Free State and the Little, Great and
Northern Karoo of the Western Cape.
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EQUATORIAL FOREST
Equatorial Rainforests: These are found
in parts of Nigeria, Ghana, Cameroon,
Central African Republic, Equatorial
Guinea, Gabon, Congo, Democratic
Republic of Congo, Rwanda and Uganda.
General climate and vegetation in these areas
• High temperatures in summer and often
very cold temperatures at night.
• Less than 100 mm of rain
• 20 km/h winds can result in dust storms.
• Sand dunes, erosional hollows with oases
and palm trees.
• Stone covered plains with succulents like
cacti and the occasional steep-sided
ravine.
africa's weather and climate
Department of Social Development
Hot humid conditions with temperatures
reaching 32°C.
• Heavy convectional rainfall of about 2000
mm, all year round.
• Thunder and lightning.
• Poor soils as the heavy rainfall washes out
the nutrients in the soil.
• Many fast-flowing rivers, which are difficult to cross and swamps infested with
mosquitoes.
• Large hardwood trees like mahogany
trees, which are evergreen and over 50
metres tall with lots of vines and creepers
growing around the trunks of the trees.
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Population Support material
SOCIAL SCIENCE
africa;s weather and climate
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CONCLUSION
These areas are very hot and dry and there
is little chance of obtaining food under
these conditions. People who live here are
often poor. The population densities in
these areas are low as there is no attraction for people to settle in these dry, hot
areas.
africa's weather and climate
Department of Social Development
These areas are too hot and too humid and
it is difficult to settle in a thick forested
area. Natural fruits and roots are available
for food but it is difficult to grow grain
crops to eat. All the dangerous animals and
insects do not make this an area attractive
to live in. Population densities are low in
Equatorial Rainforests.
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Population Support material
Department of Social Development
Private Bag x901, Pretoria 0001
SOUTH AFRICA
www.population.gov.za
Tel: 012 312 7769/7410
Fax: 0123127932
Department of Social Development
Population Support material