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Difficulty: MediumClimatic Controls and World Climate Types

Which climatic control is primarily responsible for the extremely low annual precipitation and frequent coastal fog observed along the Namib Desert of southwestern Africa?

  1. The cold Benguela Current, which chills lower air layers to create a stable atmospheric temperature inversionAnswer
  2. B
    The offshore warm Mozambique Current, which enhances atmospheric instability and rapid evaporation
  3. C
    The seasonal equatorial convergence of moist air masses bringing heavy convective rainfall
  4. D
    High altitude along the coastal margin causing extreme adiabatic expansion and moisture drop

Answer

The cold Benguela Current cooling overriding air layers to create atmospheric stability and temperature inversion.
The presence of the cold Benguela Current along southwestern Africa cools the lower troposphere, forming a strong temperature inversion. This prevents convection and cloud development, causing intense aridity accompanied by frequent coastal advection fog.

Step-by-Step Solution

1
Identify the geographical region and climate characteristics
The coastal Namib Desert of southwestern Africa experiences hyper-arid conditions alongside low surface air temperatures and high morning fog occurrence.
Understanding the physical climate characteristics helps isolate the dominant climatic control operating along this margin.
2
Analyze the impact of ocean currents along the western margins of continents
The cold Benguela Current flows northward along the southwestern coast of Africa, cooling the air layer directly in contact with the sea surface.
Cold ocean currents produce atmospheric thermal inversions where cold, dense air is trapped beneath warm air, preventing air parcel ascent.
3
Evaluate why precipitation is inhibited despite high coastal humidity
Without vertical air ascension (convection), moisture condenses into advection fog instead of forming precipitation-yielding clouds.
Thermal stability induced by cold coastal waters is the primary climatic control behind coastal deserts.

Key Concept

Influence of cold ocean currents as a climatic control on coastal aridity and fog formation
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Topics

Climatic Controls and World Climate Types

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