,Contents
South Indian High Pressure / South Atlantic High Pressure (Subtropical Anticyclones) ........ 2
Location / How it affects SA (seasonal shifts are a result of shift in ITCZ) ............................. 2
General characteristics of anticyclones: ................................................................................ 2
How Oceans affect Anticyclonic conditions: .......................................................................... 2
Travelling disturbances: ............................................................................................................ 4
1. Moisture Front (summer) ............................................................................................... 4
2. Coastal Low Pressure (anytime) ..................................................................................... 5
3. Cut-off low (anytime) ...................................................................................................... 6
4. Berg winds....................................................................................................................... 6
5. The Cape Doctor: ............................................................................................................ 7
Micro-Climates (experienced in small area where climate differs from surrounding area) .. 8
1. Valley Climate: ................................................................................................................ 8
Aspect ................................................................................................................................. 8
Anabatic / Katabatic winds ................................................................................................. 9
Inversion layer (Thermal Belt) .......................................................................................... 10
Frost Pocket ...................................................................................................................... 10
Radiation Fog .................................................................................................................... 11
2. Urban Climate: .............................................................................................................. 11
Urban vs Rural Climate ..................................................................................................... 11
Urban Heat Islands ........................................................................................................... 12
Pollution Domes ............................................................................................................... 13
Management strategies of Heat Islands / Pollution Domes ............................................ 14
1
,South Indian High Pressure / South Atlantic High Pressure (Subtropical
Anticyclones)
Location / How it affects SA (seasonal shifts are a result of shift in
ITCZ)
SAHP SIHP
Summer Strongly developed Moves further south
Blocks MLCs from reaching Warm/moist NE winds blow
south coast = cool dry into interior = summer
summers rainfall
Winter Weakens Moves further north
MLCs move north. Cold Warm/moist air trapped
fronts affect SA = cool wet under inversion layer = dry
conditions in SW parts of SA interior / wet east coast
General characteristics of anticyclones:
H – H.P
A – Anticlockwise rotation of air
S – Sinking air (cool + dry)
O – outwards (divergence)
How Oceans affect Anticyclonic conditions:
• Air blowing from the east over warm Agulhas current is warmer and can hold more
water vapor than cooler drier air blowing over cold Benguela current on the west.
• Therefore, east coast = more humid / warm
West coast = colder and dryer
NB:
Maritime climate:
• Impacted by both ocean + continent
• Small temperature range as a result of slow heating / cooling of the ocean
Continental:
• High temperature range due to rapid heating / cooling of the earth
2
, Kalahari High + How it affects Inversion Layer
Kalahari High:
• High pressure cell which intensifies over the interior of southern Africa (in winter).
• Caused by cold subsiding air that sits close to the land.
WINTER
• Kalahari high + SIHP are well developed
• Cool dry air descends on top of inversion layer (under influence of anticyclones)
• Thus, high pressure cells push down on inversion layer below escarpment
• Warm / moist air trapped and unable to reach interior = dry winters in interior / winter
rainfall on east coast
SUMMER
• Warmer / moist / unstable air rises creating a thermal low at the surface (replacing
Kalahari High)
• Kalahari High + SIHP weaken / displaced higher in atmosphere
• Allows inversion layer to rise above escarpment
• Warm / moist air is able to reach interior = summer rainfall over interior
3
South Indian High Pressure / South Atlantic High Pressure (Subtropical Anticyclones) ........ 2
Location / How it affects SA (seasonal shifts are a result of shift in ITCZ) ............................. 2
General characteristics of anticyclones: ................................................................................ 2
How Oceans affect Anticyclonic conditions: .......................................................................... 2
Travelling disturbances: ............................................................................................................ 4
1. Moisture Front (summer) ............................................................................................... 4
2. Coastal Low Pressure (anytime) ..................................................................................... 5
3. Cut-off low (anytime) ...................................................................................................... 6
4. Berg winds....................................................................................................................... 6
5. The Cape Doctor: ............................................................................................................ 7
Micro-Climates (experienced in small area where climate differs from surrounding area) .. 8
1. Valley Climate: ................................................................................................................ 8
Aspect ................................................................................................................................. 8
Anabatic / Katabatic winds ................................................................................................. 9
Inversion layer (Thermal Belt) .......................................................................................... 10
Frost Pocket ...................................................................................................................... 10
Radiation Fog .................................................................................................................... 11
2. Urban Climate: .............................................................................................................. 11
Urban vs Rural Climate ..................................................................................................... 11
Urban Heat Islands ........................................................................................................... 12
Pollution Domes ............................................................................................................... 13
Management strategies of Heat Islands / Pollution Domes ............................................ 14
1
,South Indian High Pressure / South Atlantic High Pressure (Subtropical
Anticyclones)
Location / How it affects SA (seasonal shifts are a result of shift in
ITCZ)
SAHP SIHP
Summer Strongly developed Moves further south
Blocks MLCs from reaching Warm/moist NE winds blow
south coast = cool dry into interior = summer
summers rainfall
Winter Weakens Moves further north
MLCs move north. Cold Warm/moist air trapped
fronts affect SA = cool wet under inversion layer = dry
conditions in SW parts of SA interior / wet east coast
General characteristics of anticyclones:
H – H.P
A – Anticlockwise rotation of air
S – Sinking air (cool + dry)
O – outwards (divergence)
How Oceans affect Anticyclonic conditions:
• Air blowing from the east over warm Agulhas current is warmer and can hold more
water vapor than cooler drier air blowing over cold Benguela current on the west.
• Therefore, east coast = more humid / warm
West coast = colder and dryer
NB:
Maritime climate:
• Impacted by both ocean + continent
• Small temperature range as a result of slow heating / cooling of the ocean
Continental:
• High temperature range due to rapid heating / cooling of the earth
2
, Kalahari High + How it affects Inversion Layer
Kalahari High:
• High pressure cell which intensifies over the interior of southern Africa (in winter).
• Caused by cold subsiding air that sits close to the land.
WINTER
• Kalahari high + SIHP are well developed
• Cool dry air descends on top of inversion layer (under influence of anticyclones)
• Thus, high pressure cells push down on inversion layer below escarpment
• Warm / moist air trapped and unable to reach interior = dry winters in interior / winter
rainfall on east coast
SUMMER
• Warmer / moist / unstable air rises creating a thermal low at the surface (replacing
Kalahari High)
• Kalahari High + SIHP weaken / displaced higher in atmosphere
• Allows inversion layer to rise above escarpment
• Warm / moist air is able to reach interior = summer rainfall over interior
3
