GEOGRAPHY GRADE 12 NOTES
KEY: Study the notes and practice a lot of question papers for great grades. I got you!
1. Synoptic Weather Map Interpretation
• A synoptic weather map shows weather conditions over a large area at a specific time.
• It includes information like temperature, wind speed and direction, pressure,
precipitation, and cloud cover.
• Isobars are lines on the map that connect points of equal atmospheric pressure.
• Low pressure areas (cyclones) have isobars with decreasing pressure towards the
center; high pressure areas (anticyclones) have increasing pressure towards the center.
• Weather stations on the map show symbols for wind direction, wind speed (in knots),
temperature, dew point, cloud cover, and precipitation.
• Reading these maps helps predict weather patterns like storms, rain, or clear skies.
2. Global Winds / Planetary Winds
• Global winds are large-scale wind systems that circulate around the Earth due to
uneven heating.
• The Earth’s rotation causes winds to deflect (Coriolis effect): to the left in the Southern
Hemisphere.
• There are three main global wind belts:
• Tropical Easterlies (Trade Winds): Blow from the subtropical high-pressure
belts towards the equator (0° to 30° latitude).
• Westerlies: Blow from the subtropical high-pressure belts towards the subpolar
low-pressure belts (30° to 60° latitude).
• Polar Easterlies: Blow from the poles towards the subpolar low-pressure belts
(60° to 90° latitude).
• These winds help distribute heat and moisture around the planet and influence weather
and climate patterns.
Cyclones
• Cyclones are low-pressure systems with rising air and rotating winds.
• They bring stormy weather like strong winds and heavy rain.
There are two main types: mid-latitude cyclones and tropical cyclones.
1.2.1 Mid-latitude Cyclones
• Also called temperate or extra-tropical cyclones.
, • Form between 40° and 60° latitude in both hemispheres.
• Move from west to east, driven by westerly winds.
• Have warm fronts, cold fronts, and warm sectors.
• Weather includes overcast skies, thunderstorms near cold fronts, and cooler
temperatures behind cold fronts.
• Affect South Africa mostly in winter.
1.2.2 Tropical Cyclones
• Also called hurricanes, typhoons, or willy-willies depending on the region.
• Form between 5° and 30° latitude over warm tropical oceans.
• Move from east to west, driven by trade winds.
• Have a calm eye at the center surrounded by strong thunderstorms.
• Bring violent winds, heavy rain, and storm surges.
• Affect coastal areas mostly in summer and autumn.
1.2.3 Characteristics of Mid-latitude and Tropical Cyclones
Characteristic Mid-latitude Cyclone Tropical Cyclone
Other names Temperate cyclone, frontal Hurricane, typhoon, willy-willy
depression
Formation area 40°–60° latitude 5°–30° latitude over tropical
oceans
Movement West to east East to west
Season All year round, winter in South Summer to autumn
Africa
Weather Warm front, cold front, warm Eye, intense thunderstorms
features sector
Areas affected Western side of continents Eastern side of continents
1.3 Factors Affecting the South African Climate
South Africa’s climate is influenced mainly by three factors:
• The surrounding oceans and ocean currents
• The high plateau on which most of the country lies
• The subtropical high pressure belt
1.3.1 Impact of the Ocean and Ocean Currents
KEY: Study the notes and practice a lot of question papers for great grades. I got you!
1. Synoptic Weather Map Interpretation
• A synoptic weather map shows weather conditions over a large area at a specific time.
• It includes information like temperature, wind speed and direction, pressure,
precipitation, and cloud cover.
• Isobars are lines on the map that connect points of equal atmospheric pressure.
• Low pressure areas (cyclones) have isobars with decreasing pressure towards the
center; high pressure areas (anticyclones) have increasing pressure towards the center.
• Weather stations on the map show symbols for wind direction, wind speed (in knots),
temperature, dew point, cloud cover, and precipitation.
• Reading these maps helps predict weather patterns like storms, rain, or clear skies.
2. Global Winds / Planetary Winds
• Global winds are large-scale wind systems that circulate around the Earth due to
uneven heating.
• The Earth’s rotation causes winds to deflect (Coriolis effect): to the left in the Southern
Hemisphere.
• There are three main global wind belts:
• Tropical Easterlies (Trade Winds): Blow from the subtropical high-pressure
belts towards the equator (0° to 30° latitude).
• Westerlies: Blow from the subtropical high-pressure belts towards the subpolar
low-pressure belts (30° to 60° latitude).
• Polar Easterlies: Blow from the poles towards the subpolar low-pressure belts
(60° to 90° latitude).
• These winds help distribute heat and moisture around the planet and influence weather
and climate patterns.
Cyclones
• Cyclones are low-pressure systems with rising air and rotating winds.
• They bring stormy weather like strong winds and heavy rain.
There are two main types: mid-latitude cyclones and tropical cyclones.
1.2.1 Mid-latitude Cyclones
• Also called temperate or extra-tropical cyclones.
, • Form between 40° and 60° latitude in both hemispheres.
• Move from west to east, driven by westerly winds.
• Have warm fronts, cold fronts, and warm sectors.
• Weather includes overcast skies, thunderstorms near cold fronts, and cooler
temperatures behind cold fronts.
• Affect South Africa mostly in winter.
1.2.2 Tropical Cyclones
• Also called hurricanes, typhoons, or willy-willies depending on the region.
• Form between 5° and 30° latitude over warm tropical oceans.
• Move from east to west, driven by trade winds.
• Have a calm eye at the center surrounded by strong thunderstorms.
• Bring violent winds, heavy rain, and storm surges.
• Affect coastal areas mostly in summer and autumn.
1.2.3 Characteristics of Mid-latitude and Tropical Cyclones
Characteristic Mid-latitude Cyclone Tropical Cyclone
Other names Temperate cyclone, frontal Hurricane, typhoon, willy-willy
depression
Formation area 40°–60° latitude 5°–30° latitude over tropical
oceans
Movement West to east East to west
Season All year round, winter in South Summer to autumn
Africa
Weather Warm front, cold front, warm Eye, intense thunderstorms
features sector
Areas affected Western side of continents Eastern side of continents
1.3 Factors Affecting the South African Climate
South Africa’s climate is influenced mainly by three factors:
• The surrounding oceans and ocean currents
• The high plateau on which most of the country lies
• The subtropical high pressure belt
1.3.1 Impact of the Ocean and Ocean Currents
