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How do trade winds influence Type A tropical climates?
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Köppen climate classification
The major climatic types are based on patterns of average precipitation, average temperature, and natural vegetation. This map depicts the world distribution of climate types based on the classification originally invented by Wladimir Köppen in 1900.
In the Köppen climate classification, Type A tropical climates are primarily controlled by the seasonal fluctuations of the trade winds, the intertropical convergence zone (ITCZ), and the Asian monsoon.1
The influence of trade winds on these climates varies by type:
- Tropical Monsoon and Trade-Wind Littoral Climate (Am): In regions such as the Americas and Africa, this climate is driven by trade winds. As moist trade-wind air ascends mountain chains, it produces orographic precipitation on narrow coastal strips. Seasonal shifts in the intensity and position of these winds create short, moderately dry seasons, while tropical disturbances within the trade winds can enhance summer rainfall.2
- Tropical Wet-Dry Climate (Aw): This climate is influenced by the seasonal migration of the tropical circulation. During the low-sun season, the ITCZ moves away, and the region is dominated by the periphery of the subtropical anticyclone, which is associated with the descending portion of the Hadley cell and the origin of the trade winds. This results in stable, subsiding air and a distinct dry season.345