GEOGRAPHY
Grade 11
LEARNER SUPPORT
Revision Term 1 - 2021
THE ATMOSPHERE
This revision program is designed to assist you in revising the critical content and skills
covered during TERM 1. The purpose is to prepare you to understand the key concepts and
to provide you with an opportunity to establish the required standard and the application
of the knowledge necessary to succeed in the GRADE 11 examination. The content in this
revision booklet is mostly presented by means of mind maps. This will help you to
understand the content easier and also see the relationship between the topics. This
revision booklet should be used in conjunction with the lessons of term 1.
CONTENT
1
The Earth’s energy balance
3
2
Global air circulation
4
3
Africa’s weather and climate
9
4
Droughts and desertification
11
Activities
Activity 1 : The Earth’s energy balance: Seasons
12
Activity 2 : Global air circulation
13
Activity 3 : Monsoon winds
14
Activity 4 : Desertification
15
Activity 5 : Synoptic weather maps
16
Activity 6 : Concepts
17
Geography revision booklet 2021
Grade 11 Term 1
1.
1.1
THE EARTH’S ENERGY BALANCE
The unequal heating of the atmosphere and the transfer of energy
Areas closer to the Equator do
not get hotter and hotter. Winds
and ocean currents transfer
surplus energy from equatorial
areas to the poles. Therefore a
heat balance is maintained on
Earth.
1.2
Significance of the Earth’s axis and revolution around the sun
Geography revision booklet 2021
Grade 11 Term 1
You must know the following:
• Seasons in each hemisphere
• Position of the sun at each season
• Length of day and night
• Solstices and equinoxes
2.
GLOBAL AIR CIRCULATION
2.1
What are high and low pressures?
2.2
Relationship between air temperature, air pressure and wind
•
•
•
•
•
Hot air expands and
rises
Leads to low pressure
on Earth’s surface
Cold air is dense and
heavy
Sinks to Earth’s surface
Air (wind) moves from
high pressure to low
pressure
Geography revision booklet 2021
Grade 11 Term 1
2.3
Pressure gradient, Coriolus force and geostrophic flow
2.3.1 Pressure gradient
2.3.1 Coriolus Force
Geography revision booklet 2021
Grade 11 Term 1
2.3.3 Geostrophic flow
It is an upper air wind that blows parallel to the isobars and at right angles to the
pressure gradient
Geography revision booklet 2021
Grade 11 Term 1
2.4
World Pressure belts, Tri-cellular circulation, Winds related to global
air circulation
You must know the following:
• The names of each of the pressure belts
• Are the pressure belts High or Low pressure
• How each of the pressure belts are formed
• The winds found at each of the belts
• Deflection of the winds and why
• The names of each of tri-cellular cells
• How each of the cells are formed
Geography revision booklet 2021
Grade 11 Term 1
2.5
Air mass characteristics
2.6
Monsoon winds
It is a seasonal wind characterized by a complete reversal of wind direction between summer
and winter, which results in totally different weather conditions especially rainfall between
summer and winter.
Geography revision booklet 2021
Grade 11 Term 1
2.7
Föhn winds
Föhn is a name used for a that
starts from the windward side of a
mountainous area and descends
on the leeward side of mountains
as a dry, hot wind.
3.
3.1
AFRICA’S WEATHER AND CLIMATE
Africa’s climate regions
Geography revision booklet 2021
Grade 11 Term 1
3.3
The role of oceans in climate control in South Africa
3.4
El Niño and La Niña
You must be able to distinguish between El Niño and La Niña
Geography revision booklet 2021
Grade 11 Term 1
4.
DROUGHTS AND DESERTIFICATION
AREAS AT RISK
DEFINITIONS
What is drought?
Drought is defined as an
extended period of below
average rainfall.
What is desertification?
Desertification is defined
as a process of land
degradation in mainly arid,
semi-arid and sub-humid
dry areas
CAUSES OF DROUGHTS
• Excessive build-up of heat on the Earth’s surface
• Meteorological changes, like a reduction in the
amount of water vapour available
• Reduced cloud cover leading to great
evaporation rates
• Less rainfall due to weather patterns changing
• Climate change
• Oceanic and atmospheric weather cycles such as
the El Niño.
EFFECTS OF DROUGHTS AND
DESERTIFICATION
•
•
•
•
•
•
Fewer crops means less food.
Unemployment
Rural depopulation
Soil erosion
Fires due to dry vegetation
Less exports
CAUSES OF DESERTIFICATION
• Climate related processes, like global
climate change.
• Farming is done on unsuitable land.
• Poor agricultural practices such as
overgrazing
• Deforestation
• Soil erosion
• Lack of knowledge causes people to
degrade land
• Policies leading to unsustainable use of
resources
MANAGEMENT OF DROUGHTS
AND DESERTIFICATION
• Policy approaches that promote
sustainable resource use.
• Research I to prediction of droughts
• Water restrictions
• Recycling of water
• Construct dams
You must be able to answer the following questions
•
•
•
•
•
What is a drought (definition)?
What is desertification (definition)?
Where are the areas at risk?
What are the effects of droughts and desertification?
How can droughts and desertification be managed?
Geography revision booklet 2021
Grade 11 Term 1
REVISION ACTIVITIES
REVISION ACTIVITY 1 : SEASONS
The questions are based on the diagram
Complete the table
DATE
Sun direct over
which latitude
Season in
S Hemisphere
Season in
N Hemisphere
A
B
C
D
Geography revision booklet 2021
Grade 11 Term 1
REVISION ACTIVITY 2 : WORLD PRESSURE BELTS, TRI-CELLULAR
CIRCULATION, WINDS RELATED TO GLOBAL AIR CIRCULATION
Add the following to the diagram:
•
•
•
•
The pressure belts 1-7 (state Low- or High pressure)
How the pressure belts 8-11 were formed
The cells 12-14 and how they were formed
The winds 15-20
Geography revision booklet 2021
Grade 11 Term 1
REVISION ACTIVITY 3 : MONSOON WINDS
The questions are based on the map of monsoon winds in India.
3.1
What is a monsoon wind?
(1x2)
(2)
3.2
(a) What season, winter or summer, is shown by the diagram
(b) Give ONE reason for your answer in question 3.2
(1x1)
(1x2)
(1)
(2)
3.3
(a) Would a high pressure be found at A or at B?
(b) Give ONE reason for your answer in question 3.4
(1x1)
(1x2)
(1)
(2)
3.4
Explain why heavy rainfall occur during the season shown on the map.
(1x2)
(2)
(4x2)
(8)
3.5
In a paragraph of approximately EIGHT lines, explain how the
monsoon winds are formed.
Geography revision booklet 2021
Grade 11 Term 1
REVISION ACTIVITY 4 : DESERTIFICATION
The questions are based on map of Africa below which shows the Sahara desert spreading
southward, known as the Sahel.
4.1
As what is the spreading of deserts known?
(1x1)
(1)
4.2
Make use of an atlas and identify 3 countries in the Sahel where the
Sahara desert had spread.
(3x1)
(3)
In a paragraph of approximately EIGHT lines, explain the causes of
desertification.
(4x2)
(8)
Give THREE ways in which desertification be managed?
(3x2)
(6)
4.3
4.4
Geography revision booklet 2021
Grade 11 Term 1
REVISION ACTIVITY 5 : SYNOPTIC WEATHER MAPS
The questions are based on the synoptic weather map
3.1
Does the synoptic weather map show summer or winter conditions?
(1x1)
(1)
3.2
Give TWO reasons for your answer in question 3.1
(2x2)
(4)
3.3
(a) Is A a high or a low pressure?
(b) Give ONE reason for your answer in question 3.3 (a)
(1x1)
(1x2)
(1)
(2)
3.4
Identify the pressure gradient at B-B and C-C
(2x1)
(2)
3.6
Describe the wind circulation at D.
(1x2)
(2)
3.7
To which pressure belt does E belong?
(4x2)
(8)
3.8
In which direction does F move?
(1x1)
(1)
Geography revision booklet 2021
Grade 11 Term 1
3.9
Give the following with regard to the weather station at G. The station is
enlarged on the right hand side of the synoptic weather map:
(a) Cloud cover
(b) Wind direction
(c) Wind speed
(d) Air temperature
(e) Dewpoint temperature
(5x1)
REVISION ACTIVITY 6 : THE ATMOSPHERE - CONCEPTS
Give the correct definition/description for each of the following concepts.
Concept
1
2
3
4
5
6
7
8
9
10
12
13
14
15
16
17
Definition/Description
Insolation
Solstices
Equinox
Pressure gradient
Gentle pressure
gradient
Steep pressure
gradient
Coriolus force
High pressure
Low pressure
Geostrophic flow
Equatorial low
pressure
Sub-tropical high
pressure
Sub-polar low
pressure
Polar high pressure
Hadley cell
Ferrel cell
Geography revision booklet 2021
Grade 11 Term 1
(5)
18
19
Polar cell
Air mass
20
Monsoon wind
21
Föhn wind
22
El Niño
23
La Niña
24
Desertification
25
Drought
Follow this link or scan the QR code to access the telematics broadcast of Grade 11 The
Atmosphere:
https://youtu.be/XeAcywIFWAs
Geography revision booklet 2021
Grade 11 Term 1