The African climatic variations are as follows:
A. THE SOUTHERN HEMISPHERE'S SUMMER (CLIMATIC CONDITION)
(i) Temperatures
Summer period (January) the sun intensively heats the southern part of Africa
where temperatures rise between 22 degrees
and 27 degrees C with extreme of 32 degrees C and above (in what
is called Bushman land). This period the northern part of Africa is cool, having mean
temperatures of 10degressC in regions such as the Atlas but it increases to 15.5 degrees C in Northern Sahara area.
(ii) Pressures:
From November to April the big isolation over Southern Africa causes low
pressure conditions in this part. But high pressures does develop over the cooler south
Atlantic and Indian Oceans. Over a cooler North Africa high pressure develops, which is
separated from that of continental Europe by a low pressure system over the relatively
warm surface of the Mediterranean sea.
(iii) Winds:
Usually the pattern of wind or air movement over much of Africa is towards the
Equator, from the North-East in the Northern hemisphere and from South-East in the
Southern hemisphere. The two floods of air are derived from sub-tropical cells of high
pressure where air is descending and is consequently warm and dry near the surface.
Here, the descending air in each hemisphere diverges to flow towards the equator and
towards the pole.
And because of the Earth’s rotation this air is diverted to the right in the northern
hemisphere and to the left in the Southern hemisphere. It is even recently when the main
explanation was given for the seasonal occurrence of the rains and total arrangement of
the climatic zones within the tropical Africa. This was based on the Inter-Tropical Front (ITCZ) which is usually formed by airstreams that move to lower latitudes from northeast and south-east.
After coming together the south-easterlies swing round and becomes southwesterlies and the north-easterlies likewise which becomes north-westerlies, when crossing the Equator. This Front (ITCZ) lies, across the African Continent in July each year stretching from Senegal to Eritrea, then shifts south as the sun moves towards the Tropic of Capricorn until January, bringing rains along the Guinea Coast. The ITCZ this period (January) swings far to the south – stretching across Southern Africa especially within latitude 18 degrees South.
These winds from the north high pressure zone penetrate Southwards through the
interior of Africa towards the low pressure zone of the south. High pressure over the
South Atlantic and the south-westerly monsoons oppose their progress in the west.
Along the eastern Coast the North-East Trade and Asiatic monsoonal winds also
penetrate southwards to converge with easterly trade winds and Atlantic-westerlies into
the low pressure system of the south.
It is believed that rain occur in association with the front which is connected with
the humid air along or around the Equator.
(iii) The ITCZ:
The Inter-Tropical Convergence Zone follows the West African Coast, bends
south-wards through the Cameroons and Congo, then eastwards through Botswana and
the Mozambique Coast.
(iv) Air Masses:
The Sahara region, West Africa, northern Congo are influenced by dry, stable air.
A half of eastern Africa receives similar dry, air from Arabia borne by the north-east
trades. Towards the south-east this air mass picks (or has picked) up moisture over theIndian Ocean and becomes warm and moist-Figure . Easterly trade winds bring similar
air to Madagascar, the Natal Coast and the eastern Vield.
Warm, moist, generally unstable air affects most of the Western Coast south of
the Equator. While in the Maghreb region of the north-west coal, moist unstable air
masses are brought by westerly air streams.
B. THE NORTHERN HEMISPHERE'S SUMMER
(i) Temperatures:
On the large land mass of Northern Africa when the sun is overhead between the
Equator and the tropic of cancer, rises temperatures to over 38 degrees C in the Sahara for
example
While, Western, Central Africa by this time occur mean-temperatures between
15.5 degrees C and 26.5 degrees C but in South this is cool with temperatures of about 15.5 degrees C
(ii) Pressures:
A large zone of low pressure exists throughout the Sahara and Arabia which is
broken by occasional minor zones of high pressure on cool Ethiopian Highlands. This
time a high pressure of concentration lies over South Africa to the South of Cameroon.
(iii) Winds:
South-East Trade winds of South Atlantic move across the equator. These winds
are drawn in across the Coast of West Africa by the low pressure zones of the Sahara
which becomes powerful South-West monsoonal winds heavily laden (loaded, burdened
with) with moisture.
The north-east trades retreat to become a weak zone of winds affecting Africa
north of Cancer. This time most of eastern and Central Africa is affected by easterly trade
winds from the Indian Ocean while variable winds associated with the anti-clockwisemovement around the South African high and with the low pressure systems off the
southern Coast, affect Africa South of Capricorn.
(iv) The ITCZ:
The zone lies this time between the weak north-east winds and the strong southwest monsoonal region It extends in almost straight line east-west from the Coast of
Mauritania to the Red Sea shores of the Sudan.
(v) Air Masses:
When Africa north of the ITCZ is under the influence of warm, dry air masses,
warm, moist air brought by the south-west monsoons passes over the whole of West
Africa, penetrating as far as the Ethiopia Highlands to the east and warm, moist, unstable
conditions vary favourable to turbulent (violent, disorderly, uncontrolled) conventional
(convey of heat, movement of heated substances).
Warm, most air also approaches from the south-east moving in over the
Mozambique and East African Coasts.
The Southern part of the continent is affected by cool, moist unstable air brought
by depressions. The conditions described above are the extremes when the sun is at its
extremities in the northern and southern hemispheres.
Throughout the year as the sun and its heat move over the continent between the
tropics, the pressure belts respond and the wind systems weaken or increase in strength
bringing with them associated air masses
Titany answered the question on January 17, 2022 at 13:06