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Difficulty: MediumClimate and Climatic Regions of Nigeria

The coastal belt of southern Nigeria experiences a distinct climate marked by two rainfall peaks in June and September, separated by a brief dry spell in August commonly known as the 'August Break'. Which of the following factors primarily accounts for this double rainfall maximum?

  1. The temporary southward movement of the Inter-Tropical Discontinuity (ITD) during mid-summerAnswer
  2. B
    The year-round dominance of the dry North-East Trade Winds over coastal southern regions
  3. C
    The continuous influence of high orographic barriers along the Atlantic coastline
  4. D
    The sharp drop in sea surface temperatures caused by the cold Canaries Current

Answer

The temporary southward movement of the Inter-Tropical Discontinuity (ITD) during mid-summer primarily accounts for the double rainfall maximum in southern Nigeria.
The double rainfall maximum in southern Nigeria occurs because the moist South-West Trade Winds bring a primary peak of rainfall as the ITD migrates northwards in June/July, followed by a second peak as the ITD retreats southwards in September. In August, when the ITD is at its northernmost position, the coastal zone experiences stable air and a temporary lull in heavy rainfall known as the August Break.

Step-by-Step Solution

1
Analyze the climatic characteristics of southern Nigeria's Sub-Equatorial zone.
Southern coastal Nigeria experiences a double rainfall regime with peaks in June/July and September.
Rainfall distribution in West Africa depends directly on the seasonal migration of the Inter-Tropical Discontinuity (ITD).
2
Examine the movement of the ITD during July and August.
As the ITD moves to its furthest northern extent (around latitude 20°N to 22°N), the zone of maximum convective rainfall shifts inland into central and northern Nigeria.
This leaves the southern coastal strip under a temporary stable marine surface atmospheric layer, producing the 'August Break' between the two rainfall maxima.

Key Concept

Double Rainfall Maximum and ITD Dynamics in Southern Nigeria
Estimated Time:1m 0s
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Topics

Climate and Climatic Regions of Nigeria

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