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
