To what extent has altitude influenced the climate of East Africa? 

 

• ‘Candidates should define climate and describe the different climatic zones of East Africa

Climate is the average weather conditions of a place recorded for a long period of time i.e. 30 – 40 years.

The climatic zones of E. Africa include:-

Equatorial climate

East Africa lies astride the Equator and thus experiences the following:

• Temperatures are generally hot and uniform departing little from 27⁰
• There is great uniformity of temperature throughout the year ranging between 25⁰C- 28°C.
• The diurnal range is much more marked than the seasonal one, it’s small and sometimes attaining only 8⁰C while the annual range barely exceeds 2°C.
• Convectional rainfall is usually received during the afternoon and evening and is often accompanied by thunderstorms and lightening for example around the L. Victoria basin at Jinja, Entebbe and Kampala in Uganda, Bukoba and Mwanza in Tanzania.
• Receives heavy and well distributed rainfall throughout the year of between 1000 – 2000mm per annum
• Characterized by two rainfall maxima with peaks in March and November (Bi-modal pattern) where the first is heavier than the other.
• There is no dear marked dry season since rainfall is received throughout the year.
• Constantly high humidity (80%) throughout the year due to high rate of evaporation.
• Characterized by a thick cloud cover throughout the year due to high rates of evaporation and condensation.
• Equatorial areas are affected by air masses that converge along the I.T.C.Z though there may be long periods of calms or light winds.
• Mainly experiences convectional type of rainfall

 

Savanna climate

It’s found between a transition zone between the equatorial belt and the hot desert.

It’s experienced majorly in Central and Northern Uganda, South and Western Tanzania, coast.al areas of East Africa etc.

Characteristics of Savanna climate

• There is alternating dry and wet season as a result of the apparent movement of the sun.
• Maximum temperatures of up to 32°C are attained before the onset of the rains as a result of the dry air and cloudless skies.
• Receives moderate rainfall of over 750mm – 1000m. But the rains are unreliable from year to year.
• Temperatures range between 23°C and 27⁰
• Because of limited cloud cover, there is a high marked diurnal temperature range (15⁰C) The annual temperature range is relatively low at between 7°- 8°C.
• Receives convectional rainfall alternating with a dry winter which either the trades or  stable air masses are dominant The rains are normally short-lived and torrential.
• Low humidity during the dry season and relatively high during the rainy season.

 

Montane climate

This covers the Highland areas of East Africa: mountains – Kilimanjaro, Kenya, Mt. Abadares and Mau ranges, parts of Western Uganda (Rwenzori and Muhavura), Elgon in Eastern Uganda, Southern highlands of Tanzania, etc.

 Characteristics montane climate

• High rain fall totals of over 1000mm- 1500mm per annum
• Receive orographic type of Rainfall
• Has cool temperatures of less than19°C

Semi- Arid and Arid climate

Majorly found in the North-East and Nothern Kenya., North East Uganda, Central and Western Tanzania etc.

Characteristics of semi-Arid anti Arid climate                                                                                                                      ·

• Low/ limited rainfall totals of less than 700mm
• Unreliable rainfall throughout the year
• High temperatures of about 30°C
• Large diurnal temperature range of above 5⁰C
• High evaporation rates due to hot temperatures
• Low/limited cloud cover.
• Low humidity level of less than 30%

 

Candidates should bring out the influence altitude on climate clearly

NB Altitude is the height above Sea level.

• Areas of high altitude e.g. the highland and mountains like Kenya. Kilimanja.ro, southern highlands of Tanzania experience cool temperature because temperatures decrease with increasing altitude due to rarefied air; while low altitude areas like  the coastal regions, Rift valley floor, mountain  foothills experience  hot temperatures due to a lot of dust particles, water molecules and carbon dioxide that absorb heat that’s radiate in the lower altitude
• The highland areas e.g. mountain tops experience low pressure as pressure reduces with increasing altitude while in low altitude areas, pressure is high because of the big column of air pressing over the Earth s surface.
• The highland areas /mountainous areas like Rwenzori mountain, Kilimanjaro mountain receive heavy rainfall (1000mm -1500mm)
• Higher plateau areas (central plateau) receive moderate rainfall ranging between 700mm –1000mm
• The lower plateau of East Africa e.g. Nyika plateau are dry i.e. receive rainfall totals of less than 700mm
• Low altitude areas experience high humidity due to high evaporation – transpiration levels and hot temperatures while high altitude areas experience low humidity levels due to cool temperatures.

Candidate should bring out other factors

• Prevailing winds: North East trade winds from Arabia desert are dry and bot leading to arid conditions in Northern Kenya and North- Eastern Uganda.

The south East trade winds that are warm and moist bring rainfall to the Northern shores of Lake Victoria and the coastal areas of East Africa.

The warm moist Westeries bring rainfall on the western slopes of mountain Rwenzori and aridity on the lee ward side of the mountain Rwenzori (Albert flats)

• Latitude: East Africa lies a stride the Equator. It’s location explains the generally hot temperatures experienced though out the It also explains the double rainfall pattern maxima in the low latitudinal zone while one single rainfall peak in the southern Tanzania is being experienced and one rainfall peak in areas of Northern Uganda because in they are relatively away from the Equator.
• Presence of water bodies: Large lakes g. Lake Victoria, Kyoga and proximity to the Indian ocean experience heavy rainfall, high humidity as opposed to those areas that are far from these big water bodies.
• Presence of vegetation cover: Forests maintain heavy rainfall, high humidity, and moderate temperatures throughout the year unlike areas with scanty vegetation.
• Human activities have modified the East African climate through deforestation, industrial pollution, agricultural activities, over grazing etc.