GRADE 11 GEOGRAPHY IEB SYLLABUS
This summary covers:
1. The Atmosphere
2. Development Geography
This summary only contains 2/5 chapters of the Grade 11 Geography IEB Syllabus. The two
chapters it doesn’t contain is: Geomorphology, Resources + Sustainability and Mapwork.
,Grade 11 Geography IEB Syllabus
THE ATMOSPHERE
Aspect:
- As a result of the difference in heating at different latitudes, places in the southern
hemisphere that face the Equator (north) receive more sunlight, this is known as
aspect.
- This causes local and regional differences in the amount of heat received on north-
facing and south-facing slopes.
Tri-cellular Circulation:
- Describes a system of circulatory cells that move air about the planet.
Hadley cells
- Air at the equator is heated and ascends vertically.
- Air reaches the top of the troposphere and diverges polewards.
- Air, that lost some of its initial heat, sinks.
- Air diverges at the surface and flows either back towards the Equator (creating the
first cell of the tri-cellular model) or is pushed into the subtropics (and resulting the
second cell – the ferrel cell).
, Grade 11 Geography IEB Syllabus
Tropical easterlies
- Surface winds that occur in the Hadley cell and flow from east to west
- They pull the diverging air at the subtropics back towards the Equator
- Subtropical westerlies
- Flow polewards of the high pressure belt
- Push part of the diverging air mass into the Ferrel Cell and on towards the poles.
- Rising warm, moist air
Ferrel cells
- The second cell
- Warmer air moving out of the subtropics collide with cold air flowing down from the
poles called the polar front.
- Warmer, more humid air pushed by the subtropical westerlies overrides the colder,
dry air drawn down by the polar easterlies.
- This creates an area of low pressure named the subpolar low pressure belt.
- The sporadic mixing of these otherwise separate air masses is responsible for the
formation of mid-latitude cyclones that help account for WC's rainfall.
- Having risen along the polar front, the ascending air diverges along the upper edge
of the troposphere.
- Some of this air flows back towards the Hadley cell, it will converge with the air
moving out of the equatorial region.
- Remaining air mass will be pulled into the final cell of the tri-cellular model, the Polar
cell.
- Chilled by cold conditions, the now heavy air will descend about the poles.
Polar cells
- Air at the northernmost latitudes is extremely cold, sinks under its great density.
- Polar easterlies push this cold, dry sinking air back towards the pole front, where it
collides with the arriving subtropical air.
- Descending cool, dry air
This summary covers:
1. The Atmosphere
2. Development Geography
This summary only contains 2/5 chapters of the Grade 11 Geography IEB Syllabus. The two
chapters it doesn’t contain is: Geomorphology, Resources + Sustainability and Mapwork.
,Grade 11 Geography IEB Syllabus
THE ATMOSPHERE
Aspect:
- As a result of the difference in heating at different latitudes, places in the southern
hemisphere that face the Equator (north) receive more sunlight, this is known as
aspect.
- This causes local and regional differences in the amount of heat received on north-
facing and south-facing slopes.
Tri-cellular Circulation:
- Describes a system of circulatory cells that move air about the planet.
Hadley cells
- Air at the equator is heated and ascends vertically.
- Air reaches the top of the troposphere and diverges polewards.
- Air, that lost some of its initial heat, sinks.
- Air diverges at the surface and flows either back towards the Equator (creating the
first cell of the tri-cellular model) or is pushed into the subtropics (and resulting the
second cell – the ferrel cell).
, Grade 11 Geography IEB Syllabus
Tropical easterlies
- Surface winds that occur in the Hadley cell and flow from east to west
- They pull the diverging air at the subtropics back towards the Equator
- Subtropical westerlies
- Flow polewards of the high pressure belt
- Push part of the diverging air mass into the Ferrel Cell and on towards the poles.
- Rising warm, moist air
Ferrel cells
- The second cell
- Warmer air moving out of the subtropics collide with cold air flowing down from the
poles called the polar front.
- Warmer, more humid air pushed by the subtropical westerlies overrides the colder,
dry air drawn down by the polar easterlies.
- This creates an area of low pressure named the subpolar low pressure belt.
- The sporadic mixing of these otherwise separate air masses is responsible for the
formation of mid-latitude cyclones that help account for WC's rainfall.
- Having risen along the polar front, the ascending air diverges along the upper edge
of the troposphere.
- Some of this air flows back towards the Hadley cell, it will converge with the air
moving out of the equatorial region.
- Remaining air mass will be pulled into the final cell of the tri-cellular model, the Polar
cell.
- Chilled by cold conditions, the now heavy air will descend about the poles.
Polar cells
- Air at the northernmost latitudes is extremely cold, sinks under its great density.
- Polar easterlies push this cold, dry sinking air back towards the pole front, where it
collides with the arriving subtropical air.
- Descending cool, dry air
