Climatology Flashcards

Front

What are the three high-pressure cells that dominate South Africa's weather?

Back

• The South Atlantic High

• The Kalahari High

• The South Indian High

Front

Describe the general characteristics of anticyclonic circulation in the Southern Hemisphere.

Back

• Air descends (sinks) and heats adiabatically.

• It circulates in an anti-clockwise direction.

• The descending air causes clear skies with dry, stable air.

Front

How does the Kalahari High Pressure cause dry conditions over the plateau in winter?

Back

A temperature inversion develops below the level of the escarpment. This inversion layer prevents moist air from the Indian Ocean reaching the plateau. The descending air also leads to stable conditions and clear skies.

Front

What is the main effect of the South Indian High Pressure on South Africa's weather?

Back

It causes north-easterly or south-easterly onshore moist air to reach South Africa, bringing rain to the eastern side of the country.

Front

Which front of a mid-latitude cyclone primarily affects South Africa's weather and why?

Back

The cold front is what affects South Africa's weather. This is because the clockwise air movement around the low-pressure cell turns the warm front away from the country.

Front

What weather occurs when the South Atlantic Anticyclone "ridges" south of the country?

Back

Its anti-clockwise air movement drives moist air from the Indian Ocean over the land. This causes cloud and rainfall over the land.

Front

What are Berg Winds and what conditions do they cause?

Back

Warm dry wind that desends on the leeward side of a mountain. They occur when air from the Kalahari High subsides down the escarpment, heating adiabatically. This results in hot, dry conditions, with winter temperatures sometimes exceeding 30°C.

Front

What is a moisture front and what weather is associated with it?

Back

A moisture front is a trough of low pressure that forms over South Africa in summer, extending from the northwest to the southeast. Clouds and rain in the form of line thunderstorms often occur to the east of this front.

Front

What is a Cut-off Low?

Back

It is a part of a mid-latitude cyclone that gets cut off due to the South Atlantic and South Indian high-pressure cells. This forms a low-pressure cell that is trapped over SA

Front

What is the impact of a cut-off low?

Back

It causes set-in rain for several days and is a major cause of flooding in the southern and central parts of the country.