SUB-TROPICAL ANTI-CYCLONES Flashcards
climate and weather
Adiabatic heating
Heating which occurs when the air is compressed.
Anticyclones
A large high-pressure cell of stable subsiding air.
Berg wind
A local wind that blows down the escarpment from the plateau to the
coast, bringing hot, dry weather.
Coastal low:
A localised low-pressure system that brings changeable weather to
a coastal region.
Cut-off low
pressure system:
A low-pressure cell which has become completely displaced over
the land and moves independently of any air around it
Inversion layer:
A layer of air where temperature increases with increasing altitude.
Kalahari High:
A large high-pressure cell over South Africa’s interior; it is
responsible for clear skies and dry conditions in winter.
Line thunderstorm
Summer storms that occur when a trough of low pressure develops
over the interior between the thermal low and coastal low.
Moisture front
A boundary over the interior where warm, moist air blowing from the
north-east (Indian Ocean) meets cool, dry air from the south-west
(Atlantic Ocean).
Ridge:
An extension of a high-pressure cell when the isobars extend along
the east -west axis. This happens when the south Atlantic high
sometimes extends behind a passing cold front in winter or around
the southern tip of South Africa in summer.
South Atlantic
High-Pressure:
A large high-pressure cell over the Atlantic Ocean; it sometimes
pushes cold fronts inland.
South Indian High
Pressure:
A large high-pressure cell over the Indian Ocean; it is responsible
for rain in the eastern half of South Africa.
Sub-tropical
anticyclones
High-pressure cells of the general circulation centred at about 30ᵒ
North and South.
Thermal low-pressure:
A thermal low-pressure that develops over the central interior of
Southern Africa in the summer.
Trough:
Occurs between two low pressure cells or an extension of a low-pressure cell.
