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Difficulty: MediumClimate and Climatic Regions of Nigeria

During the month of July, the Inter-Tropical Discontinuity (ITD) reaches its northernmost position over West Africa, situated near latitude 20∘N20^\circ\text{N}. What is the primary meteorological effect of this displacement on the weather conditions across northern Nigeria?

  1. Northern Nigeria comes under the dominant influence of the moist Tropical Maritime (mT) air mass, ushering in its peak rainy season.Answer
  2. B
    Northern Nigeria is brought under the exclusive control of the dry Tropical Continental (cT) air mass, inducing severe drought conditions.
  3. C
    Northern Nigeria receives a brief August dry spell due to the complete retreat of the South-West Monsoon winds.
  4. D
    Northern Nigeria experiences its lowest annual temperature due to the full effect of the dust-laden Harmattan wind.

Answer

Northern Nigeria comes under the dominant influence of the moist Tropical Maritime (mT) air mass, ushering in its peak rainy season.
In July, the ITD migrates to its furthest northern position near 20∘N20^\circ\text{N}. Because moisture-bearing Tropical Maritime (mT) winds flow from the south beneath the ITD boundary, virtually all of Nigeria—including the far north—is covered by humid air, marking the peak of the northern rainy season.

Step-by-Step Solution

1
Analyze the position of the Inter-Tropical Discontinuity (ITD) in July.
In July, the ITD moves to its northernmost limit (around 20∘N20^\circ\text{N} to 22∘N22^\circ\text{N}).
The seasonal movement of the ITD follows the overhead position of the sun towards the Tropic of Cancer.
2
Determine the dominant air mass south of the ITD.
The moist Tropical Maritime (mT) air mass originating from the South Atlantic lies south of the ITD.
As the ITD pushes north, it pulls the moist South-West Monsoon winds deep into the interior and northern parts of Nigeria.
3
Deduce the resulting weather in northern Nigeria.
Northern Nigeria experiences high relative humidity, heavy cloud cover, and peak annual precipitation.
The deep layer of moisture-laden air promotes convection and precipitation in the northern region.

Key Concept

Inter-Tropical Discontinuity (ITD) and Seasonal Air Mass Movement in Nigeria
Estimated Time:1m 0s
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Topics

Climate and Climatic Regions of Nigeria

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